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1

260 ps Molecular Dynamics Simulation of Substance P With Hydrated Dimyristoyl Phosphatidyl Choline Bilayer  

Microsoft Academic Search

We present here results on 260 pico seconds (ps) molecular dynamics (MD) simulation of substance P (SP) in hydrated bilayer of dimyristoyl phosphatidyl choline (DMPC) (39 molecules of DMPC with 776 water molecules). 260 ps MD simulation has been carried out in 0.001 ps time interval with united atom force field, using AMBER 4.0 package. Non bonded pair list was

V. Kothekar

1996-01-01

2

Modulation of histamine secretion from concanavalin A-activated rat mast cells by phosphatidyl serine, calcium, cAMP, pH and metabolic inhibitors  

Microsoft Academic Search

Concanavalin A (con A) on its own released about half the histamine of peritoneal mast cells from three strains of rats. Phosphatidyl serine (PS) potentiated the release to about 80%. The secretory process had a calcium-independent component of 15–20% at pH 7.5, which increased to a maximum of 40% at pH 6.5 and nearly disappeared at pH 8.0. It was

A. J. Shores; J. L. Mongar

1980-01-01

3

Autophagy is not universally required for phosphatidyl-serine exposure and apoptotic cell engulfment during neural development.  

PubMed

Apoptosis and autophagy are physiological processes implicated in the maintenance of cell and tissue homeostasis. We took advantage of the existence of multiple phases of developmental cell death in the embryonic chick retina and of the availability of short-term organotypic retinal cultures to explore the possible relationship between apoptosis and autophagy during neural development. We examined retinas at embryonic day 5, an early stage at which cell death is related to eye morphogenesis and to retinal ganglion cell generation, as well as at embryonic day 9, when cell death is associated with neurotrophic support of the retinal ganglion cells. Exposure to 3-methyl-adenine, a classical inhibitor of autophagy, elicited a selective accumulation of apoptotic bodies in the dorsotemporal area of embryonic day 5 retinas where neurogenesis is taking place. This accumulation was correlated with a blockage of phosphatidyl-serine presentation and, consequently, with a lack of engulfment of the dying cells by their neighbors. In striking contrast, none of these phenomena were observed in association with cell death in the optic nerve and optic fissure at embryonic day 5, or in embryonic day 9 retinas. Our data suggest that autophagy is essential for phosphatidyl-serine presentation by apoptotic cells during the phase of cell death associated to neurogenesis, but this is not a universal requirement for all phases of cell death occurring during retinal development. PMID:19587526

Mellén, María A; de la Rosa, Enrique J; Boya, Patricia

2009-10-18

4

The effects of subchronic d-serine on left-right discrimination learning, social interaction, and exploratory activity in APPswe/PS1 mice.  

PubMed

Glutamatergic neurotransmission is crucially involved in memory and cognition and severely affected patients with Alzheimer's disease. Modulation of NMDA receptors with agonists may reverse their late-stage symptoms. The effects of subchronic treatment of the NMDA receptor agonist, d-serine, were evaluated in APPswe/PS1 mutant mice harboring A? plaques in brain, regarding spatial discrimination learning, open-field activity, and social interaction in a three-chambered apparatus. d-serine (50mg/kg, i.p.) was superior to placebo in mutant mice during the reversal phase of left-right discrimination learning without affecting acquisition. The drug caused weaker effects in counteracting open-field hyperactivity and low social interaction with an unfamiliar stimulus mouse. These results indicate a favorable action of an NMDA receptor agonist on reversal learning in transgenic mice with amyloid pathology. PMID:23276661

Filali, Mohammed; Lalonde, Robert

2012-12-28

5

An economical assay for HDL phosphatidyl choline.  

PubMed

An economical enzymatic assay for HDL phosphatidyl choline is described, as adapted for the Cobas-Bio analyser (Hoffmann LaRoche). This method entails the enzymatic cleavage of phosphatidyl choline by phospholipase C from B. cereus, hydrolysis of phosphoryl choline and enzymatic determination of choline with choline oxidase by an enzymatic colour test. This method provides consistent values and is, by comparison to the enzymatic UV method (assaying choline with choline kinase in an optical test procedure), simpler to perform, more precise, and less expensive. PMID:6358403

Schriewer, H; Jung, G; Emke, F; Assmann, G

1983-10-01

6

HDL phosphatidyl choline and cigarette smoking.  

PubMed

The influence of cigarette smoking on the concentration of HDL phosphatidyl choline was tested in 1,546 male and 778 female employees in Westfalia, and the results were compared with the influence of cigarette smoking on the concentration of HDL cholesterol. Three subgroups were established for comparison: non-smokers = persons who had never smoked; ex-smokers = persons who had in the past been smokers but were now non-smokers; and smokers = persons who at present smoked cigarettes. Neither male nor female smokers proved to have different HDL phosphatidyl choline values when compared to non-smokers or ex-smokers, whereas male and female smokers were found to have decreased HDL cholesterol values when compared to non-smokers (p less than 0.01) or ex-smokers (p less than 0.05). In female smokers a correlation was found between HDL phosphatidyl choline values and the number of cigarettes smoked every day (r = -0.12, p less than 0.05). PMID:6482325

Assmann, G; Schulte, H; Schriewer, H

1984-01-01

7

Determination of HDL phosphatidyl choline by an enzymatic method.  

PubMed

A routine method is described for the enzymatic determination of phosphatidyl choline in the apolipoprotein B-free supernatant after precipitation of blood sera with phosphotungstic acid/MgCl2. The principle of this method is based on the specific cleavage of phosphatidyl choline by purified phospholipase C from B. cereus, and the enzymatic determination of choline by choline kinase after hydrolysis of phosphoryl-choline. The enzymatic method provides HDL phosphatidyl choline values which coincide with those of the conventional chemical method. Furthermore, the values obtained with the enzymatic method for the HDL fraction isolated by ultracentrifugation (1.063--1.21 kg/l) also closely coincide with those of the apolipoprotein B-free supernatant fraction. The precision, linearity and sample stability were also checked. The findings obtained show that the enzymatic assay introduced here is suitable for the routine determination of phosphatidyl choline in the apolipoprotein B-free supernatant. PMID:6854225

Schriewer, H; Jabs, H U; Günnewig, V; Assmann, G

1983-03-01

8

Peroxidation of polyunsaturated phosphatidyl-choline lipids during electroformation.  

PubMed

Giant unilamellar vesicles (GUVs) have been utilized both as model systems to study the physico-chemical properties of biomembranes and as host materials for investigating biological processes in microbioreactors. GUVs are commonly formed by an electroformation technique. However, there is a concern that the electric fields applied during electroformation can peroxidize lipid acyl chains, thereby altering the phospholipid composition and material properties of the synthesized vesicles. Here in this paper, we report the effect of electroformation on the extent of peroxidation of a number of polyunsaturated phosphatidyl-choline lipids (PULs). Specifically, we detected peroxidation byproducts (malonaldehydes and conjugated dienes) of the following lipids utilizing UV/Vis spectroscopy: dilinoleoyl phosphatidyl-choline (DLPC) (di-18:2 PC), dilinolenoyl phosphatidyl-choline (DNPC) (di-18:3 PC), diarachidonoyl phosphatidyl-choline (DAPC) (di-20:4 PC), and didocosaheexaenoyl phosphatidyl-choline (DHA) (di-22:6 PC). The results indicate that PC PULs lipids are prone to peroxidation, with increasing unsaturation levels leading to higher levels of peroxidation byproducts. The levels of peroxidation byproducts of DAPC were found to depend linearly on the strength of the electric field, indicating that the observed effects were due to the applied electric field. Lipid peroxidation can affect a number of important membrane properties, including domain formation and mechanical stability. Thus, alteration of the chemical composition of polyunsaturated lipids (PULs) by the electroformation technique can potentially complicate the interpretation of experimental studies that utilize GUVs composed of PULs. PMID:17107709

Zhou, Yong; Berry, Christina K; Storer, Patrick A; Raphael, Robert M

2006-11-14

9

Separation of fluorescent phosphatidyl inositol phosphates by CE.  

PubMed

Phosphatidyl inositol 4,5-bisphosphate (PIP2) and phosphatidyl inositol 3,4,5-trisphosphate (PIP3) labeled with 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-propionic acid (BODIPY FL) on the acyl chain or a phosphatidyl ethanolamine head group were separated by CE with LIF detection. Several methods and capillary-coating procedures were tested for the separation of these phosphatidyl inositol phosphates (PIPs) at 20 degrees C. Separation of the PIPs in less than 20 min with excellent resolution was achieved using a buffer containing sodium deoxycholate (SDC), 1-propanol, MgCl2 and the polymer coating reagent, EOTrol LR. The efficiency of the optimized method was as high as 1.3x10(5) plates. The dependence of the separation on the concentration of 1-propanol, SDC, and MgCl2 was determined. The separation of PIP2 and PIP3 was primarily due to differential binding of the lipids to Mg2+ rather than to different solubilities in the micellar phase. The role of the SDC was to prevent adsorption of the hydrophobic lipids to the capillary wall and thus enhance the efficiency. The fluorescent PIPs are of value for both in vitro and in vivo assays of phospholipid metabolism. In particular, the use of these lipids with the optimized capillary-based separation will be of utility for drug screening as well as cell-based assays. PMID:17366487

Mwongela, Simon M; Lee, Katherine; Sims, Christopher E; Allbritton, Nancy L

2007-04-01

10

Isolation and Characterization of Phosphatidyl Choline from Spinach Leaves.  

ERIC Educational Resources Information Center

|This inexpensive but informative experiment for undergraduate biochemistry students involves isolating phosphatidyl choline from spinach leaves. Emphasis is on introducing students to techniques of lipid extraction, separation of lipids, identification using thin layer chromatography, and identification of fatty acids. Three periods of three…

Devor, Kenneth A.

1979-01-01

11

Facile synthesis of phosphatidyl saccharides for preparation of anionic nanoliposomes with enhanced stability.  

PubMed

Physical stability during storage and against processing such as dehyration/rehydration are the cornerstone in designing delivery vehicles. In this work, mono-, di- and tri-saccharides were enzymatically conjugated to phosphatidyl group through a facile approach namely phospholipase D (PLD) mediated transphosphatidylation in a biphasic reaction system. The purified products were structurally identified and the connectivities of carbohydrate to phosphatidyl moiety precisely mapped by (1)H, (31)P, (13)C NMR pulse sequences and LC-ESI-FTMS. The synthetic phosphatidyl saccharides were employed as the sole biomimetic component for preparation of nanoliposomes. It was found that the critical micelle concentration (CMC) of phosphatidyl saccharides increases as more bulky sugar moiety (mono- to tri-) is introduced. Phosphatidyl di-saccharide had the largest membrane curvature. In comparison to the zwitterionic phosphatidylcholine liposome, all phosphatidyl saccharides liposomes are anionic and demonstrated significantly enhanced stability during storage. According to the confocal laser scan microscopy (CLSM) and atom force microscopy (AFM) analyses, the nanoliposomes formed by the synthetic phosphatidyl saccharides also show excellent stability against dehydration/rehydration process in which most of the liposomal structures remained intact. The abundance hydroxyl groups in the saccharide moieties might provide sufficient H-bondings for stabilization. This work demonstrated the synthesized phosphatidyl saccharides are capable of functioning as enzymatically liable materials which can form stable nanoliposomes without addition of stabilizing excipients. PMID:24069243

Song, Shuang; Cheong, Ling-Zhi; Falkeborg, Mia; Liu, Lei; Dong, Mingdong; Jensen, Henrik Max; Bertelsen, Kresten; Thorsen, Michael; Tan, Tianwei; Xu, Xuebing; Guo, Zheng

2013-09-12

12

Facile Synthesis of Phosphatidyl Saccharides for Preparation of Anionic Nanoliposomes with Enhanced Stability  

PubMed Central

Physical stability during storage and against processing such as dehyration/rehydration are the cornerstone in designing delivery vehicles. In this work, mono-, di- and tri-saccharides were enzymatically conjugated to phosphatidyl group through a facile approach namely phospholipase D (PLD) mediated transphosphatidylation in a biphasic reaction system. The purified products were structurally identified and the connectivities of carbohydrate to phosphatidyl moiety precisely mapped by 1H, 31P, 13C NMR pulse sequences and LC-ESI-FTMS. The synthetic phosphatidyl saccharides were employed as the sole biomimetic component for preparation of nanoliposomes. It was found that the critical micelle concentration (CMC) of phosphatidyl saccharides increases as more bulky sugar moiety (mono- to tri-) is introduced. Phosphatidyl di-saccharide had the largest membrane curvature. In comparison to the zwitterionic phosphatidylcholine liposome, all phosphatidyl saccharides liposomes are anionic and demonstrated significantly enhanced stability during storage. According to the confocal laser scan microscopy (CLSM) and atom force microscopy (AFM) analyses, the nanoliposomes formed by the synthetic phosphatidyl saccharides also show excellent stability against dehydration/rehydration process in which most of the liposomal structures remained intact. The abundance hydroxyl groups in the saccharide moieties might provide sufficient H-bondings for stabilization. This work demonstrated the synthesized phosphatidyl saccharides are capable of functioning as enzymatically liable materials which can form stable nanoliposomes without addition of stabilizing excipients.

Song, Shuang; Cheong, Ling-Zhi; Falkeborg, Mia; Liu, Lei; Dong, Mingdong; Jensen, Henrik Max; Bertelsen, Kresten; Thorsen, Michael; Tan, Tianwei; Xu, Xuebing; Guo, Zheng

2013-01-01

13

Acceptor Substrate Discrimination in Phosphatidyl-myo-inositol Mannoside Synthesis  

PubMed Central

Long term survival of the pathogen Mycobacterium tuberculosis in humans is linked to the immunomodulatory potential of its complex cell wall glycolipids, which include the phosphatidylinositol mannoside (PIM) series as well as the related lipomannan and lipoarabinomannan glycoconjugates. PIM biosynthesis is initiated by a set of cytosolic ?-mannosyltransferases, catalyzing glycosyl transfer from the activated saccharide donor GDP-?-d-mannopyranose to the acceptor phosphatidyl-myo-inositol (PI) in an ordered and regio-specific fashion. Herein, we report the crystal structure of mannosyltransferase Corynebacterium glutamicum PimB? in complex with nucleotide to a resolution of 2.0 ?. PimB? attaches mannosyl selectively to the 6-OH of the inositol moiety of PI. Two crystal forms and GDP- versus GDP-?-d-mannopyranose-bound complexes reveal flexibility of the nucleotide conformation as well as of the structural framework of the active site. Structural comparison, docking of the saccharide acceptor, and site-directed mutagenesis pin regio-selectivity to a conserved Asp residue in the N-terminal domain that forces presentation of the correct inositol hydroxyl to the saccharide donor.

Batt, Sarah M.; Jabeen, Talat; Mishra, Arun K.; Veerapen, Natacha; Krumbach, Karin; Eggeling, Lothar; Besra, Gurdyal S.; Futterer, Klaus

2010-01-01

14

HDL phosphatidyl choline and risk-factors of coronary heart disease.  

PubMed

As part of our epidemiological study of employees in Westphalia, the concentration of HDL phosphatidyl choline was measured in 1546 men and 778 women. The results were analysed in relation to the corresponding HDL cholesterol values, as well as the various risk factors for coronary heart disease. HDL phosphatidyl choline values were found to be age independent, higher in women than in men (p les than 0.001), and lognormally distributed in both sexes (men: mean 1.162 mmol/l, median 1.13 mmol/l, minimum 0.60 mmol/l, maximum 2.46 mmol/l; women: mean 1.370 mmol/l, median 1.34 mmol/l, minimum 0.55 mmol/l, maximum 2.46 mmol/l). A positive correlation (p less than 0.001) was found in both sexes between HDL phosphatidyl choline and HDL cholesterol (men: r = 0.588; women r = 0.605). A negative correlation was found in both sexes between HDL phosphatidyl choline values and body weight (men: r = -0.102 (p less than 0.001) women: r = -0.129 (p less than 0.001); and in men, but not in women, there was a negative correlation between HDL phosphatidyl choline values and triglycerides (men: r = -0.190 (p less than 0.001) women: r = -0.042). A negative correlation between HDL phosphatidyl choline and cigarette smoking was found only in female smokers (r = -0.121 (p less than 0.05). The correlation coefficients between HDL cholesterol and triglycerides as well as HDL cholesterol and relative body weight in both sexes were clearly higher than the corresponding correlation coefficient of HDL phosphatidyl choline. In men as well as in women the HDL phosphatidyl choline/HDL cholesterol ratio decreased with increasing HDL cholesterol values or decreasing triglyceride values in blood serum. PMID:6491614

Schriewer, H; Schulte, H; Assmann, G

1984-08-01

15

Relativistic Ps{sup -} and Ps  

SciTech Connect

Relativistic positronium (Ps) is of potential use to address fundamental questions in QED - e.g., through direct lifetime measurements of the 'para' state of Ps, severe magnetic quenching of the ortho-Ps lifetime, so-called 'superpenetration', and possibly to measure Ps-atom cross sections. Existing schemes for the production of relativistic positronium have relied on pion production through, e.g., nuclear interactions. This yields a low-intensity beam with relatively poor characteristics in both longitudinal and transverse emittance. By use of positrons impinging on a thin carbon foil inside a high-frequency rf cavity, it is proposed to generate relativistic positronium ions (Ps{sup -}) by rapid acceleration. Relativistic Ps can be derived from the positronium negative ion by subsequent Lorentz stripping or photodetachment. Intensities of the order 100 per second and Lorentz factors {approx_equal}20 are feasible with present technology.

Uggerhoej, U. I. [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)

2006-05-15

16

Effect of soy phosphatidyl choline on the bioavailability and nutritional health benefits of resveratrol  

Microsoft Academic Search

Resveratrol has several nutritional health benefits including a cardioprotective effect. Although it has high oral absorption, but its rapid metabolism results in less systemic availability and restrict its efficacy. To overcome this, resveratrol complex with hydrogenated soy phosphatidyl choline (HSPC) was developed and its effect was evaluated on doxorubicin induced cardiotoxicity in rats. The cardioprotective activity of the resveratrol complex

Kakali Mukherjee; M. Venkatesh; P. Venkatesh; B. P. Saha; Pulok K. Mukherjee

2011-01-01

17

Molecular Structure of Serine  

NSDL National Science Digital Library

Serine is required for the metabolism of fat, tissue growth, and a healthy immune system. It assists in the production of immunoglobulins and antibodies. Some of its derivatives such as ethanolamine are important components of the phospholipids found in biological membranes. Serine is found in meat and dairy products, wheat gluten, peanuts, and soy products. It is not clear how toxic this substance can be, although it is known that high levels of serine may cause immune suppression and psychological symptoms such as cerebral allergies.

2002-08-21

18

Antiphosphatidyl Serine Autoantibodies and Premature Coronary Events  

PubMed Central

Objectives: To determine whether antiphosphatidyl serine autoantibodies (aPS) are associated with increased risk of occurrence of coronary events in selected patients. Methods: This study compared 50 patients with coronary events with 30 controls, recruited from the cities of Mosul, Erbil, and Dohuk cities, Northern Iraq, between March 2004 and March 2005. The patient group consisted of 23 individuals with myocardial infarction and 27 with angina. We evaluated the presence of aPS antibodies (IgG and IgM isotypes) by an enzyme-linked immunosorbent assay. The studied cases were less than 50 years of age (mean ± SD, 39.6 ± 5.9) and had no recognizable risk factors. Results: The frequency of detecting IgG aPS was 10/50 (20%) among patients and 1/30 (3.3%) among controls, with significant difference and with adjusted odds ratio (OR) of 3.2 (95%CI, 1.1–9.1; p < 0.05). The IgM aPS frequency was 3/50 (6%) among patients and zero in the controls, with non-significant difference. The three cases were also IgG positive (i.e. the frequency rate for detection of aPS of IgM was the same as for IgG). Moreover, this marker (aPS) was detected in 8/12 (66.7%) of cases with unstable angina, in 2/15 (13.3%) with stable angina, and in none of the cases with myocardial infarction. Conclusion: IgG aPS autoantibodies are associated with increased risk of coronary events especially angina of unstable subset.

Ali, Hisham Y M; Abdullah, Zainalabideen A

2007-01-01

19

Phosphatidyl choline-based colloidal systems for dermal and transdermal drug delivery.  

PubMed

In this study we have prepared various phosphatidyl choline based colloidal systems, namely liposomes, transfersomes, microemulsions and micelles, using similar excipients and compared their ability to deliver drugs into and through the skin under occlusive and non-occlusive conditions. Hydrophilic propranolol hydrochloride (PHCl) and lipophilic propranolol base (PB) were used as model drugs. All tested parameters, that is formulation composition, drug characteristics and testing conditions, influenced skin permeability and skin retention. A trend was observed showing that the skin permeation as well as skin retention decreases with the amount of phosphatidyl choline in the formulations for both tested model drugs (micelles > transfersomes > liposomes > microemulsion). The lipophilic model drug had higher skin permeability especially when incorporated into the systems containing mainly hydrophilic excipients. Skin retention, however, was not affected by the drug hydrophilicity to the same extent as skin permeability. Occlusion increased both skin retention and skin permeation for both model drugs. PMID:19863162

Ferderber, Kristina; Hook, Sarah; Rades, Thomas

2009-01-01

20

Fluorescent products from reaction of peroxidizing polyunsaturated fatty acids with phosphatidyl ethanolamine and phenylalanine  

Microsoft Academic Search

Fluorescent chromophores produced by reaction of peroxidizing arachidonic acid or methyl docosahexaenoate with synthetic dipalmityl\\u000a phosphatidyl ethanolamine were lipid soluble, and those from reaction with phenylalanine were water soluble. In all reaction\\u000a systems that contained polyunsaturated fatty acid and only one amine compound, the development of fluorescence was linearly\\u000a related to oxygen absorption for 12–24 hr (p<0.001) and to the

C. J. Dillard; A. L. Tappel

1973-01-01

21

Measurement of phosphatidyl glycerol in amniotic fluid. Results in clinical practice.  

PubMed

A relatively rapid, unidimensional method of measuring phosphatidyl glycerol (PG) in amniotic fluid in order to assess pulmonary maturity was compared with measurement of the lecithin/sphingomyelin (L/S) ratio and the bubble test. Measurement of PG alone gave a higher predictive value (95%) than the L/S ratio while maintaining a low ratio rate of false-positive (2,3%) and false-negative results (3,1%). PMID:6701720

Patel, R D; Norman, R; Moodley, J; Sadhabris, A

1984-03-01

22

Physicochemical interpretation and prediction of the dimyristoyl phosphatidyl choline–water partition coefficient  

Microsoft Academic Search

The dimyristoyl phosphatidyl choline (DMPC)–water partition coefficient (logKDMPC–W) has been proposed as an alternative to the 1-octanol–water system (logKOW) for describing molecular hydrophobicity. In this study literature values of logKDMPC–W for 49 compounds were collated. Quantitative structure–activity relationships (QSARs) were developed for logKDMPC–W in an attempt to develop a predictive model for its estimation and to investigate its meaning. Despite

Hiren Patel; T. Wayne Schultz; Mark T. D Cronin

2002-01-01

23

pH dependent binding of chlorin-p6 with phosphatidyl choline liposomes  

NASA Astrophysics Data System (ADS)

The pH dependent binding of the photosensitizer chlorin-p6 with phosphatidyl choline liposomes was investigated at varying lipid:drug molar ratio. At pH 5.0, substantial changes in the absorption and emission spectra of the drug were observed when liposomes were added. At higher pH these changes became progressively smaller and observable only at higher liposomes concentrations. Studies carried out on fluorescence emission lifetimes as well as quenching of fluorescence with KI suggest that at pH 5.0 the drug localizes in the central region of lipid bilayer and for pH 6.0 and higher the drug binds closer to the liposome interface.

Das, K.; Jain, B.; Dube, A.; Gupta, P. K.

2005-01-01

24

Biosynthesis and localization of phosphatidyl-scyllo-inositol in barley aleurone cells.  

PubMed

A novel isomer of phosphatidylinositol (PI), phosphatidyl-scyllo-inositol, was characterized in the aleurone cells of barley seeds. In this investigation, the subcellular localization of scyllo-PI and the relative rates of biosynthesis and accumulation of [32P]phosphoric acid ([32Pi])-labeled scyllo- and myo-phosphoinositides in the plasma membrane and intracellular membrane pools were investigated. About 25% of the [32Pi]-labeled phospholipids were present in plasma membrane and 75% in intracellular membranes. Incorporation of [32Pi] into scyllo-PI was greater than into myo-PI in both the plasma membranes and intracellular membranes at all time points investigated, thus suggesting a higher rate of biosynthesis; however, the data do not preclude reduced breakdown of labeled scyllo-PI as a contributing factor. In vitro studies were conducted to investigate the presence of cytidinediphosphate diacylglycerol (CDP-DG):scyllo-inositol 3-phosphatidyltransferase (scyllo-PI synthase) and to optimize enzymatic activity. The inclusion of nonionic detergents (Brij 58 and Triton X-100) effected significant enhancement in the biosynthesis of scyllo-PI, whereas anionic, cationic, and zwitterionic detergents had little or no effect. This is the first evidence for CDP-DG:scyllo-inositol 3-phosphatidyltransferase activity. PMID:10188599

Carstensen, S; Pliska-Matyshak, G; Bhuvarahamurthy, N; Robbins, K M; Murthy, P P

1999-01-01

25

Peroxidative damage of the erythrocyte membrane in children with nephrotic syndrome  

Microsoft Academic Search

The structural composition of erythrocyte ghosts was analysed in children affected by steroid-responsive (SRNS) and unresponsive nephrotic syndrome (SUNS). No variation of either intrinsic or extrinsic ghost proteins was found by discontinuous SDS-electrophoresis associated with a very sensitive double staining technique. By contrast, the composition of inner-layer phospholipids — phosphatidyl ethanolamine (PE) and phosphatidyl serine (PS) — was altered in

Fabrizio Ginevri; Gian Marco Ghiggeri; Giovanni Candiano; Roberta Oleggini; Roberta Bertelli; Maria Teresa Piccardo; Francesco Perfumo; Rosanna Gusmano

1989-01-01

26

Interleukin-4-induced transcriptional activation by stat6 involves multiple serine/threonine kinase pathways and serine phosphorylation of stat6.  

PubMed

Stat6 transcription factor is a critical mediator of IL-4-specific gene responses. Tyrosine phosphorylation is required for nuclear localization and DNA binding of Stat6. The authors investigated whether Stat6-dependent transcriptional responses are regulated through IL-4-induced serine/threonine phosphorylation. In Ramos B cells, the serine/threonine kinase inhibitor H7 inhibited IL-4-induced expression of CD23. Treatment with H7 did not affect IL-4R-mediated immediate signaling events such as tyrosine phosphorylation of Jak1, Jak3, insulin receptor substrate (IRS)-1 and IRS-2, or tyrosine phosphorylation and DNA binding of Stat6. To analyze whether the H7-sensitive pathway was regulating Stat6-activated transcription, we used reporter constructs containing different IL-4 responsive elements. H7 abrogated Stat6-, as well as Stat5-, mediated reporter gene activation and partially reduced C/EBP-dependent reporter activity. By contrast, IL-4-induced transcription was not affected by wortmannin, an inhibitor of the phosphatidyl-inositol 3'-kinase pathway. Phospho-amino acid analysis and tryptic phosphopeptide maps revealed that IL-4 induced phosphorylation of Stat6 on serine and tyrosine residues in Ramos cells and in 32D cells lacking endogenous IRS proteins. However, H7 treatment did not inhibit the phosphorylation of Stat6. Instead, H7 inhibited the IL-4-induced phosphorylation of RNA polymerase II. These results indicate that Stat6-induced transcription is dependent on phosphorylation events mediated by H7-sensitive kinase(s) but that it also involves serine phosphorylation of Stat6 by an H7-insensitive kinase independent of the IRS pathway. (Blood. 2000;95:494-502) PMID:10627454

Pesu, M; Takaluoma, K; Aittomäki, S; Lagerstedt, A; Saksela, K; Kovanen, P E; Silvennoinen, O

2000-01-15

27

Formation of the serine octamer  

NASA Astrophysics Data System (ADS)

The mechanism of formation for clusters of serine generated by electrospray ionization is hypothesized to play a critical role in determining their ultimate properties. Under carefully manipulated electrospray source conditions, two distinct and well-separated distributions of clusters can be observed. The characteristics of the two cluster populations are consistent with different formation mechanisms, namely ion evaporation and charge residue. Upon further inspection, it is proposed that the magic number intensity, homochiral selectivity, and unique formation of the serine octamer are best explained within the context of the ion evaporation mechanism. As a consequence, solution phase properties of the octamer become important, particularly in relation to interface effects present on the surface of the charged droplet. In contrast, other clusters of serine, including the B form of the octamer, are probably generated by the charge residue mechanism and may have no connection to condensed phase phenomena.

Spencer, Emily A. C.; Ly, Tony; Julian, Ryan R.

2008-03-01

28

Evolutionary patterns of phosphorylated serines  

PubMed Central

Posttranslationally modified amino acids are chemically distinct types of amino acids and in terms of evolution they might behave differently from their non-modified counterparts. In order to check this possibility, we reconstructed the evolutionary history of phosphorylated serines in several groups of organisms. Comparisons of substitution vectors have revealed some significant differences in the evolution of modified and corresponding non-modified amino acids. In particular, phosphoserines are more frequently substituted to aspartate and glutamate, compared to non-phosphorylated serines. Reviewers This article was reviewed by Arcady Mushegian and Sandor Pongor.

2011-01-01

29

The hydrolysis of monolayers of phosphatidyl-[Me-14C]choline by phospholipase D  

PubMed Central

1. The hydrolysis of monolayers of phosphatidyl[Me-14C]choline at the air/water interface by phospholipase D (phosphatidylcholine phosphatidohydrolase) was investigated by a surface-radioactivity technique by using a flow counter. 2. Phosphatidylcholine of high specific radioactivity was prepared biosynthetically in good yield from [Me-14C]choline by using Saccharomyces cerevisiae. 3. At initial monolayer pressures between 12 and 25 dynes/cm. the hydrolysis occurred in two stages, an initial slow hydrolysis followed by a rapid hydrolysis. Below 3dynes/cm. and above 28dynes/cm. no enzymic hydrolysis of pure phosphatidylcholine monolayers could be detected. 4. The rapid hydrolysis was proportional to the enzyme concentration in the subphase, its pH optimum was 6·6, and 0·2mm-Ca2+ was required for maximal activity. 5. Hydrolysis of the film was accompanied by a pronounced fall in the surface pressure even though the phosphatidic acid formed did not leave the film. When the pressure fell to low values the hydrolysis ceased even if the film was only partially hydrolysed. 6. Above monolayer pressures of 28dynes/cm. enzymic hydrolysis could be initiated by inclusion of phosphatidic acid (and less effectively stearyl hydrogen sulphate) in the film, although the rates were not appreciably higher than those observed at 25dynes/cm. with a pure phosphatidylcholine film. 7. The initiation of the hydrolysis by phosphatidic acid was facilitated by the inclusion of high Ca2+ concentrations and certain carboxylic acid buffer anions in the subphase, although these did not activate by themselves. 8. The initiation of the hydrolysis at high pressures could not be related to any change in the surface potential brought about by the addition of the long-chain anions to the film, nor could it be ascribed to a surface dilution effect. 9. The results are discussed in relation to previous studies on the hydrolysis of phosphatidylcholine particles by the enzyme and also similar investigations on phosphatidylcholine monolayers with other phospholipases.

Quarles, R. H.; Dawson, R. M. C.

1969-01-01

30

The influence of silybin from Silybum marianum (L.) Gaertn. on in vitro phosphatidyl choline biosynthesis in rat livers.  

PubMed

In rat livers, removed 60 min after i.p. application of 150.6 mg/kg silybin-dihemisuccinate-di-Na-salt, in vitro incorporation of choline-(methyl-14C) into phosphatidyl choline by the postmitochondrial fraction of liver homogenates was enhanced in comparison with controls. These results are associated with increased activities of CTP-choline-phosphate cytidyltransferase. Enzyme activities were also enhanced after addition of 7.5 x 10(-6) mol/l silybin to incubation mixtures obtained from untreated rats. PMID:582978

Schriewer, H; Weinhold, F

1979-01-01

31

Type II Transmembrane Serine Proteases*  

PubMed Central

Analysis of genome and expressed sequence tag data bases at the turn of the millennium unveiled a new protease family named the type II transmembrane serine proteases (TTSPs) in a Journal of Biological Chemistry minireview (Hooper, J. D., Clements, J. A., Quigley, J. P., and Antalis, T. M. (2001) J. Biol. Chem. 276, 857–860). Since then, the number of known TTSPs has more than doubled, and more importantly, our understanding of the physiological functions of individual TTSPs and their contribution to human disease has greatly increased. Progress has also been made in identifying molecular substrates and endogenous inhibitors. This minireview summarizes the current knowledge of the rapidly advancing TTSP field.

Bugge, Thomas H.; Antalis, Toni M.; Wu, Qingyu

2009-01-01

32

l-Serine Deaminase of Escherichia coli  

PubMed Central

The native l-serine deaminase (l-serine hydrolyase, deaminating, EC 4.2.1.13) of Escherichia coli K-12, which seems to be a very labile protein, is rather stable in concentrated solution. Dilution rapidly inactivates it, but in the presence of a saturating concentration of l-serine the molecule is protected from inactivation. It is a very specific enzyme; l-serine is the sole substrate with a Km value of 6.60 × 10?3m. d-Serine and l-cysteine are competitive inhibitors. Substrate saturation curves of the native enzyme show sigmoid shape, whereas the enzyme liberated from the bacteria in the presence of l-serine exhibits normal Michaelis-Menten kinetics.

Alfoldi, Lajos; Rasko, Istvan; Kerekes, Erzsebet

1968-01-01

33

Implementing PS-Merge Operator  

NASA Astrophysics Data System (ADS)

When information comes from different sources inconsistent beliefs may appear. To handle inconsistency, several model-based belief merging operators have been proposed. Starting from the beliefs of a group of agents which might conflict, these operators return a unique consistent belief base which represents the beliefs of the group. The operators, parameterized by a distance between interpretations and aggregation function, usually only take into account consistent bases. Consequently, the information in the base, which is not responsible for conflicts, may be ignored. This paper presents an algorithm for implementing the PS-Merge operator, an alternative method of merging that uses the notion of Partial Satisfiability instead of distance measures. This operator allows us to take into account inconsistent bases. Also in order to use the PS-Merge operator to solve ITC problems a pre-processing transformation was proposed.

Macías, Verónica Borja; Parra, Pilar Pozos

34

Arachidonic acid activates Kir2.3 channels by enhancing channel-phosphatidyl-inositol 4,5-bisphosphate interactions.  

PubMed

Kir2.0 channels play a significant role in setting the resting membrane potential, modulating action potential wave form, and buffering extracellular potassium. One member of this family, Kir2.3, is highly expressed in the heart and brain and is modulated by a variety of factors, including arachidonic acid (AA). Using two-electrode voltage clamp and inside-out patch clamp recordings from Xenopus laevis oocytes expressing Kir2.3 channels, we found that AA selectively activated Kir2.3 channels with an EC(50) of 0.59 muM and that this activation required phosphatidyl inositol 4,5-bisphosphate (PIP(2)). We found that AA activated Kir2.3 by enhancing channel-PIP(2) interactions as demonstrated by a shift in PIP(2) activation curve. EC(50) for channel activation by PIP(2) were 36 and 12 muM in the absence and presence of AA, respectively. A single point mutation on the channel C terminus that enhanced basal channel-PIP(2) interactions reduced the sensitivity of the channel to AA. Effects of AA are mediated through cytoplasmic sites on the channel by increasing the open probability, mainly due to more frequent bursts of opening in the presence of PIP(2). Therefore, enhanced interaction with PIP(2) is the molecular mechanism for Kir2.3 channel activation by AA. PMID:18202303

Wang, Chuan; Mirshahi, Uyenlinh L; Liu, Boyi; Jia, Zhanfeng; Mirshahi, Tooraj; Zhang, Hailin

2008-01-17

35

Liver-targeted antiviral nucleosides: Enhanced antiviral activity of phosphatidyl-dideoxyguanosine versus dideoxyguanosine in woodchuck hepatitis virus infection in vivo  

Microsoft Academic Search

It would be desirable to develop antiviral agents that can be targeted to liver to enhance their antiviral effects and reduce nonhepatic toxicity. 2',3'-Dideoxyguanosine (ddG) has been found to be a potent and selective antihepatitis B agent both in vitro and in vivo. To evaluate ddG and its liver-targeted analog, we synthesized a series of phosphatidyl-ddGs and incubated them with

BA Korba; H Xie; KN Wright; WE Hornbuckle; JL Gerin; BC Tennant; KY Hostetler

1996-01-01

36

I papers and notes on methodology Synthesis of polar head group homologs of all-trans-cyclopentano-phosphatidylcholine, phosphatidyl-N,N-dimethylethanolamine, and phosphatidylethanolamine132  

Microsoft Academic Search

The polar head group region of a conformationally restricted analog of phosphatidic acid (diacylglycero-phosphate) has been systematically modified to give analogs of phosphati- dylcholine, phosphatidylethanolamine, and phosphatidyl-N,N- dimethylethanolamine. These analogs differ from their natural counterpart in both the backbone region and in the polar head region, respectively, as follows: the diacylglyceryl moiety has been replaced by an all-trans diacylcyclopentane-l,2,3-triol moiety

Hassan Pajouhesh; Anthony J. Hancock

37

Role of p53 Serine 46 in p53 Target Gene Regulation  

PubMed Central

The tumor suppressor p53 plays a crucial role in cellular growth control inducing a plethora of different response pathways. The molecular mechanisms that discriminate between the distinct p53-responses have remained largely elusive. Here, we have analyzed the p53-regulated pathways induced by Actinomycin D and Etoposide treatment resulting in more growth arrested versus apoptotic cells respectively. We found that the genome-wide p53 DNA-binding patterns are almost identical upon both treatments notwithstanding transcriptional differences that we observed in global transcriptome analysis. To assess the role of post-translational modifications in target gene choice and activation we investigated the genome-wide level of phosphorylation of Serine 46 of p53 bound to DNA (p53-pS46) and of Serine 15 (p53-pS15). Interestingly, the extent of S46 phosphorylation of p53 bound to DNA is considerably higher in cells directed towards apoptosis while the degree of phosphorylation at S15 remains highly similar. Moreover, our data suggest that following different chemotherapeutical treatments, the amount of chromatin-associated p53 phosphorylated at S46 but not at pS15 is higher on certain apoptosis related target genes. Our data provide evidence that cell fate decisions are not made primarily on the level of general p53 DNA-binding and that post-translationally modified p53 can have distinct DNA-binding characteristics.

Smeenk, Leonie; van Heeringen, Simon J.; Koeppel, Max; Gilbert, Bianca; Janssen-Megens, Eva; Stunnenberg, Hendrik G.; Lohrum, Marion

2011-01-01

38

Early Evolution of Metazoan Serine\\/Threonine and Tyrosine Kinases: Identification of Selected Kinases in Marine Sponges  

Microsoft Academic Search

The phylum Porifera (sponges) was the first to diverge from the common ancestor of the Metazoa. In this study, six cDNAs coding for protein-serine\\/threonine kinases (PS\\/TKs) are presented; they have been isolated from libraries obtained from the demosponges Geodia cydonium and Suberites domuncula and from the calcareous sponge Sycon ruphanus. Sequence alignments of the catalytic domains revealed that two major

Isabel M. Miiller; Werner E. G. Miiller

39

Polarizabilities of the Ps negative ion  

SciTech Connect

We have calculated polarizabilities ({alpha}{sub 1}, {beta}{sub 1}, {gamma}{sub 1}, {alpha}{sub 2}, {beta}{sub 2}, and {gamma}{sub 2}) of Ps{sup -} by the pseudostate method. These parameters can be used to calculate Rydberg states of Ps{sup -} in the presence of an external electron with high quantum numbers N and L. They are also of importance in a system containing Ps{sup -} bound to a proton [PsH] and also Rydberg states of Ps{sub 2}.

Bhatia, A. K.; Drachman, Richard J. [Heliophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)

2007-06-15

40

o-Ps cooling for antihydrogen production  

NASA Astrophysics Data System (ADS)

AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) experiment in progress at CERN has planned to produce antihydrogen (bar H) by using the resonant charge exchange process between orthopositronium (o-Ps) and antiproton (bar p). Its primary goal is the realization of a cold bar H beam for the first measurement of the Earth's gravitational acceleration on antimatter. A demanding condition for large o-Ps - bar p cross section is the cooling of o-Ps at temperatures lower than at least 160 K. We will present recent results of o-Ps formation and cooling at cryogenic temperatures in a novel silicon positron/Ps converter in which oxidized nano-channels perpendicular to the surface were produced. The possibility to tune the nano-channels dimension to optimize o-Ps kinetic energy emission and to avoid o-Ps quantum confinement is discussed.

Mariazzi, S.; Brusa, R. S.

2011-01-01

41

D-serine increases adult hippocampal neurogenesis.  

PubMed

Adult hippocampal neurogenesis results in the continuous formation of new neurons and is a process of brain plasticity involved in learning and memory. The neurogenic niche regulates the stem cell proliferation and the differentiation and survival of new neurons and a major contributor to the neurogenic niche are astrocytes. Among the molecules secreted by astrocytes, D-serine is an important gliotransmitter and is a co-agonist of the glutamate, N-methyl-D-aspartate (NMDA) receptor. D-serine has been shown to enhance the proliferation of neural stem cells in vitro, but its effect on adult neurogenesis in vivo is unknown. Here, we tested the effect of exogenous administration of D-serine on adult neurogenesis in the mouse dentate gyrus. We found that 1 week of treatment with D-serine increased cell proliferation in vivo and in vitro and increased the density of neural stem cells and transit amplifying progenitors. Furthermore, D-serine increased the survival of newborn neurons. Together, these results indicate that D-serine treatment resulted in the improvement of several steps of adult neurogenesis in vivo. PMID:24009551

Sultan, Sebastien; Gebara, Elias G; Moullec, Kristell; Toni, Nicolas

2013-08-29

42

Cloning, sequencing, and overexpression in Escherichia coli of a phenylserine dehydratase gene from Ralstonia pickettii PS22.  

PubMed

The structural gene coding for phenylserine dehydratase from Ralstonia pickettii PS22 was cloned into Escherichia coli cells, and the nucleotide sequence was identified. The predicted amino acid sequence had high sequence similarity to biodegradative and biosynthetic threonine dehydratases from E. coli and serine dehydratase from human liver. Transformed E. coli cells overproduced phenylserine dehydratase, and the recombinant enzyme was purified to homogeneity with a high yield and characterized. PMID:12596884

Okuda, Heiwa; Nagata, Shinji; Misono, Haruo

2002-12-01

43

Serine Hydroxymethyltransferase from Soybean Root Nodules 1  

PubMed Central

Serine hydroxymethyltransferase has been purified 1,550-fold from the plant fraction of soybean (Glycine max [L]. Merr. cv Williams) nodules. The pH optimum for the enzyme was at 8.5. The native molecular weight was 230,000 with a subunit molecular weight of 55,000 which suggested a tetramer of identical subunits. The enzyme kinetics for the enzyme were Michaelis-Menten; there was no evidence for cooperativity in the binding of either substrates or product inhibitors. There were two Km values for serine at 1.5 and 40 millimolar. The Km for l-tetrahydrofolate was 0.25 millimolar. l-Methyl-, l-methenyl-, and l-methylene-tetrahydrofolates were all noncompetitive inhibitors with l-tetrahydrofolate with Ki values of 1.8, 3.0, and 2.9 millimolar, respectively. Glycine was a competitive inhibitor with serine with a Ki value of 3.0 millimolar. The intersecting nature of the double reciprocal plots together with the product inhibition data suggested an ordered mechanism with serine the first substrate to bind and glycine the last product released. The enzyme was insensitive to a wide range of metabolites which have previously been reported to affect its activity. These results are discussed with respect to the roles of serine hydroxymethyltransferase and the one-carbon metabolite pool in control of the carbon flow to the purine biosynthetic pathway in ureide biogenesis.

Mitchell, Michelle K.; Reynolds, Paul H. S.; Blevins, Dale G.

1986-01-01

44

Sorafenib/Regorafenib and phosphatidyl inositol 3 kinase/thymoma viral proto-oncogene inhibition interact to kill tumor cells.  

PubMed

The present studies were undertaken to determine whether the multikinase inhibitors sorafenib/regorafenib cooperated with clinically relevant , phosphatidyl inositol 3 kinase (PI3K)-thymoma viral proto-oncogene (AKT) inhibitors to kill tumor cells. In liver, colorectal, lung, breast, kidney, and brain cancer cells, at clinically achievable doses, sorafenib/regorafenib and the PI3K inhibitor acetic acid (1S,4E,10R,11R,13S,14R)-[4-diallylaminomethylene-6-hydroxy-1-methoxymethyl-10,13-dimethyl-3,7,17-trioxo-1,3,4,7,10,11,12,13,14,15,16,17-dodecahydro-2-oxa-cyclopenta[a]phenanthren-11-yl ester (PX-866) cooperated in a greater than additive fashion to kill tumor cells. Cells lacking phosphatase and tensin homolog were as sensitive to the drug combination as cells expressing the protein. Similar data were obtained using the AKT inhibitors perifosine and 8-[4-(1-aminocyclobutyl)phenyl]-9-phenyl-1,2,4-triazolo[3,4-f] [1,6]naphthyridin-3(2H)-one hydrochloride (MK2206). PX-866 treatment abolished AKT/glycogen synthase kinase 3 (GSK3) phosphorylation, and cell killing correlated with reduced activity of AKT and mammalian target of rapamycin (mTOR). Expression of activated AKT and to a lesser extent activated mTOR reduced drug combination lethality. Expression of B-cell lymphoma-extra large or dominant negative caspase 9, but not cellular FLICE (FADD-like IL-1b-converting enzyme)-inhibitory protein short, protected cells from the drug combination. Treatment of cells with PX-866 increased protein levels of p62, lysosome-associated membrane protein 2 (LAMP2), and microtubule-associated protein light chain (LC) 3 and LC3II that correlated with a large increase in LC3-green fluorescent protein (GFP) vesicle numbers. Exposure of PX-866 treated cells to sorafenib reduced p62 and LAMP2 levels, decreased the ratio of LC3 to LC3II, and reduced LC3-GFP vesicle levels. Knockdown of Beclin1 or autophagy-related 5 suppressed drug toxicity by ?40%. In vivo, sorafenib and PX-866 or regorafenib and MK2206 cooperated to suppress the growth of established HuH7 and HCT116 tumors, respectively. Collectively our data demonstrate that the combination of sorafenib family kinase inhibitors with inhibitors of the PI3K/AKT pathway kills tumor cells in vitro and in vivo. PMID:23877009

Sajithlal, Gangadharan B; Hamed, Hossein A; Cruickshanks, Nichola; Booth, Laurence; Tavallai, Seyedmehrad; Syed, Jahangir; Grant, Steven; Poklepovic, Andrew; Dent, Paul

2013-07-22

45

Serine protease inhibitors of parasitic helminths.  

PubMed

Serine protease inhibitors (serpins) are a superfamily of structurally conserved proteins that inhibit serine proteases and play key physiological roles in numerous biological systems such as blood coagulation, complement activation and inflammation. A number of serpins have now been identified in parasitic helminths with putative involvement in immune regulation and in parasite survival through interference with the host immune response. This review describes the serpins and smapins (small serine protease inhibitors) that have been identified in Ascaris spp., Brugia malayi, Ancylostoma caninum Onchocerca volvulus, Haemonchus contortus, Trichinella spiralis, Trichostrongylus vitrinus, Anisakis simplex, Trichuris suis, Schistosoma spp., Clonorchis sinensis, Paragonimus westermani and Echinococcus spp. and discusses their possible biological functions, including roles in host-parasite interplay and their evolutionary relationships. PMID:22310379

Molehin, Adebayo J; Gobert, Geoffrey N; McManus, Donald P

2012-02-06

46

L-serine dehydratase from Arthrobacter globiformis.  

PubMed Central

1. L-Serine dehydratase (EC 4.2.1.13) was purified 970-fold from glycine-grown Arthrobacter globiformis to a final specific activity of 660micronmol of pyruvate formed/min per mg of protein. 2. The enzyme is specific for L-serine; D-serine, L-threonine and L-cysteine are not attacked. 3. The time-course of pyruvate formation by the purified enzyme, in common with enzyme in crude extracts and throughout the purification, is non-linear. The reaction rate increases progressively for several minutes before becoming constant. The enzyme is activated by preincubation with L-serine and a linear time-course is then obtained. 4. The substrate-saturation curve for L-serine is sigmoid. The value of [S]0.5 varies with protein concentration, from 6.5mM at 23microng/ml to 20mM at 0.23microng/ml. The Hill coefficient remains constant at 2.9.5 The enzyme shows a non-specific requirement for a univalent or bivalent cation. Half-maximal activity is produced by 1.0mM-MgCl2 or by 22.5mM-KCl. 6. L-Cysteine and D-serine act as competitive inhibitors of L-serine dehydratase, with Ki values of 1.2 and 4.9mM respectively. L-Cysteine, at higher concentrations, also causes a slowly developing irreversible inhibition of the enzyme. 7. Inhibition by HgCl2 (5micronM)can be partially reversed in its initial phase by 1mM-L-cysteine, but after 10 min it becomes irreversible. 8. In contrast with the situation in all cell-free preparations, toluene-treated cells of A. globiformis form pyruvate from L-serine at a constant rate from the initiation of the reaction, show a hyperbolic substrate-saturation curve with an apparent Km of 7mM and do not require a cation for activity.

Gannon, F; Bridgeland, E S; Jones, K M

1977-01-01

47

Nitric oxide S-nitrosylates serine racemase, mediating feedback inhibition of d-serine formation  

PubMed Central

Serine racemase (SR) generates d-serine, a coagonist with glutamate at NMDA receptors. We show that SR is physiologically S-nitrosylated leading to marked inhibition of enzyme activity. Inhibition involves interactions with the cofactor ATP reflecting juxtaposition of the ATP-binding site and cysteine-113 (C113), the site for physiological S-nitrosylation. NMDA receptor physiologically enhances SR S-nitrosylation by activating neuronal nitric-oxide synthase (nNOS). These findings support a model whereby postsynaptic stimulation of nitric-oxide (NO) formation feeds back to presynaptic cells to S-nitrosylate SR and decrease d-serine availability to postsynaptic NMDA receptors.

Mustafa, Asif K.; Kumar, Manish; Selvakumar, Balakrishnan; Ho, Gary P. H.; Ehmsen, Jeffrey T.; Barrow, Roxanne K.; Amzel, L. Mario; Snyder, Solomon H.

2007-01-01

48

Revealing the multiple structures of serine  

PubMed Central

We explored the conformational landscape of the proteinogenic amino acid serine [CH2OHCH(NH2)COOH] in the gas phase. Solid serine was vaporized by laser ablation, expanded in a supersonic jet, and characterized by Fourier transform microwave spectroscopy. In the isolation conditions of the jet there have been discovered up to seven different neutral (non-zwitterionic) structures of serine, which are conclusively identified by the comparison between the experimental values of the rotational and quadrupole coupling constants with those predicted by ab initio calculations. These seven forms can serve as a basis to represent the shape of serine in the gas phase. From the postexpansion abundances we derived the conformational stability trend, which is controlled by the subtle network of intramolecular hydrogen bonds formed between the polar groups in the amino acid backbone and the hydroxy side chain. It is proposed that conformational cooling perturbs the equilibrium conformational distribution; thus, some of the lower-energy forms are “missing” in the supersonic expansion.

Blanco, Susana; Sanz, M. Eugenia; Lopez, Juan C.; Alonso, Jose L.

2007-01-01

49

Resurgence of Serine: An Often Neglected but Indispensable Amino Acid*  

PubMed Central

Serine is generally classified as a nutritionally nonessential (dispensable) amino acid, but metabolically, serine is indispensible and plays an essential role in several cellular processes. Serine is the major source of one-carbon units for methylation reactions that occur via the generation of S-adenosylmethionine. The regulation of serine metabolism in mammalian tissues is thus of critical importance for the control of methyl group transfer. In addition to the well known role of d-serine in the brain, l-serine has recently been implicated in breast cancer and other tumors due in part to the genomic copy number gain for 3-phosphoglycerate dehydrogenase, the enzyme that controls the entry of glycolytic intermediates into the pathway of serine synthesis. Here, we review recent information regarding the synthesis of serine and the regulation of its metabolism and discuss the role played by phosphoenolpyruvate carboxykinase in this process.

Kalhan, Satish C.; Hanson, Richard W.

2012-01-01

50

Characterization and localization of a human serine racemase  

Microsoft Academic Search

d-serine is present in the mammalian central nervous system, where it acts as one of the co-activators of N-methyl-D aspartate receptors. Synthesis of d-serine is catalyzed by the serine racemase enzyme. The current studies report on the isolation of a cDNA encoding a human serine racemase (SRR) from the human neuronal like cell line, NT2N. The SRR gene was localized

Menghang Xia; Yuan Liu; David J. Figueroa; Chi-Sung Chiu; Nan Wei; Ann-Marie Lawlor; Ping Lu; Cyrille Sur; Ken S. Koblan; Thomas M. Connolly

2004-01-01

51

Human serine racemase: moleular cloning, genomic organization and functional analysis  

Microsoft Academic Search

High levels of d-serine are found in mammalian brain, where it is an endogenous agonist of the strichinine-insensitive site of N-methyl d-aspartate type of glutamate receptors. d-serine is enriched in protoplasmic astrocytes that occur in gray matter areas of the brain and was shown to be synthesized from l-serine . We now report cloning and expression of human serine racemase,

Joari De Miranda; Ana Santoro; Simone Engelender; Herman Wolosker

2000-01-01

52

In vivo D-serine hetero-exchange through alanine-serine-cysteine (ASC) transporters detected by microelectrode biosensors.  

PubMed

D-serine, a co-agonist of N-methyl D-aspartate (NMDA) receptors, has been implicated in neurological and psychiatric disorders such as cerebral ischemia, lateral amyotrophic sclerosis, or schizophrenia. D-serine signaling represents an important pharmacological target for treating these diseases; however, the biochemical mechanisms controlling extracellular D-serine levels in vivo are still unclear. D-serine heteroexchange through small neutral amino acid transporters has been shown in cell cultures and brain slices and could provide a biochemical mechanism for the control of D-serine extracellular concentration in vivo. Alternatively, exocytotic D-serine release has also been proposed. In this study, the dynamics of D-serine release and clearance were explored in vivo on a second-by-second time scale using microelectrode biosensors. The rate of D-serine clearance in the rat frontal cortex after a microionophoretic injection revealed a transporter-mediated uptake mechanism. D-serine uptake was blocked by small neutral l-amino acids, implicating alanine-serine-cysteine (ASC) transporters, in particular high affinity Asc-1 and low affinity ASCT2 transporters. Interestingly, changes in alanine, serine, or threonine levels resulted in D-serine release through ASC transporters. Asc-1, but not ASCT2, appeared to release D-serine in response to changes in amino acid concentrations. Finally, neuronal silencing by tetrodotoxin increased D-serine extracellular concentration by an ASC-transporter-dependent mechanism. Together, these results indicate that D-serine heteroexchange through ASC transporters is present in vivo and may constitute a key component in the regulation of D-serine extracellular concentration. PMID:23581544

Maucler, Caroline; Pernot, Pierre; Vasylieva, Natalia; Pollegioni, Loredano; Marinesco, Stéphane

2013-04-12

53

(PS)2: protein structure prediction server.  

PubMed

Protein structure prediction provides valuable insights into function, and comparative modeling is one of the most reliable methods to predict 3D structures directly from amino acid sequences. However, critical problems arise during the selection of the correct templates and the alignment of query sequences therewith. We have developed an automatic protein structure prediction server, (PS)2, which uses an effective consensus strategy both in template selection, which combines PSI-BLAST and IMPALA, and target-template alignment integrating PSI-BLAST, IMPALA and T-Coffee. (PS)2 was evaluated for 47 comparative modeling targets in CASP6 (Critical Assessment of Techniques for Protein Structure Prediction). For the benchmark dataset, the predictive performance of (PS)2, based on the mean GTD_TS score, was superior to 10 other automatic servers. Our method is based solely on the consensus sequence and thus is considerably faster than other methods that rely on the additional structural consensus of templates. Our results show that (PS)2, coupled with suitable consensus strategies and a new similarity score, can significantly improve structure prediction. Our approach should be useful in structure prediction and modeling. The (PS)2 is available through the website at http://ps2.life.nctu.edu.tw/. PMID:16844981

Chen, Chih-Chieh; Hwang, Jenn-Kang; Yang, Jinn-Moon

2006-07-01

54

Hepatocyte growth factor is a preferred in vitro substrate for human hepsin, a membrane-anchored serine protease implicated in prostate and ovarian cancers  

Microsoft Academic Search

Hepsin is a membrane-anchored, trypsin-like serine protease with prominent expression in the human liver and tumours of the prostate and ovaries. To better understand the biological functions of hepsin, we identified macromolecular substrates employing a tetrapeptide PS-SCL (positional scanning-synthetic combinator- ial library) screen that rapidly determines the P1-P4 substrate specificity. Hepsin exhibited strong preference at the P1 position forarginineoverlysine,andfavouredthreonine,leucineoraspara- gineattheP2,glutamineorlysineattheP3,andprolineorlysineat

Sylvia Herter; Wade Aaron; Timothy Gabriele; Gene Cutler; Ping Cao; Youngchool Choe; Nigel Walker; David Meininger; Timothy Hoey

2005-01-01

55

Serine proteases, serine protease inhibitors, and protease-activated receptors: roles in synaptic function and behavior  

PubMed Central

Serine proteases, serine protease inhibitors, and protease-activated receptors have been intensively investigated in the periphery and their roles in a wide range of processes—coagulation, inflammation, and digestion, for example—have been well characterized (see Coughlin, 2000; Macfarlane et al., 2001; Molinari et al., 2003; Wang et al., 2008; Di Cera, 2009 for reviews). A growing number of studies demonstrate that these protein systems are widely expressed in many cell types and regions in mammalian brains. Accumulating lines of evidence suggest that the brain has co-opted the activities of these interesting proteins to regulate various processes underlying synaptic activity and behavior. In this review, we discuss emerging roles for serine proteases in the regulation of mechanisms underlying synaptic plasticity and memory formation.

Almonte, Antoine G.; Sweatt, J. David

2011-01-01

56

Final results for ?± production in the HARP/PS214 experiment at CERN PS  

NASA Astrophysics Data System (ADS)

The final results on ?± production in proton nucleus or ?± nucleus interactions for incident particle momenta between 1.5 GeV/c and 15 GeV/c as measured in the HARP/PS214 experiment at CERN PS are presented.

HARP/PS214 Collaboration; Bonesini, M.

2012-08-01

57

Classification between PS and Stego Images Based on Noise Model  

Microsoft Academic Search

Owing to the popular usage of Photoshop, PS images which are processed by Photoshop or other similar software nowadays emerge increasingly. PS images may be misfortunes to steganalysis. The similarities and differences between PS and stego images are analyzed in this paper, and a method is proposed to classify the natural, PS and stego images. The first-scale diagonal subband obtained

Xiongfei He; Fenlin Liu; Xiangyang Luo; Chunfang Yang

2009-01-01

58

The Binding Energy of PsH  

NASA Astrophysics Data System (ADS)

In response to proposed measurements of Ps scattering by the St. Olaf's positron experimental group [1], we have begun a theoretical investigation of Ps scattering from simple atoms. For our first step of this investigation, we have computed the binding energy of the fundamental four-body Coulomb system, PsH. We have used a very flexible trial function of Hylleraas form which includes all inter-particle distances. Our most accurate value of the binding energy compares favorably with a previous calculation that also used Hylleraas functions [2] and with the most accurate calculation to-date which used explicitly correlated Gaussians [3]. [4pt] [1] Jason Engbrecht, Private communication, (2008).[0pt] [2] Zong-Chao Yan and Y. K. Ho, Phys. Rev. A 59, 2697 (1999).[0pt] [3] Sergiy Bubin and Ludwik Adamowicz, Phys. Rev. A 74, 052502 (2006).

Woods, D.; Ward, S. J.; van Reeth, P.

2010-03-01

59

d-Serine diffusion through the blood-brain barrier: effect on d-serine compartmentalization and storage.  

PubMed

d-Serine is a co-agonist of N-methyl-d-aspartate (NMDA) receptors. It has been implicated in the etiology of schizophrenia and has shown efficacy as an adjuvant to reduce positive and negative symptoms of schizophrenia. In addition, d-serine can modulate cognition in animals when administered alone. However, the neurochemical effects of exogenous d-serine on extra- and intra-cellular d-serine brain levels are poorly understood. In this study, we used both high performance liquid chromatography (HPLC) and enzyme-based microelectrode biosensors to quantify d-serine in the rat brain. We demonstrated levels of 2.3-2.8?M in the extracellular medium, 4?M in plasma and 188pmol/mg in brain tissue samples. An intraperitoneal (i.p.) d-serine injection (1g/kg) produced a slow increase in extracellular d-serine concentration in the cortex despite a surge in d-serine up to 13mM in the plasma, indicating poor diffusion through the blood-brain barrier. Using the respective volume fractions of blood, extracellular and intracellular spaces published in the literature, we estimated that d-serine intracellular stores represented more than 99% of total d-serine. These intracellular stores almost doubled 3h after d-serine administration. Overall, our data indicate that d-serine administration increases brain extra- and intra-cellular concentrations despite weak diffusion through the blood-brain barrier. These results pave the way for a better understanding of the neurochemical mechanisms by which d-serine administration modulates cognition. PMID:22465696

Pernot, Pierre; Maucler, Caroline; Tholance, Yannick; Vasylieva, Natalia; Debilly, Gabriel; Pollegioni, Loredano; Cespuglio, Raymond; Marinesco, Stéphane

2012-03-23

60

Accelerators for the PS neutrino beam  

NASA Astrophysics Data System (ADS)

A recent memorandum for an experimental proposal [1] was discussed during the CERN PS and SPS experimental committee (SPSC) of April 2011 and at the Research Board of June 2011. The proposed experiment, with objective to investigate the anomalous ?? ? ?e oscillations, aims at re-using the discontinued CERN PS Neutrino Facility (PSNF) and experimental zones to install a 150 ton liquid argon time projection chamber (LArTPC) as near detector and a 600 ton LArTPC as far detector. This article will summarize the experimental needs, the proposed facility layout, a primary beam production scheme and the requirements for the reconstruction of the PSNF.

Steerenberg, R.; Calviani, M.; Gschwendtner, E.; Pardons, A.; Vincke, H.

2013-02-01

61

Characterization of a serine hydroxymethyltransferase for L-serine enzymatic production from Pseudomonas plecoglossicida.  

PubMed

Pseudomonas plecoglossicida, a bacterium strain that exhibits high Serine hydroxymethyltransferase (SHMT) activity, was isolated from the seawater. A full-length glyA encoding SHMT was obtained by a modified thermal asymmetric interlaced-PCR (TRIL-PCR), which consisted of 1,254 bp, encoded a 417 amino acid polypeptide, and shared the highest identity (75 %) with a glyA gene from Acinetobacter radioresistens CMC-1. Recombinant glyA gene was expressed in Escherichia coli BL21 (DE3) and purified by electrophoretic homogeneity. The enzyme showed the optimal activity at pH 8.0 and 40 °C, and remained stable in high alkali conditions. Using SHMT to produce L-serine by catalyzing the reaction of glycine and tetrahydrofolate is one of the most promising routes to synthesize L-serine, achieving 33.4 mM L-serine at the 12th h of the enzymatic reaction with the substrates of glycine (133 mM) and formaldehyde (13.3 mM). The properties make the SHMT a candidate for further enzymatic studies and industrial applications. PMID:23913024

Jiang, Wei; Xia, Bingzhao; Huang, Junjie; Liu, Ziduo

2013-08-03

62

Serine incorporation into the selenocysteine moiety of glutathione peroxidase  

SciTech Connect

The selenium in mammalian glutathione peroxidase is present as a selenocysteine ((Se)Cys) moiety incorporated into the peptide backbone 41-47 residues from the N-terminal end. To study the origin of the skeleton of the (Se)Cys moiety, we perfused isolated rat liver with /sup 14/C- or /sup 3/H-labeled amino acids for 4 h, purified the GSH peroxidase, derivatized the (Se)Cys in GSH peroxidase to carboxymethylselenocysteine ((Se)Cys(Cm)), and determined the amino acid specific activity. Perfusion with (/sup 14/C)cystine resulted in (/sup 14/C)cystine incorporation into GSH peroxidase without labeling (Se)Cys(Cm), indicating that cysteine is not a direct precursor for (Se)Cys. (/sup 14/C)Serine perfusion labeled serine, glycine (the serine hydroxymethyltransferase product), and (Se)Cys(Cm) in purified GSH peroxidase, whereas (3-3H)serine perfusion only labeled serine and (Se)Cys(Cm), thus demonstrating that the (Se)Cys in GSH peroxidase is derived from serine. The similar specific activities of serine and (Se)Cys(Cm) strongly suggest that the precursor pool of serine used for (Se) Cys synthesis is the same or similar to the serine pool used for acylation of seryl-tRNAs.

Sunde, R.A.; Evenson, J.K.

1987-01-15

63

Inhibitors and inactivators of serine proteases  

SciTech Connect

Inactivation of chymotrypsin by 3-benzyl-6-chloro-2-pyrone results in the formation of a covalent adduct in which the ..gamma..-oxygen of serine-195 is covalently attached to C-1 of (Z)-2-benzyl-pentenedioic acid. The carboxylate group of the inhibitor forms a salt bridge with histidine-57 and this prevents access of water to the active site. The structure was established through NMR and x-ray diffraction analysis at 1.9 A resolution. Fluoromethyl-ketones are inhibitors of chymotrypsin and pancreatic elastase. /sup 19/F NMR shows that the carbonyl-carbon of the enzyme bound inhibitor is tetrahedral, most probably, due to adduct formation with the active site serine. The efficacy of these inhibitors increases with the number of fluorine substituents and with increasing length of the peptide. For the elastase inhibitor AcProAlaCF/sub 3/ K/sub i/ = 3 x 10/sup -3/ M and for AcAlaAlaProAlaCF/sub 3/ K/sub i/ = 0.34 x 10/sup -6/ M. For the tetrapeptide k/sub on/ = 290 s/sup -1/ M/sup -1/. The lowering of K/sub i/ concomitant with structural change correlates well with the variation in V/K for the corresponding substrates. AcLeuPheCFH/sub 2/ is a weak inhibitor of chymotrypsin, K/sub i/ = 0.28 x 10/sup -3/ M, which irreversibly inactivates the enzyme by alkylating a histidine.

Abeles, R.H.

1986-05-01

64

The 4 Ps as a Guiding Perspective  

ERIC Educational Resources Information Center

|A 4 Ps perspective addresses immediate needs: to help institutions gain traction in their retention strategies by framing and reframing the challenges and the possible responses, by challenging some of the traditional mental models about retention that can distract or dilute those strategies, and by offering focus and coherence to institutional…

Kalsbeek, David H.

2013-01-01

65

Beyond metric gravity: Progress on PS-200  

SciTech Connect

The reconciliation of quantum mechanics and gravity on varying distance scales requires changes to General Relativity that may be testable implications. We briefly review the status of tests with matter of the inverse square law and the principle of equivalence, then report on progress on the drift-tube measurement section of PS- 200, the experiment to measure the gravitational acceleration of antiprotons.

Goldman, T.; Brown, R.E.; Camp, J.B.; Darling, T.; Dyer, P.; Holzscheiter, M.H.; Hughes, R.J.; Jarmie, N.; King, N.S.P.; Lizon, D.C.; Nieto, M.M.; Schauer, M.M.M.; Schecker, J.A. [Los Alamos National Lab., NM (United States); Cornford, S.; Hosea, K.; Kenefick, R.A. [Texas A and M Univ., College Station, TX (United States); Hoibraaten, S.; Midzor, M.M.; Parry, S.P.; Ristenen, R.A. [Colorado Univ., Boulder, CO (United States); Witteborn, F.C. [National Aeronautics and Space Administration, Moffett Field, CA (United States). Ames Research Center; Rochet, J. [European Organization for Nuclear Research, Geneva (Switzerland)

1993-03-01

66

Beyond metric gravity: Progress on PS-200  

SciTech Connect

The reconciliation of quantum mechanics and gravity on varying distance scales requires changes to General Relativity that may be testable implications. We briefly review the status of tests with matter of the inverse square law and the principle of equivalence, then report on progress on the drift-tube measurement section of PS- 200, the experiment to measure the gravitational acceleration of antiprotons.

Goldman, T.; Brown, R.E.; Camp, J.B.; Darling, T.; Dyer, P.; Holzscheiter, M.H.; Hughes, R.J.; Jarmie, N.; King, N.S.P.; Lizon, D.C.; Nieto, M.M.; Schauer, M.M.M.; Schecker, J.A. (Los Alamos National Lab., NM (United States)); Cornford, S.; Hosea, K.; Kenefick, R.A. (Texas A and M Univ., College Station, TX (United States)); Hoibraaten, S.; Midzor, M.M.; Parry, S.P.; Ristenen, R.A. (Colorado Univ., Boulder, CO (U

1993-01-01

67

Positron Annihilation in the Bipositronium Ps2  

SciTech Connect

The electron-positron-pair annihilation in the bipositronium PS2 is considered. In particular, the two-, three-, one- and zero-photon annihilation rates are determined to high accuracy. The corresponding analytical expressions are also presented. Also, a large number of bound state properties have been determined for this system.

Bailey, David H.; Frolov, Alexei M.

2005-07-01

68

10th Anniversary P.S.  

ScienceCinema

John Adams parle de la préhistoire du P.S. avec présentation des dias. Le DG B.Gregory prend la parole. Les organisateurs présentent sous la direction du "Prof.Ocktette"(?) un sketch très humoristique (p.e.existence de Quark etc.....)

69

ORAL SUPPLEMENTATION AND COGNITIVE FUNCTION IN THE ELDERLY: REVIEW ARTICLE \\  

Microsoft Academic Search

OBJECTIVE: We review the experimental evaluations of several widely marketed nonprescription com- pounds claimed to be memory enhancers and treatments for age-related memory decline. We generally limit our review to double-blind placebo-controlled studies. The compounds examined are phosphatidyl- serine (PS), phosphatidylcholine (PC), citicoline, piracetam, vinpocetine, acetyl-L-carnitine (ALC), and antioxidants (particularly vitamin E). RESULTS: In animals, PS has been shown to

Mark A. McDaniel; Steven F. Maier; Gilles O. Einstein

70

D-Serine Regulation of NMDA Receptor Activity  

NSDL National Science Digital Library

The N-Methyl-D-aspartate–type glutamate receptor (NMDAR) plays a key role in several important processes involving the nervous system, including brain development, synaptic plasticity, and learning. Unlike other neurotransmitter receptors, which are activated by individual neurotransmitters, activation of NMDARs requires the binding of a coagonist (D-serine or glycine) in addition to glutamate. Although previously considered an "unnatural" amino acid, D-serine is a key regulator of NMDAR activity and may be the main physiological ligand at the coagonist site. D-Serine is synthesized in the mammalian brain and is enriched in astrocytes, a class of glial cells that ensheath synapses in the brain. Astrocytes physiologically affect NMDAR neurotransmission by releasing D-serine, suggesting that D-serine acts as a gliotransmitter. However, recent findings indicate that D-serine signaling does not depend solely on glia, because D-serine and its biosynthetic enzyme are also present in substantial amounts in neurons. Here, we discuss these new findings, which begin to shed light on the relative roles of glia and neurons in D-serine signaling.

Herman Wolosker (Technion-Israel Institute of Technology;Department of Biochemistry REV)

2006-10-10

71

The Implantation Serine Proteinases: Potential Therapeutic Footholds in Female Fertility  

Microsoft Academic Search

Hatching of the blastocyst from the zona pelluc- ida represents an important first step in implan- tation and the establishment of a successful pregnancy. Investigation in the mouse model system has revealed two serine proteinase systems associated with hatching: strypsin, a localized blastocytic enzyme responsible for the focal hatching of the embryo in vitro; and lysin, a uterine lumenal serine

Derrick E. Rancourt

2001-01-01

72

Micrococcineae serine protease polypeptides and compositions thereof  

US Patent & Trademark Office Database

The present invention provides novel serine proteases, novel genetic material encoding these enzymes, and proteolytic proteins obtained from Micrococcineae spp., including but not limited to Cellulomonas spp. and variant proteins developed therefrom. In particular, the present invention provides protease compositions obtained from a Cellulomonas spp, DNA encoding the protease, vectors comprising the DNA encoding the protease, host cells transformed with the vector DNA, and an enzyme produced by the host cells. The present invention also provides cleaning compositions (e.g., detergent compositions), animal feed compositions, and textile and leather processing compositions comprising protease(s) obtained from a Micrococcineae spp., including but not limited to Cellulomonas spp. In alternative embodiments, the present invention provides mutant (i.e., variant) proteases derived from the wild-type proteases described herein. These mutant proteases also find use in numerous applications.

Jones; Brian E. (Leidschendam, NL); Kolkman; Marc (Oegstgeest, NL); Leeflang; Chris (The Hague, NL); Oh; Hiroshi (Cincinnati, OH); Poulose; Ayrookaran J. (Belmont, CA); Sadlowski; Eugene S. (Cincinnati, OH); Shaw; Andrew (San Francisco, CA); van Marrewijk; Leo (Zoetermeer, NL); Van Der Kleij; Wilhelmus A. H. (The Hague, NL)

2013-09-17

73

The External Aldimine Form of Serine Palmitoyltransferase  

PubMed Central

Sphingolipid biosynthesis begins with the condensation of l-serine and palmitoyl-CoA catalyzed by the PLP-dependent enzyme serine palmitoyltransferase (SPT). Mutations in human SPT cause hereditary sensory autonomic neuropathy type 1, a disease characterized by loss of feeling in extremities and severe pain. The human enzyme is a membrane-bound hetereodimer, and the most common mutations are located in the enzymatically incompetent monomer, suggesting a “dominant” or regulatory effect. The molecular basis of how these mutations perturb SPT activity is subtle and is not simply loss of activity. To further explore the structure and mechanism of SPT, we have studied the homodimeric bacterial enzyme from Sphingomonas paucimobilis. We have analyzed two mutants (N100Y and N100W) engineered to mimic the mutations seen in hereditary sensory autonomic neuropathy type 1 as well as a third mutant N100C designed to mimic the wild-type human SPT. The N100C mutant appears fully active, whereas both N100Y and N100W are significantly compromised. The structures of the holoenzymes reveal differences around the active site and in neighboring secondary structure that transmit across the dimeric interface in both N100Y and N100W. Comparison of the l-Ser external aldimine structures of both native and N100Y reveals significant differences that hinder the movement of a catalytically important Arg378 residue into the active site. Spectroscopic analysis confirms that both N100Y and N100W mutants subtly affect the chemistry of the PLP. Furthermore, the N100Y and R378A mutants appear less able to stabilize a quinonoid intermediate. These data provide the first experimental insight into how the most common disease-associated mutations of human SPT may lead to perturbation of enzyme activity.

Raman, Marine C. C.; Johnson, Kenneth A.; Yard, Beverley A.; Lowther, Jonathan; Carter, Lester G.; Naismith, James H.; Campopiano, Dominic J.

2009-01-01

74

Purification and properties of phosphatidyl-N-monomethylethanolamine N-methyltransferase, the enzyme catalyzing the second and the third steps in the phosphatidylethanolamine N-methyltransferase system, from mouse liver microsomes.  

PubMed

The phosphatidylethanolamine (PE) N-methyltransferase (MT) system is known to convert PE to phosphatidylcholine by three successive N-methylations. Phosphatidyl-N-monomethylethanolamine (PME) MT was purified 1,400-fold from mouse liver microsomes and separated from the PE-MT activity for the first time. This enzyme catalyzes N-methylations of PME and phosphatidyl-N,N-dimethylethanolamine, the intermediates of PE-MT system, but not PE, the initial substrate of the PE-MT system. In addition, a preparation with a different affinity to S-adenosyl-L-homocysteine catalyzing all the three methylations was obtained. These results suggest that at least two enzymes are involved in the PE-MT system. PMID:2126577

Tanaka, Y; Amano, F; Maeda, M; Nishijima, M; Akamatsu, Y

1990-06-01

75

Phosphorylation of Cdc6 at serine 74, but not at serine 106, drives translocation of Cdc6 to the cytoplasm.  

PubMed

Phosphorylation-dependent cytoplasmic translocation of human Cdc6 during S phase is sufficient to control its activity after origin firing. Export from the nucleus also serves as a mechanism for preventing re-replication in mammalian cells. Phosphorylation of the CDK consensus serine residues 54, 74, and 106 has been suggested to be involved in the cytoplasmic translocation of Cdc6. To determine the relative importance of the three phosphorylation sites, we have generated Cdc6 variants by substituting one or more of the three serine residues with alanine or aspartic acid and have assessed their cytoplasmic translocation behavior. Phosphorylation of serine 74 mainly contributes to the cytoplasmic translocation of Cdc6, while serine 54 phosphorylation provides a minor contribution. In contrast, phosphorylation at serine 106 does not affect the nuclear export of Cdc6. Comparative results were found in cells coexpressing the phosphorylation defective mutants of Cdc6 and cyclin A as well as in non-transfected cells synchronized by their release from a double thymidine block. We conclude that Cdk-mediated phosphorylation of Cdc6 at serine 74 is required for the cytoplasmic translocalization of Cdc6 during the cell cycle. Phosphorylation of Cdc6 at serine 54 plays a minor role and phosphorylation of serine 106 plays no role in the cytoplasmic localization of Cdc6. The phosphorylation of S74 in Cdc6 could be important for binding to the nuclear export protein for translocalization. PMID:23129444

Yim, Hyungshin; Park, Ji-Woong; Woo, Sang Uk; Kim, Seong-Taek; Liu, Linhua; Lee, Chul-Hoon; Lee, Seung Ki

2013-06-01

76

Phase Behavior of PS-PVME Nanocomposites  

Microsoft Academic Search

The influence of nanometer thick, highly anisotropic organically modified layered silicate (montmorillonite) on the phase behavior of deuterated polystyrene (dPS) and poly(vinyl methyl ether) (PVME) is investigated by a combination of small-angle neutron scattering (SANS) and a two-dimensional combinatorial method based on light scattering and corroborated by single-point static cloud-point light scattering. The presence of layered silicates up to a

Koray Yurekli; Alamgir Karim; Eric J. Amis; Ramanan Krishnamoorti

2004-01-01

77

High-Redshift Quasars from PS1  

Microsoft Academic Search

We present the High-Redshift Quasar (HZQ) key project of the PS1 Science Consortium. Using the Pan-STARRS 1 telescope and its GigaPixel Camera, we will identify hundreds of quasars at z 6 (z-band dropouts), and tens of quasars at y 7 (y-band dropouts). These samples will be used to characterise the population of accreting black holes and their host galaxies in

Paul A. Price; K. C. Chambers; S. Jester; F. Walter

2007-01-01

78

Intrinsic Viscosity Characterization of PS and PMMA  

NSDL National Science Digital Library

In this experiment, you will use intrinsic viscosity measurements to determine the molecular weight of polystyrene, PS, or poly(methyl methacrylate), PMMA. After in-class presentation, completion of hands-on laboratory experiment and review of the information provided, you should be able to: ⢠Identify several laboratory methods for molecular weight analysis of polymers. ⢠Confidently discuss the differences between the methods of analysis for polymer molecular weight. ⢠Discuss how polymer solution behavior affects molecular weight measurements.

Derosa, Rebecca L.

2008-09-26

79

The HARP detector at the CERN PS  

Microsoft Academic Search

HARP is a high-statistics, large solid angle experiment to measure hadron production using proton and pion beams with momenta between 1.5 and 15GeV\\/c impinging on many different solid and liquid targets from low to high Z. The experiment, located in the T9 beam of the CERN PS, took data in 2001 and 2002. For the measurement of momenta of produced

M. G. Catanesi; M. T. Muciaccia; E. Radicioni; S. Simone; R. Edgecock; M. Ellis; S. Robbins; F. J. P. Soler; C. Gößling; M. Mass; S. Bunyatov; A. Chukanov; O. Klimov; I. Krasin; A. Krasnoperov; D. Kustov; B. Popov; V. Serdiouk; V. Tereshchenko; V. Carassiti; E. Di Capua; F. Evangelisti; G. Vidal-Sitjes; A. Artamonov; P. Arce; R. Brocard; G. Decreuse; B. Friend; S. Giani; S. Gilardoni; P. Gorbunov; A. Grant; A. Grossheim; P. Gruber; V. Ivanchenko; J.-C. Legrand; A. Kayis-Topaksu; J. Panman; I. Papadopoulos; J. Pasternak; E. Tcherniaev; I. Tsukerman; R. van der Vlugt; R. Veenhof; C. Wiebusch; P. Zucchelli; A. Blondel; S. Borghi; M. Campanelli; A. Cervera-Villanueva; M. C. Morone; G. Prior; R. Schroeter; I. Kato; U. Gastaldi; G. B. Mills; J. S. Graulich; G. Grégoire; M. Bonesini; F. Chignoli; F. Ferri; F. Paleari; M. Kirsanov; V. Postoev; A. Bagulya; V. Grichine; N. Polukhina; V. Palladino; L. Coney; D. Schmitz; G. Barr; A. De Santo; C. Pattison; K. Zuber; G. Barichello; F. Bobisut; D. Gibin; A. Guglielmi; M. Laveder; A. Menegolli; M. Mezzetto; A. Pepato; J. Dumarchez; S. Troquereau; F. Vannucci; U. Dore; A. Iaciofano; M. Lobello; F. Marinilli; D. Orestano; D. Panayotov; M. Pasquali; F. Pastore; A. Tonazzo; L. Tortora; C. Booth; C. Buttar; P. Hodgson; L. Howlett; R. Nicholson; M. Bogomilov; K. Burin; M. Chizhov; D. Kolev; P. Petev; I. Rusinov; R. Tsenov; S. Piperov; P. Temnikov; M. Apollonio; P. Chimenti; G. Giannini; G. Santin; J. Burguet-Castell; J. J. Gómez-Cadenas; P. Novella; M. Sorel; A. Tornero

2007-01-01

80

Towards a Balanced View on iPS Cells  

Microsoft Academic Search

ABSTRACT In the past one and half years scientific community,and general public have been excited with the discovery of induced pluripotent stem (iPS) cells. However, how much truth is contained in the various claims made for iPS cells? What are these iPS cells? Are they really safe for therapeutic use? This review attempts to present a balanced view on iPS

Shi V. Liu

2008-01-01

81

Discovery of supernovae in the PS1 sky survey  

Microsoft Academic Search

On behalf of the PS1 Science Consortium, we report the discovery of 9 supernovae in the Pan-STARRS Telescope #1 (PS1) sky survey. Images from PS1 Medium-Deep-Fields 7 and 8 were processed and differenced by the PS1 Image Processing Pipeline and detections were filtered with prototype modules of the Transient Science Server at CfA and QUB.

D. Young; S. Valenti; A. Rest; G. Narayan; M. Huber; S. Gezari; S. Rodney; C. Trundle; K. Smith; S. Smartt; P. Price; C. Stubbs J. Tonry; A. Riess; W. M. Wood-Vasey; M. T. Botticella; A. Pastorello; R. Kotak; M. Fraser; D. Hunter; K. Maguire; R. Foley

2009-01-01

82

Fibrin(ogen)olytic activity of bumblebee venom serine protease  

SciTech Connect

Bee venom is a rich source of pharmacologically active components; it has been used as an immunotherapy to treat bee venom hypersensitivity, and venom therapy has been applied as an alternative medicine. Here, we present evidence that the serine protease found in bumblebee venom exhibits fibrin(ogen)olytic activity. Compared to honeybee venom, bumblebee venom contains a higher content of serine protease, which is one of its major components. Venom serine proteases from bumblebees did not cross-react with antibodies against the honeybee venom serine protease. We provide functional evidence indicating that bumblebee (Bombus terrestris) venom serine protease (Bt-VSP) acts as a fibrin(ogen)olytic enzyme. Bt-VSP activates prothrombin and directly degrades fibrinogen into fibrin degradation products. However, Bt-VSP is not a plasminogen activator, and its fibrinolytic activity is less than that of plasmin. Taken together, our results define roles for Bt-VSP as a prothrombin activator, a thrombin-like protease, and a plasmin-like protease. These findings offer significant insight into the allergic reaction sequence that is initiated by bee venom serine protease and its potential usefulness as a clinical agent in the field of hemostasis and thrombosis. - Graphical abstract: Display Omitted Highlights: > Bumblebee venom serine protease (Bt-VSP) is a fibrin(ogen)olytic enzyme. > Bt-VSP activates prothrombin. > Bt-VSP directly degrades fibrinogen into fibrin degradation products. > Bt-VSP is a hemostatically active protein that is a potent clinical agent.

Qiu Yuling [College of Natural Resources and Life Science, Dong-A University, Busan 604-714 (Korea, Republic of); Joint Laboratory between Dong-A University and Shenyang Pharmaceutical University, Shenyang Pharmaceutical University, Shenyang (China); Choo, Young Moo [College of Natural Resources and Life Science, Dong-A University, Busan 604-714 (Korea, Republic of); Yoon, Hyung Joo [Department of Agricultural Biology, National Academy of Agricultural Science, Suwon (Korea, Republic of); Jia Jingming; Cui Zheng; Wang Dong [Joint Laboratory between Dong-A University and Shenyang Pharmaceutical University, Shenyang Pharmaceutical University, Shenyang (China); Kim, Doh Hoon [College of Natural Resources and Life Science, Dong-A University, Busan 604-714 (Korea, Republic of); Joint Laboratory between Dong-A University and Shenyang Pharmaceutical University, Shenyang Pharmaceutical University, Shenyang (China); Sohn, Hung Dae [College of Natural Resources and Life Science, Dong-A University, Busan 604-714 (Korea, Republic of); Jin, Byung Rae, E-mail: brjin@dau.ac.kr [College of Natural Resources and Life Science, Dong-A University, Busan 604-714 (Korea, Republic of); Joint Laboratory between Dong-A University and Shenyang Pharmaceutical University, Shenyang Pharmaceutical University, Shenyang (China)

2011-09-01

83

Catabolism of serine by Pediococcus acidilactici and Pediococcus pentosaceus.  

PubMed

The ability to produce diacetyl from pyruvate and l-serine was studied in various strains of Pediococcus pentosaceus and Pediococcus acidilactici isolated from cheese. After being incubated on both substrates, only P. pentosaceus produced significant amounts of diacetyl. This property correlated with measurable serine dehydratase activity in cell extracts. A gene encoding the serine dehydratase (dsdA) was identified in P. pentosaceus, and strains that showed no serine dehydratase activity carried mutations that rendered the gene product inactive. A functional dsdA was cloned from P. pentosaceus FAM19132 and expressed in Escherichia coli. The purified recombinant enzyme catalyzed the formation of pyruvate from L- and D-serine and was active at low pH and elevated NaCl concentrations, environmental conditions usually present in cheese. Analysis of the amino acid profiles of culture supernatants from dsdA wild-type and dsdA mutant strains of P. pentosaceus did not show differences in serine levels. In contrast, P. acidilactici degraded serine. Moreover, this species also catabolized threonine and produced alanine and ?-aminobutyrate. PMID:23241976

Irmler, Stefan; Bavan, Tharmatha; Oberli, Andrea; Roetschi, Alexandra; Badertscher, René; Guggenbühl, Barbara; Berthoud, Hélène

2012-12-14

84

Catabolism of Serine by Pediococcus acidilactici and Pediococcus pentosaceus  

PubMed Central

The ability to produce diacetyl from pyruvate and l-serine was studied in various strains of Pediococcus pentosaceus and Pediococcus acidilactici isolated from cheese. After being incubated on both substrates, only P. pentosaceus produced significant amounts of diacetyl. This property correlated with measurable serine dehydratase activity in cell extracts. A gene encoding the serine dehydratase (dsdA) was identified in P. pentosaceus, and strains that showed no serine dehydratase activity carried mutations that rendered the gene product inactive. A functional dsdA was cloned from P. pentosaceus FAM19132 and expressed in Escherichia coli. The purified recombinant enzyme catalyzed the formation of pyruvate from l- and d-serine and was active at low pH and elevated NaCl concentrations, environmental conditions usually present in cheese. Analysis of the amino acid profiles of culture supernatants from dsdA wild-type and dsdA mutant strains of P. pentosaceus did not show differences in serine levels. In contrast, P. acidilactici degraded serine. Moreover, this species also catabolized threonine and produced alanine and ?-aminobutyrate.

Bavan, Tharmatha; Oberli, Andrea; Roetschi, Alexandra; Badertscher, Rene; Guggenbuhl, Barbara; Berthoud, Helene

2013-01-01

85

Synthesis of o-L-? -glycerylphosphoryl- L -serine  

Microsoft Academic Search

A new efficient method for preparing o-L-?-glycerylphosphoryl-L-serine was presented. D-?, ?-isopropylidene glycerol was phosphorylated with phenylphosphoryl dichloride and the resulting o-D-?,?-isopropylidene glycerylphenylphosphoryl chloride was esterified with N-tert-butoxycarbonyl-L-serine ethyl ester in the presence of pyridine to give acetone L-?-glycerylphenylphosphoryl-N-tert-butoxycarbonyl-L-serine ethyl ester. Finally, the protective groups were removed by two-step hydrolysis while strictly controlling pH value.\\u000a The reaction to produce (1, 2),

Rui-ren Tang; Zi-er Yan; Yi-ming Luo

2005-01-01

86

CDK8 as the STAT1 serine 727 kinase?  

PubMed Central

Whereas cytokine-induced tyrosine phosphorylation of STAT (signal transducer and activator of transcription) proteins by JAK kinases has been well studied, much less is known about STAT-specific serine kinases and their signal-dependent regulation. The paper by Joanna Bancerek and colleagues published recently in Immunity reports that upon interferon-? (IFN?) stimulation of cells the chromatin-associated cyclin-dependent kinase 8 (CDK8) phosphorylates the regulatory serine residue 727 in the transactivation domain of STAT1. The authors state that the CDK8 module of the Mediator complex is a key component in the STAT1 signal pathway, linking serine phosphorylation to gene-specific transcriptional events.

Staab, Julia; Herrmann-Lingen, Christoph; Meyer, Thomas

2013-01-01

87

Requirement for calcium ions in acetylcholine-stimulated phosphodiesteratic cleavage of phosphatidyl-myo-inositol 4,5-bisphosphate in rabbit iris smooth muscle  

PubMed Central

1. The mechanism of acetylcholine-stimulated breakdown of phosphatidyl-myo-inositol 4,5-bisphosphate and its dependence on extracellular Ca2+ was investigated in the rabbit iris smooth muscle. 2. Acetylcholine (50?m) increased the breakdown of phosphatidylinositol bisphosphate in [3H]inositol-labelled muscle by 28% and the labelling of phosphatidylinositol by 24% of that of the control. Under the same experimental conditions there was a 33 and 48% increase in the production of 3H-labelled inositol trisphosphate and inositol monophosphate respectively. Similarly carbamoylcholine and ionophore A23187 increased the production of these water-soluble inositol phosphates. Little change was observed in the 3H radioactivity of inositol bisphosphate. 3. Both inositol trisphosphatase and inositol monophosphatase were demonstrated in subcellular fractions of this tissue and the specific activity of the former was severalfold higher than that of the latter. 4. The acetylcholine-stimulated production of inositol trisphosphate and inositol monophosphate was inhibited by atropine (20?m), but not tubocurarine (100?m); and it was abolished by depletion of extracellular Ca2+ with EGTA, but restored on addition of low concentrations of Ca2+ (20?m). 5. Calcium-antagonistic agents, such as verapamil (20?m), dibenamine (20?m) or La3+ (2mm), also abolished the production of the water-soluble inositol phosphates in response to acetylcholine. 6. Release of inositol trisphosphate from exogenous phosphatidylinositol bisphosphate by iris muscle microsomal fraction (`microsomes') was stimulated by 43% in the presence of 50?m-Ca2+. 7. The results indicate that increased Ca2+ influx into the iris smooth muscle by acetylcholine and ionophore A23187 markedly activates phosphatidylinositol bisphosphate phosphodiesterase and subsequently increases the production of inositol trisphosphate and its hydrolytic product inositol monophosphate. The marked increase observed in the production of inositol monophosphate could also result from Ca2+ activation of phosphatidylinositol phosphodiesterase. However, there was no concomitant decrease in the 3H radioactivity of this phospholipid.

Akhtar, Rashid A.; Abdel-Latif, Ata A.

1980-01-01

88

Novel Serine Protease Inhibitors and Genes Encoding Same.  

National Technical Information Service (NTIS)

The present invention is related to the identification of genes which encode proteins having substantial degree of homology to the serine protease inhibitor superfamily. There are no known synthetic or microbial proteins capable of specifically inhibiting...

G. J. Kotwal B. Moss

1988-01-01

89

Targeted disruption of serine racemase affects glutamatergic neurotransmission and behavior  

PubMed Central

A subset of glutamate receptors that are specifically sensitive to the glutamate analog N-methyl-D-aspartate (NMDA) are molecular coincidence detectors, necessary for activity-dependent processes of neurodevelopment and in sensory and cognitive functions. The activity of these receptors is modulated by the endogenous amino acid D-serine, but the extent to which D-serine is necessary for the normal development and function of the mammalian nervous system was previously unknown. Decreased signaling at NMDA receptors has been implicated in the pathophysiology of schizophrenia based on pharmacological evidence, and several human genes related to D-serine metabolism and glutamatergic neurotransmission have been implicated in the etiology of schizophrenia. Here we show that genetically modified mice lacking the ability to produce D-serine endogenously have profoundly altered glutamatergic neurotransmission, and relatively subtle but significant behavioral abnormalities that reflect hyperactivity and impaired spatial memory, and that are consistent with elevated anxiety.

Basu, Alo C.; Tsai, Guochuan E.; Ma, Chun-Lei; Ehmsen, Jeffrey T.; Mustafa, Asif K.; Han, Liqun; Jiang, Zhichun I.; Benneyworth, Michael A.; Froimowitz, Michael P.; Lange, Nicholas; Snyder, Solomon H.; Bergeron, Richard; Coyle, Joseph T.

2009-01-01

90

The Pharmacological Landscape and Therapeutic Potential of Serine Hydrolases  

PubMed Central

Serine hydrolases play critical roles in many biological processes, and several are targets of approved drugs for indications such as type 2 diabetes, Alzheimer’s disease, and infectious disease. Despite this, most of the 200+ human serine hydrolases remain poorly characterized with respect to their physiological substrates and functions, and the vast majority lack selective, in vivo-active inhibitors. Here, we review the current state of pharmacology for mammalian serine hydrolases, including marketed drugs, compounds under clinical investigation, and selective inhibitors emerging from academic probe development efforts. We also highlight recent methodological advances that have accelerated the rate of inhibitor discovery and optimization for serine hydrolases, which we anticipate will aid in their biological characterization and, in some cases, therapeutic validation.

Bachovchin, Daniel A.; Cravatt, Benjamin F.

2013-01-01

91

Fatal cerebral edema associated with serine deficiency in CSF  

Microsoft Academic Search

Two young girls without a notable medical history except for asthma presented with an acute toxic encephalopathy with very\\u000a low serine concentrations both in plasma and cerebrospinal fluid (CSF) comparable to patients with 3-phosphoglycerate dehydrogenase\\u000a (3-PGDH) deficiency. Clinical symptoms and enzyme measurement (in one patient) excluded 3-PGDH deficiency. Deficiencies in\\u000a other serine biosynthesis enzymes were highly unlikely on clinical grounds.

Irene M. L. W. Keularts; Piet L. J. M. Leroy; Estela M. Rubio-Gozalbo; Leo J. M. Spaapen; Biene Weber; Bert Dorland; Tom J. de Koning; Nanda M. Verhoeven-Duif

92

Regulation of genes encoding PS I and PS II proteins in Synechocystis  

SciTech Connect

The mechanisms of regulation of the genes encoding PS I and PS II components are largely unknown for the unicellular cyanobacterium Synechocystis sp. PCC 6803. In an attempt to elucidate how PS I and PS II biogenesis is controlled, we have isolated RNA from cells grown in various light conditions and analyzed relative steady-state levels of transcripts on Northern blots. Results from blots probed with psaA and psaB (which we recently cloned and sequenced) as well as previously isolated clones for psbA1, psbA2, psbD2, psaD, rbcL, and rrn will be presented. Preliminary data indicate the psbA and psaA-psaB transcripts accumulate in cells put in the dark, although the psaA-psaB transcript levels are somewhat reduced in the dark. Future experiments will focus on molecular analysis of the promoter region for the psaA-psaB operon.

Smart, L.B.; McIntosh, L. (Michigan State Univ., East Lansing (USA))

1990-05-01

93

The Glasscock Site, 34-Ps-96 and Two Other Prehistoric Sites in Pittsburg County, Oklahoma.  

National Technical Information Service (NTIS)

Archaeological sites Ps-86, Ps-88, and Ps-96 have been tested by the Oklahoma Conservation Commission. These tests indicated Ps-86 and Ps-88 are minor sites that were only minimally used. Site Ps-96 however, may represent an intensive occupation with comp...

D. T. Hughes

1978-01-01

94

S-Wave Shape Resonances in the Ps- System  

NASA Astrophysics Data System (ADS)

We have investigated the S-wave shape resonance states of the positronium negative ion (Ps-) system. The resonance poles are traced from H- system to Ps- by systematically varying the mass of the positively charged particle from infinitely heavy to one unit of the electron mass. The shape resonances that associated with and lying above the Ps( N = 2, 3, 4 and 5) thresholds are located by employing the complex-coordinate rotation method with highly correlated Hylleraas-type wave functions. It has been shown that the Ps-( N = 3) shape resonance lies at an energy which is higher than the Ps( N = 4) thresholds and even the Ps-( N = 4) shape resonance. An explanation was given to shed light on such phenomena.

Jiao, L. G.; Ho, Y. K.

2013-11-01

95

Covalent structure of human haptoglobin: a serine protease homolog.  

PubMed Central

The complete amino acid sequences and the disulfide arrangements of the two chains of human haptoglobin 1-1 were established. The alpha 1 and beta chains of haptoglobin contain 83 and 245 residues, respectively. Comparison of the primary structure of haptoglobin with that of the chymotrypsinogen family of serine proteases revealed a significant degree of chemical similarity. The probability was less than 10(-5) that the chemical similarity of the beta chain of haptoglobin to the proteases was due to chance. The amino acid sequence of the beta chain of haptoglobin is 29--33% identical to bovine trypsin, bovine chymotrypsin, porcine elastase, human thrombin, or human plasmin. Comparison of haptoglobin alpha 1 chain to activation peptide regions of the zymogens revealed an identity of 25% to the fifth "kringle" region of the activation peptide of plasminogen. The probability was less than 0.014 that this similarity was due to chance. These results strongly indicate haptoglobin to be a homolog of the chymotrypsinogen family of serine proteases. Alignment of the beta-chain sequence of haptoglobin to the serine proteases is remarkably consistent except for an insertion of 16 residues in the region corresponding to the methionyl loop of the serine proteases. The active-site residues typical of the serine proteases, histidine-57 and serine-195, are replaced in haptoglobin by lysine and alanine, respectively; however, aspartic acid-102 and the trypsin specificity, residue, aspartic acid-189, do occur in haptoglobin. Haptoglobin and the serine proteases represent a striking example of homologous proteins with different biological functions.

Kurosky, A; Barnett, D R; Lee, T H; Touchstone, B; Hay, R E; Arnott, M S; Bowman, B H; Fitch, W M

1980-01-01

96

Iron deficiency reduces the hydrolysis of cell membrane phosphatidyl inositol-4,5-bisphosphate during splenic lymphocyte activation in C57BL/6 mice.  

PubMed

Iron deficiency impairs lymphocyte proliferation in humans and laboratory animals by unknown mechanisms. In this study, we investigated whether this alteration can be attributed in part to impaired hydrolysis of cell membrane phosphatidyl inositol-4, 5-bisphosphate (PIP2), a required early event of T-lymphocyte activation. The study involved 46 iron-deficient (ID), 26 control (C) and 23 pair-fed (PF) mice, and ID mice that were repleted for 3 (n = 16), 7 (n = 17) or 14 d (n = 18). Mice were killed after 40-63 d (mean, 48 d) of consuming the test diet (0.09 mmol/kg iron) or the control diet (0.9 mmol/kg). The mean (+/-SEM) hemoglobin concentrations were 57 +/- 16.7, 176 +/- 2.6 and 181 +/- 9.7 g/L for ID, C and PF groups, respectively. After splenic lymphocytes were labeled in vitro with 3H-myoinositol for 3 h, PIP2 hydrolysis was estimated by measuring the radioactivity recovered as a mixture of inositol mono-, di- and triphosphate (IP) from concanavalin A (0, 1, 2.5, 5 and 10 mg/L) activated cells. Although cells from ID mice and those from mice repleted for 3 d incorporated slightly more radioactivity in cellular phospholipids than did cells from C or PF mice, less (P < 0.005) was recovered as IP than in controls, suggesting impaired conversion of the precursor to PIP2. At almost all incubation periods (10-120 min) and mitogen concentrations, the rate of PIP2 hydrolysis expressed as the ratio of radioactivity obtained in Con A-treated to untreated cells was significantly (P < 0.05) reduced in cells from ID mice compared with those obtained from C and PF mice. For cells that were activated for 60 min or less, iron repletion for 14 d significantly (P < 0.05) improved the rate of PIP2 hydrolysis. PIP2 hydrolysis positively and significantly (P < 0.05) correlated (r = 0.27-0.56) with indicators of iron status. Mitogenic response was also significantly (P < 0.05) reduced in ID but not PF mice, and it was corrected by iron repletion for 3, 7 or 14 d. Lymphocyte proliferation positively (r = 0.27-0.37, P < 0.01) correlated with indices of iron status and IP ratios. The data suggest that reduced PIP2 hydrolysis contributes to impaired blastogenesis in iron deficiency. PMID:9649588

Kuvibidila, S R; Baliga, B S; Warrier, R P; Suskind, R M

1998-07-01

97

A randomized, double-blind, crossover study on the pharmacokinetics of a novel formulation of CoQ?? with pyridoxal 5'-phosphate and phosphatidyl choline.  

PubMed

The pharmacokinetics of a single 30-mg dose of a novel enteric-coated coenzyme Q10 (CoQ(10)) formulation with pyridoxal 5'-phosphate and phosphatidyl choline (CoQ(10)-P5P-PC) was investigated against two comparators CoQ(10) (NPN 02176955) and CoQ(10) (DIN 02231736) in 21 healthy volunteers, with screening CoQ(10) levels of 0.8 ± 0.2 mg/L. A randomized, double-blind, crossover study was designed with a washout period of 2 weeks between each formulation and blood sampled at 2, 4, 5, 6, 8, 12, 24, 48 and 72 hr postdose. Significantly, higher plasma concentrations were demonstrated for the CoQ(10) (NPN 02176955) formulation at 6 and 8 hr postdose (p = .010 and p = .042, respectively). There were no significant differences between formulations with respect to the area under the curve, AUC((0-72 hr)), or the maximum plasma concentration (C(max)). Total CoQ(10) (T(max)) reached maximum plasma concentrations at 6.4 ± 2.5 hr after supplementation with CoQ(10) (NPN 02176955), 8.0 ± 9.8 hr with CoQ(10)-P5P-PC, and 9.5 ± 9.3 hr with CoQ(10) (DIN 02231736). The estimated elimination half-life (t(1/2)) was 92.3 hr after a single oral dose of CoQ(10)-P5P-PC, 38.2 hr with CoQ(10) (NPN 02176955), and 80.7 hr with CoQ(10) (DIN 02231736). The results suggest that CoQ(10) is available for a longer time in subjects' administered with CoQ(10)-P5P-PC in comparison with the other two formulations studied. There were no significant differences in adverse events, by severity, causality, or organ system. The CoQ(10)-P5P-PC formulation was found to be superior in the t(1/2), and it may be suggested that fewer doses are required to maintain healthy circulatory CoQ(10) levels. PMID:22432561

Evans, Malkanthi; Sharma, Prachi; Guthrie, Najla

2010-10-11

98

Rise time of BC422 plastic scintillator < 20 ps  

Microsoft Academic Search

The rise time of the plastic scintillator BC-422 has been determined to be less than 20 ps. To make the measurement, scintillator excitation was produced by X-ray pulses generated by focusing 20-ps, 2.5-TW laser pulses onto gold targets. Scintillator output was recorded with an optical streak camera whose response is 15 ps. This fast rise time identifies BC-422 as a

R. A. Lerche; D. W. Phillion

1991-01-01

99

Photoinactivation of PS2 secondary donors by PS2 cation radicals and superoxide radicals  

SciTech Connect

Illumination of Mn- and Cl-depleted PS2 causes rapid irreversible inactivation of specific redox-active components on the donor side of the PS2 Reaction Center (RC). Under aerobic conditions, weak light preillumination of NH{sub 2}OH-PS2 causes rapid loss of Y{sub Z}{sup {plus_minus}} formation, Y{sub Z} {yields} P{sub 680}{sup +}, the A{sub T}-band thermoluminescence emission, the Y{sub Z}{sup +}-dependent (Site 1) photooxidation of exogenous e{sup {minus}} donors, and the capability to photoligate Mn{sup 2+} into the water oxidizing enzyme (photoactivation), all without significantly affecting P{sub 680}{sup +}/Q{sub A}{sup {minus}} charge separation. In contrast, aerobic high light preillumination of Mn-depleted PS2 promotes very rapid and parallel loss of photoactivation and A{sub T}-band emission capabilities significantly than loss of either Y{sub Z}{sup +}-formation or P{sub 680}{sup +}/Q{sub A}{sup {minus}} charge separation capabilities. These photodamages and those to Cl-depleted thylakoids (4,5) generally are believed to be caused by reactions between the highly oxidizing cation radicals (P{sub 680}{sup +}/Chl{sup +}) and nearby amino acid residues of D{sub 1}>D{sub 2}. The reported promotion of the photodamages by e{sup {minus}} acceptors of Q{sub A}{sup {minus}}/Q{sub B}{sup {minus}} their inhibition by e{sup {minus}} donors to Y{sub Z}{sup +} and their occurrence under strict anaerobic conditions all tend to support the idea of direct damage by P{sub 680}{sup +}/Chl{sup +}. Our studies lead us to conclude that the photodamages to the donor side components are caused minimally by a rapid mechanism requiring both superoxide and PS2 cation radicals; and by a slower mechanism driven by the PS2 cation radicals only.

Chen, G.X.; Cheniae, G.M. [Kentucky Univ., Lexington, KY (United States); Blubaugh, D.J. [Utah State Univ., Logan, UT (United States); Golbeck, J.H. [Nebraska Univ., Lincoln, NE (United States)

1991-12-31

100

Plasma Motion during the Formation Phase of the PS-3 and PS-3.5 Spheromaks  

NASA Astrophysics Data System (ADS)

Spectroscopic Doppler shift measurements of a CIII impurity ion in the ultraviolet are reported from the University of Maryland spheromak experiments PS-3 and PS-3.5. A new time and space resolved Doppler shift diagnostic with absolute wavelength calibration to +/- 0.02 A is described. The spheromak is a member of the compact toroid class of magnetic confinement devices. Spheromak formation is thought to proceed through a magnetic reconnection or relaxation process characterized by evolution to a minimum energy equilibrium subject to the constraint that the magnetic helicity is invariant. Large velocity fields (on the order of the Alfven speed) observed in both the PS-3 and PS-3.5 experiments during the formation phase, but not during the equilibrium, suggest that flow fields may play an important role in the reconnection and relaxation process. The standard theory of Taylor relaxation may need to be modified in order to include the effects of bulk plasma motion. Doppler shift measurements of the CIII 2296.87 A impurity emission line in the PS-3.5 spheromak were made side-on above and below the machine axis. During the formation phase, blue shifts are observed below and red shifts observed above the axis suggesting a toroidal rotation in the direction of the confined plasma diamagnetic drift. The plasma emissivity near the CIII wavelength was obtained from Abel inversion of the line-integrated intensities. Computer modelling of velocity fields, emissivity profiles and line shapes is used to interpret the experimental data. Variation of the flow fields as a function of the static fill pressure indicated the possible significance of the density profile to bulk motion of the plasma. A quadarature interferometer was used to obtain the time history of the line-integrated density through two chords of the plasma. Double-floating probe measurements gave the radial component of the electric field. The University of Maryland PS experiments utilize a combined theta and z discharge to produce the spheromak magnetic field configuration. The theory of rotation in theta pinch devices is briefly reviewed and a comparison is made with the results of the present experiment. The theoretical implications of including velocity terms in the energy minimization problem are also discussed. The decay rate of an ideal MHD invariant, the cross helicity, is considered in view of viscous and resistive effects in the experiments.

Peyser, Thomas Arnold

101

Genome-wide survey of prokaryotic serine proteases: Analysis of distribution and domain architectures of five serine protease families in prokaryotes  

Microsoft Academic Search

BACKGROUND: Serine proteases are one of the most abundant groups of proteolytic enzymes found in all the kingdoms of life. While studies have established significant roles for many prokaryotic serine proteases in several physiological processes, such as those associated with metabolism, cell signalling, defense response and development, functional associations for a large number of prokaryotic serine proteases are relatively unknown.

Lokesh P Tripathi; R Sowdhamini

2008-01-01

102

LETTER TO THE EDITOR: The stability and structure of Li+Ps2 and Na+Ps2  

NASA Astrophysics Data System (ADS)

The fixed-core stochastic variational method has been used to demonstrate the existence of an electronically stable ground state for the Li+Ps2 and Na+Ps2 systems. The stability of Li+Ps2 has been indicated previously in an ab initio calculation by Varga, but the present estimate of the binding energy is much closer to convergence. The Li+Ps2 system has a binding energy of 0.013 149 Hartree and a 2icons/Journals/Common/gamma" ALT="gamma" ALIGN="TOP"/> annihilation rate of 3.86 × 109 s-1. The Na+Ps2 system has a binding energy of 0.005 736 Hartree and an annihilation rate of 4.02 × 109 s-1. Examination of the interparticle expectation values, correlation functions and the annihilation rates suggests that both of these systems can be best described as a Ps2 molecule weakly bound to an alkali atom cation.

Mitroy, J.; Ryzhikh, G. G.

1999-11-01

103

Overexpression of serine racemase in retina and overproduction of D-serine in eyes of streptozotocin-induced diabetic retinopathy  

PubMed Central

Background Recent data indicate that inflammatory mechanisms contribute to diabetic retinopathy (DR). We have determined that serine racemase (SR) expression is increased by inflammatory stimuli including liposaccharide (LPS), amyloid ?-peptide (A-beta), and secreted amyloid precursor protein (sAPP); expression is decreased by the anti-inflammatory drug, dexamethasone. We tested possibility that SR and its product, D-serine, were altered in a rat model of DR. Methods Intraperitoneal injection of streptozotocin (STZ; 70 mg/kg body weight) to Sprague-Dawley rats produced type-I diabetic mellitus (fasting blood sugar higher than 300 mg/dL). At 3 and 5 months after STZ or saline injection, retinas from some rats were subjected to cryosectioning for immunofluorescent analysis of SR and TUNEL assay of apoptosis. Retinal homogenates were used to detect SR levels and Jun N-terminal kinase (JNK) activation by immunoblotting. Aqueous humor and retina were also collected to assay for neurotransmitters, including glutamate and D-serine, by reverse-phase HPLC. Results Compared to saline-injected rats, STZ-injected (diabetic) rats showed elevation of SR protein levels in retinal homogenates, attributed to the inner nuclear layer (INL) by immunofluorescence. Aqueous humor fluid from STZ-injected rats contained significantly higher levels of glutamate and D-serine compared to controls; by contrast, D-serine levels in retinas did not differ. Levels of activated JNK were elevated in diabetic retinas compared to controls. Conclusions Increased expression of SR in retina and higher levels of glutamate and D-serine in aqueous humor of STZ-treated rats may result from activation of the JNK pathway in diabetic sequelae. Our data suggest that the inflammatory conditions that prevail during DR result in elevation of D-serine, a neurotransmitter contributing to glutamate toxicity, potentially exacerbating the death of retinal ganglion cells in this condition.

2011-01-01

104

[A serine proteinase from Thermoactinomyces vulgaris, strain INMI-4a].  

PubMed

A serine proteinase was isolated from the cultural filtrate of the thermophylic actinomycet Thermoactinomycet vulgaris, strain INMI-4a. The purification procedure included affinity chromatography on bacitracin-Sepharose, ion-exchange separation on aminosilochrome, and gel-filtration on Sephadex G-25, resulting in a 194-fold purification and the 55% yield of the enzyme. The molecular weight of the enzyme as determined by polyacrylamide gel electrophoresis in the presence of Na-SDS as well as by gel-filtration on Sephadex G-75 is equal to 28 000; the amino acid composition is: Lys11, His4, Arg5, Asp33, Thr22, Ser24, Glu16, Pro16, Gly30, Ala38, Cys1-2, Val20, Met1, Ile14, Leu8, Tyr16, The4, Trp6-7. The isoelectric point lies at pH 8--9; the pH optimum for the peptide substrate hydrolysis is Z-L-Ala-L-Ala-L-Leu-pNA is at 8.2. The enzyme is stable at pH 7--9. The temperature optimum of the proteolytic activity lies at 55 degrees; however, the enzyme is stable to heating for 1 h at 37 degrees. The proteinase is completely inactivated by the serine proteinase specific inhibitors--phenylmethylsulphofluoride and the protein inhibitor IT-AjT from Actinomyces, as well as by p-chloromercuribenzoate. The enzyme shows lytic activity against the cells of E. coli, Micrococcus lysodeicticus and of the yeasts. The Thermoactinomyces vulgaris serine proteinase, being definitely different from the serine proteinases from Actinomyces griseus, also reveals specific differences when compared to bacterial serine proteinases, e. g. subtilisins. There are some indications to the enzyme relationship with the family of carboxypeptidase Y-like serine proteinases. PMID:7016198

Stepanov, V M; Rudenskaia, G N; Nesterova, N G; Kupriianova, T I; Khokhlova, Iu M

1980-10-01

105

Enzymatic methods for the determination of L-serine concentration and L-(/sup 14/C)serine specific radioactivity in blood plasma  

SciTech Connect

Methods are described for the use of L-serine dehydratase purified from Clostridium acidiurici for the determination of L-serine concentrations and L(/sup 14/C)serine specific radioactivity in sheep plasma. A spectrophotometric assay using this enzyme accurately measured the concentration of L-serine in standard solutions and in a commerically available mixture of amino acids and related compounds. This assay was shown to be suitable for measurement of plasma L-serine concentrations in excess of 30 ..mu..M. The reverse isotope dilution method was used for plasma L-(/sup 14/C)serine specific radioactivity measurements. Carrier L-serine was added to plasma and separated from neutral and anionic compounds using ion-exchange chromatography. The L-serine was then converted to pyruvate with L-serine dehydratase and this was purified as the phenylhydrazone derivative. After recrystallization, drying and weighing, the derivative was assayed for radioactivity. The accuracy of this method was verified by adding L-(U-/sup 14/C)serine to plasma and comparing the experimentally determined L-(/sup 14/C)serine specific radioactivity with the calculated value. The method yielded a value which was 98.6 +/- 0.8% of this calculated value.

Cassady, A.I.; Reilly, P.E.B.

1981-11-15

106

Heterogeneous system performance prediction and analysis using PS  

Microsoft Academic Search

PS (PVM simulator), is a simulator of PVM programs which lets users conduct performance prediction and analysis of distributed applications executed in heterogeneous and network computing environments. The article describes the tool and its development environment. As a prediction tool, the PS simulator lets developers obtain extrapolated performance data by estimating the behavior that a parallel application would attain on

Rocco Aversa; Antonino Mazzeo; Nicola Mazzocca; Umberto Villano

1998-01-01

107

Structural and photoluminescence properties of ZnO/PS heterojunction  

NASA Astrophysics Data System (ADS)

Porous silicon templates were formed by electrochemical anodization on p-type (100) silicon wafers and transparent conducting Zinc oxide (ZnO) thin films were deposited on glass substrates and Porous silicon (PS) substrates by sol-gel dip coating technique, using Zinc acetate dehydrate, Monoethanoamine (MEA), ethanol and distilled water. In this process, the films were formed over the surface and also incorporated into the pores of PS and thereby making a shielding layer as well as a contacting workstation. Thus, the ZnO/PS/Si junctions were fabricated. The growth of ZnO on glass and PS has been thoroughly investigated by SEM and X-ray diffraction techniques. The results indicated that ZnO/PS nanocomposite films were polycrystalline in nature with a hexagonal wurtzite structure and the (002) oriented ZnO films had the best crystal quality. The grain size of the films on glass and PS were found to be around 60 nm. Photoluminescence (PL) of the ZnO/PS nanocomposite films were systematically investigated by fluorescence spectrophotometry. The influence on the PS interface was correlated with the luminescent behaviour of the resulting heterojunction structure, which is used for various potential applicarions.

Kulathuraan, Kavu; Natarajan, Balan

2013-02-01

108

Non-peptide inhibitors of HCV serine proteinase.  

PubMed

We screened a chemical library of 2000 compounds for inhibitors of hepatitis C virus (HCV) serine proteinase using an in vitro screening method measuring the hydrolysis of the peptide substrate. Three compounds were found to be the most potent inhibitors (IC50 < 10(-5) M). Two of them had a similar structure, that of halogenated benzanilide, and were not inhibitory for common serine proteinases. They inhibited the enzyme non-competitively with the substrate. Together with the result of the analogous compounds in the chemical library, the presumed structural requirements of the inhibition are pointed out. PMID:9468309

Kakiuchi, N; Komoda, Y; Komoda, K; Takeshita, N; Okada, S; Tani, T; Shimotohno, K

1998-01-16

109

Annihilation of electron-positron pairs in the positronium ion Ps{sup -} and bipositronium Ps{sub 2}  

SciTech Connect

Rates of the two-, three-, four-, and five-photon annihilations of the electron-positron pairs are determined numerically for the three-body positronium ion Ps{sup -}(e{sup -}e{sup +}e{sup -}) and four-body bipositronium ''molecule''Ps{sub 2}(e{sup -}e{sup +}e{sup -}e{sup +}). The values obtained in our computations are {gamma}{sub 2{gamma}}(Ps{sup -}){approx_equal}2.080 485 305 25x10{sup 9} s{sup -1}, {gamma}{sub 3{gamma}}(Ps{sup -}){approx_equal}5.636 415 155 0x10{sup 6} s{sup -1}, {gamma}{sub 4{gamma}}(Ps{sup -}){approx_equal}3.075x10{sup 3} s{sup -1}, {gamma}{sub 5{gamma}}(Ps{sup -}){approx_equal}5.383 s{sup -1}, and {gamma}{sub 2{gamma}}(Ps{sub 2}){approx_equal}4.438 595 2x10{sup 9} s{sup -1}, {gamma}{sub 3{gamma}}(Ps{sub 2}){approx_equal}1.202 497x10{sup 7} s{sup -1}, {gamma}{sub 4{gamma}}(Ps{sub 2}){approx_equal}6.562x10{sup 3} s{sup -1}, {gamma}{sub 5{gamma}}(Ps{sub 2}){approx_equal}11.484 s{sup -1}. The four- and five-photon annihilation rates are significantly smaller than the corresponding two- and three-photon annihilation rates known for these systems. We also determine the rates of one- and zero-photon annihilation for the Ps{sup -} ion and Ps{sub 2} system. The corresponding numerical values are {gamma}{sub 1{gamma}}(Ps{sup -}){approx_equal}3.824 91x10{sup -2} s{sup -1}, {gamma}{sub 1{gamma}}(Ps{sub 2}){approx_equal}1.941 88x10{sup -1} s{sup -1}, and {gamma}{sub 0{gamma}}(Ps{sub 2}){approx_equal}2.321 97x10{sup -9} s{sup -1}.

Frolov, Alexei M. [Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada)

2009-07-15

110

Chiral enrichment of serine via formation, dissociation, and soft-landing of octameric cluster ions  

Microsoft Academic Search

Chiral enrichment of serine is achieved in experiments that involve formation of serine octamers starting from non-racemic\\u000a serine solutions. Serine octamers were generated by means of electrospray and sonic spray ionization of aqueous solutions\\u000a of d\\u000a 3-L-serine (108 Da) and D-serine (105 Da) having different molar ratios of enantiomers. A cyclic process involving the formation\\u000a of chirally-enriched octameric cluster ions

Sergio C. Nanita; Zoltan Takats; R. Graham Cooks; Sunnie Myung; David E. Clemmer

2004-01-01

111

Comparative Immunohistochemical Analysis of Ochratoxin A Tumourigenesis in Rats and Urinary Tract Carcinoma in Humans; Mechanistic Significance of p-S6 Ribosomal Protein Expression  

PubMed Central

Ochratoxin A (OTA) is considered to be a possible human urinary tract carcinogen, based largely on a rat model, but no molecular genetic changes in the rat carcinomas have yet been defined. The phosphorylated-S6 ribosomal protein is a marker indicating activity of the mammalian target of rapamycin, which is a serine/threonine kinase with a key role in protein biosynthesis, cell proliferation, transcription, cellular metabolism and apoptosis, while being functionally deregulated in cancer. To assess p-S6 expression we performed immunohistochemistry on formalin-fixed and paraffin-embedded tumours and normal tissues. Marked intensity of p-S6 expression was observed in highly proliferative regions of rat renal carcinomas and a rare angiosarcoma, all of which were attributed to prolonged exposure to dietary OTA. Only very small OTA-generated renal adenomas were negative for p-S6. Examples of rat subcutaneous fibrosarcoma and testicular seminoma, as well as of normal renal tissue, showed no or very weak positive staining. In contrast to the animal model, human renal cell carcinoma, upper urinary tract transitional cell carcinoma from cases of Balkan endemic nephropathy, and a human angiosarcoma were negative for p-S6. The combined findings are reminiscent of constitutive changes in the rat tuberous sclerosis gene complex in the Eker strain correlated with renal neoplasms, Therefore rat renal carcinogenesis caused by OTA does not obviously mimic human urinary tract tumourigenesis.

Gazinska, Patrycja; Herman, Diana; Gillett, Cheryl; Pinder, Sarah; Mantle, Peter

2012-01-01

112

Telomere Reprogramming and Maintenance in Porcine iPS Cells.  

PubMed

Telomere reprogramming and silencing of exogenous genes have been demonstrated in mouse and human induced pluripotent stem cells (iPS cells). Pigs have the potential to provide xenotransplant for humans, and to model and test human diseases. We investigated the telomere length and maintenance in porcine iPS cells generated and cultured under various conditions. Telomere lengths vary among different porcine iPS cell lines, some with telomere elongation and maintenance, and others telomere shortening. Porcine iPS cells with sufficient telomere length maintenance show the ability to differentiate in vivo by teratoma formation test. IPS cells with short or dysfunctional telomeres exhibit reduced ability to form teratomas. Moreover, insufficient telomerase and incomplete telomere reprogramming and/or maintenance link to sustained activation of exogenous genes in porcine iPS cells. In contrast, porcine iPS cells with reduced expression of exogenous genes or partial exogene silencing exhibit insufficient activation of endogenous pluripotent genes and telomerase genes, accompanied by telomere shortening with increasing passages. Moreover, telomere doublets, telomere sister chromatid exchanges and t-circles that presumably are involved in telomere lengthening by recombination also are found in porcine iPS cells. These data suggest that both telomerase-dependent and telomerase-independent mechanisms are involved in telomere reprogramming during induction and passages of porcine iPS cells, but these are insufficient, resulting in increased telomere damage and shortening, and chromosomal instability. Active exogenes might compensate for insufficient activation of endogenous genes and incomplete telomere reprogramming and maintenance of porcine iPS cells. Further understanding of telomere reprogramming and maintenance may help improve the quality of porcine iPS cells. PMID:24098638

Ji, Guangzhen; Ruan, Weimin; Liu, Kai; Wang, Fang; Sakellariou, Despoina; Chen, Jijun; Yang, Yang; Okuka, Maja; Han, Jianyong; Liu, Zhonghua; Lai, Liangxue; Gagos, Sarantis; Xiao, Lei; Deng, Hongkui; Li, Ning; Liu, Lin

2013-09-30

113

Telomere Reprogramming and Maintenance in Porcine iPS Cells  

PubMed Central

Telomere reprogramming and silencing of exogenous genes have been demonstrated in mouse and human induced pluripotent stem cells (iPS cells). Pigs have the potential to provide xenotransplant for humans, and to model and test human diseases. We investigated the telomere length and maintenance in porcine iPS cells generated and cultured under various conditions. Telomere lengths vary among different porcine iPS cell lines, some with telomere elongation and maintenance, and others telomere shortening. Porcine iPS cells with sufficient telomere length maintenance show the ability to differentiate in vivo by teratoma formation test. IPS cells with short or dysfunctional telomeres exhibit reduced ability to form teratomas. Moreover, insufficient telomerase and incomplete telomere reprogramming and/or maintenance link to sustained activation of exogenous genes in porcine iPS cells. In contrast, porcine iPS cells with reduced expression of exogenous genes or partial exogene silencing exhibit insufficient activation of endogenous pluripotent genes and telomerase genes, accompanied by telomere shortening with increasing passages. Moreover, telomere doublets, telomere sister chromatid exchanges and t-circles that presumably are involved in telomere lengthening by recombination also are found in porcine iPS cells. These data suggest that both telomerase-dependent and telomerase-independent mechanisms are involved in telomere reprogramming during induction and passages of porcine iPS cells, but these are insufficient, resulting in increased telomere damage and shortening, and chromosomal instability. Active exogenes might compensate for insufficient activation of endogenous genes and incomplete telomere reprogramming and maintenance of porcine iPS cells. Further understanding of telomere reprogramming and maintenance may help improve the quality of porcine iPS cells.

Ji, Guangzhen; Ruan, Weimin; Liu, Kai; Wang, Fang; Sakellariou, Despoina; Chen, Jijun; Yang, Yang; Okuka, Maja; Han, Jianyong; Liu, Zhonghua; Lai, Liangxue; Gagos, Sarantis; Xiao, Lei; Deng, Hongkui; Li, Ning; Liu, Lin

2013-01-01

114

Uitbreiding van Het Timing-Sytseem Tbv. AmPs (Extension of the Timing System for AmPs).  

National Technical Information Service (NTIS)

The timing system of the kickers and RF system in the Amsterdam Pulse Stretcher (AmPS) storage ring were improved. The extension of AmPS requires a very precise timing of the RF station and the kicker system. The easiest realization was found to be a para...

E. Heine J. Kuijt

1991-01-01

115

Dynamics simulation of the interaction between serine and water.  

PubMed

Using the first principles density functional theory (DFT), we simulated the neutron scattering spectra of the hydration dynamics of serine. Experimental data analyses have shown that dissociative H2O molecules were more likely to form hydrogen bonds (H-bonds) with an -OH group in monohydrated serine and easily shift to a -NH3 (+) group at a higher hydration level [P. Zhang, Y. Zhang, S. H. Han, Q. W. Yan, R. C. Ford, and J. C. Li, J. Phys. Chem. A 110, 5000 (2006)]. We set the 1:1 ratio hydrated compounds at the two positions and found that the H2O could be optimized to form H-bonds with -OH and -NH3 (+) separately. When the simulated phonon signals of the -OH···H2O and -NH3(+)···H2O combinations were summed on a 3:1 scale, the calculating spectra were in good agreement with the experimental results, especially for the peak at 423 cm(-1) of the -OH···H2O combination and the peak at 367 cm(-1) of the -NH3(+)···H2O combination, which mutually complemented the real spectrum. We confirm that H2O may break the intermolecular H-bonds of the interlaced binding -OH to form a new structure, and that with the skeleton deformation of serine, H2O forms stronger H-bonds more often with the -NH3 (+) side indicating the flexible dynamic mechanism of the serine hydration process. PMID:23742519

Liu, Yang; Zhang, Peng; Lu, Ying-Bo; Han, Sheng-Hao; Yu, Hui

2013-05-28

116

Identification of Serine Proteinases Involved in Breast Cancer Progression.  

National Technical Information Service (NTIS)

The objective of the grant was to identify serine proteinases (a) upregulated in malignant breast epithelial T4-2 cells, and (b) for which specific inhibition by RNA interference (RNAi) results in suppression of the malignant phenotype, as assessed in thr...

E. Radisky

2007-01-01

117

Affinity purification of serine proteinase from Deinagkistrodon acutus venom.  

PubMed

An affinity protocol was developed for the preparation of the main serine proteinase from Deinagkistrodon acutus venom on industrial scales. As affinity ligand, l-arginine was composed to medium and its structure was confirmed by ESI-MS analysis. The purification process consisted of one major affinity chromatography step to remove more than 95% of other proteins, and a polishing step of DEAE ion-exchange chromatography for removal of minor contaminants. The serine proteinase was 100% pure analyzed on HPLC Vydac C4 column, 99.4% on TSK G3000SW column, and 97.7% with SDS-PAGE analysis. The yield of the main serine proteinase was 3.6% of crude venom protein, the recoveries of typical fibrinogen (Fg) clotting activity and arginine esterase activity of serine proteinase were 82.2% and 84%, higher than those of other reported traditional protocols, the proteinase also showed arginine amidase activity. Reducing SDS-PAGE analysis showed that the arginine esterase was a single polypeptide with the mass of approximately 40 kDa, while MALDI-TOF-TOF-MS analysis showed that the purified proteinase should be a approximately 34 kDa glycoprotein. The desorption constant Kd and the theoretical maximum absorption Qmax on the affinity medium were 9.93 x 10(-5) and 38.1mg/g medium in absorption analysis. PMID:17904430

Xin, Yu; Dong, Dexian; Wang, Ting; Li, Rongxiu

2007-09-14

118

Stimulation of A2a adenosine receptor abolishes the inhibitory effect of arachidonic acid on the basolateral 50-pS K channel in the thick ascending limb  

PubMed Central

The basolateral 50-pS K channels are stimulated by a cAMP-dependent pathway and inhibited by cytochrome P-450-omega-hydroxylase-dependent metabolism of arachidonic acid (AA) in the rat thick ascending limb (TAL). We now used the patch-clamp technique to examine whether stimulation of adenosine A2a receptor modulates the inhibitory effect of AA on the basolateral 50-pS K channels in the medullary TAL. Stimulation of adenosine A2a receptor with CGS-21680 or inhibition of phospholipase A2 (PLA2) with AACOCF3 increased the 50-pS K channel activity in the TAL. Western blot demonstrated that application of CGS-21680 decreased the phosphorylation of PLA2 at serine residue 505, an indication of inhibiting PLA2 activity. In the presence of CGS-21680, inhibition of PLA2 had no further effect on the basolateral 50-pS K channels. The possibility that CGS-21680-induced stimulation of the basolateral 50-pS K channels was partially achieved by inhibition of PLA2 in the TAL was also supported by the observation that CGS-21680 had no additional effect in the presence of AACOCF3. Moreover, stimulation of adenosine A2a receptor with CGS-21680 also abolished the inhibitory effect of AA and 20-hydroxyeicosatetraenoic acid (20-HETE) on the 50-pS K channels. The effect of CGS-21680 on AA and 20-HETE-mediated inhibition of the 50-pS K channels was mediated by cAMP because application of membrane-permeable cAMP analog, dibutyryl-cAMP, not only increased the 50-pS K channel activity but also abolished the inhibitory effect of AA and 20-HETE. We conclude that stimulation of adenosine A2a receptor increased the 50-pS K channel activity in the TAL, an effect that is achieved by suppression of PLA2 activity and 20-HETE-induced inhibition.

Wang, Mingxiao; Sui, Hongyu; Li, Wennan; Wang, Jing; Liu, Yujie; Gu, Li; Wang, Wen-Hui

2011-01-01

119

Sphingoid bases and the serine catabolic enzyme CHA1 define a novel feedforward/feedback mechanism in the response to serine availability.  

PubMed

Targets of bioactive sphingolipids in Saccharomyces cerevisiae were previously identified using microarray experiments focused on sphingolipid-dependent responses to heat stress. One of these heat-induced genes is the serine deamidase/dehydratase Cha1 known to be regulated by increased serine availability. This study investigated the hypothesis that sphingolipids may mediate the induction of Cha1 in response to serine availability. The results showed that inhibition of de novo synthesis of sphingolipids, pharmacologically or genetically, prevented the induction of Cha1 in response to increased serine availability. Additional studies implicated the sphingoid bases phytosphingosine and dihydrosphingosine as the likely mediators of Cha1 up-regulation. The yeast protein kinases Pkh1 and Pkh2, known sphingoid base effectors, were found to mediate CHA1 up-regulation via the transcription factor Cha4. Because the results disclosed a role for sphingolipids in negative feedback regulation of serine metabolism, we investigated the effects of disrupting this mechanism on sphingolipid levels and on cell growth. Intriguingly, exposure of the cha1? strain to high serine resulted in hyperaccumulation of endogenous serine and in turn a significant accumulation of sphingoid bases and ceramides. Under these conditions, the cha1? strain displayed a significant growth defect that was sphingolipid-dependent. Together, this work reveals a feedforward/feedback loop whereby the sphingoid bases serve as sensors of serine availability and mediate up-regulation of Cha1 in response to serine availability, which in turn regulates sphingolipid levels by limiting serine accumulation. PMID:22277656

Montefusco, David J; Newcomb, Benjamin; Gandy, Jason L; Brice, Sarah E; Matmati, Nabil; Cowart, L Ashley; Hannun, Yusuf A

2012-01-25

120

Polyphyllin D is a potent apoptosis inducer in drug-resistant HepG2 cells  

Microsoft Academic Search

In a search for new anticancer agents, we identified a novel compound polyphyllin D (PD) (diosgenyl ?-l-rhamnopyranosyl-(1?2)-(?-l-arabinofuranosyl)-(1?4)]-[?-d-glucopyranoside) that induced DNA fragmentation and phosphatidyl-serine (PS) externalization in a hepatocellular carcinoma cell line HepG2 derivative with drug resistance (R-HepG2). PD is a saponin originally found in a tradition Chinese medicinal herb Paris polyphylla. It has been used to treat liver cancer in

Jenny Yuen-Nei Cheung; Rose Chik-Ying Ong; Yick-Keung Suen; Vincent Ooi; Henry Nai-Ching Wong; Thomas Chung-Wai Mak; Kwok-Pui Fung; Biao Yu; Siu-Kai Kong

2005-01-01

121

PP and PS interferometric images of near-seafloor sediments  

USGS Publications Warehouse

I present interferometric processing examples from an ocean-bottom cable OBC dataset collected at a water depth of 800 m in the Gulf of Mexico. Virtual source and receiver gathers created through cross-correlation of full wavefields show clear PP reflections and PS conversions from near-seafloor layers of interest. Virtual gathers from wavefield-separated data show improved PP and PS arrivals. PP and PS brute stacks from the wavefield-separated data compare favorably with images from a non-interferometric processing flow. ?? 2011 Society of Exploration Geophysicists.

Haines, S. S.

2011-01-01

122

First photometric study of the eclipsing binary PS Persei  

NASA Astrophysics Data System (ADS)

CCD photometric observations of the eclipsing binary PS Persei (PS Per) were obtained on two consecutive days in 2009. The 2003 version of the Wilson-Devinney code was used to analyze the first complete light curves in the V and R bands. It is found that PS Per is a short-period Algol-type binary with the less massive component completely filling its inner critical Roche lobe. The mass ratio of q = 0.518 and the orbital inclination of i = 89.86° are obtained. In addition, based on all available times of primary light minima, including two new ones, the orbital period has been improved.

Yuan, Jin-Zhao

2011-02-01

123

Stat1 Serine Phosphorylation Occurs Independently of Tyrosine Phosphorylation and Requires an Activated Jak2 Kinase  

Microsoft Academic Search

Gamma interferon (IFN-g) induces both tyrosine and serine phosphorylation of Stat1. Stat1 serine phos- phorylation is required for maximal transcriptional activity of Stat1. In this report, we present evidence that Stat1 tyrosine phosphorylation is not a prerequisite for Stat1 serine phosphorylation, although an active Jak2 kinase is required for both phosphorylation events. Stat1 serine phosphorylation occurs with a more delayed

XUEJUN ZHU; ZILONG WEN; LIANG ZHONG XU; JAMES E. DARNELL

1997-01-01

124

Proton flow through the ATP synthase in chloroplasts regulates the distribution of light energy between PS I and PS II.  

PubMed

The involvement of ATP synthase in the imbalance between the photoactivities of PS I and PS II under light-limiting conditions, was examined in broken lettuce chloroplasts using modulated fluorimetry. The imbalance, in favor of PS II, was minimal and roughly constant between pH 6.5-7.3 (ratio of PS II/PS I activities about 1.1), and maximal at pH 8.5 (ratio of PS II/PS I activities about 1.4). This increase was strongly inhibited by a treatment of the chloroplasts with the CF0 ATP synthase inhibitor DCCD, but unaffected by the CF1 ATPase inhibitor, tentoxin. However, tentoxin plus ADP-P1 did inhibit the high pH-induced increased imbalance. These results, when considered with the previous results on the effect of high pH on proton flux through the ATP synthase, suggest that the rate of such proton flow controls the imbalance between the two photo-systems. It is possible that there is an in vivo fine-tuning regulating mechanism of the photosystems imbalance via the opening and closing of proton gradient dissipation through the ATP synthase. This mechanism may help alleviate photoinhibitory damage. PMID:1849095

Braun, G; Evron, Y; Malkin, S; Avron, M

1991-03-11

125

A Novel Serine Protease Inhibitor Acts as an Immunomodulatory Switch while Maintaining Homeostasis  

Microsoft Academic Search

Serine protease cascades boost immune responses while maintaining homeostasis. These crucial actions are intricately regulated by cognate serine protease inhibitors. However, the mechanism underlying such a dynamic immunomodulation during acute phase infection remains obscure, particularly where the pathogen’s serine protease adds a new challenge to the host. Here, we found that infection of horseshoe crab, Carcinoscorpius rotundicauda, induced reciprocal profiles

N. Jiang; S. Thangamani; C. F. Chor; S. Y. Wang; I. Winarsih; R. J. Du; J. Sivaraman; B. Ho; J. L. Ding

2009-01-01

126

Synergistic Computational and Experimental Proteomics Approaches for More Accurate Detection of Active Serine Hydrolases in Yeast  

Microsoft Academic Search

An analysis of the structurally and catalytically diverse serine hydrolase protein family in the Saccharomyces cer- evisiae proteome was undertaken using two independent but complementary, large-scale approaches. The first ap- proach is based on computational analysis of serine hy- drolase active site structures; the second utilizes the chemical reactivity of the serine hydrolase active site in complex mixtures. These proteomics

Susan M. Baxter; Jonathan S. Rosenblum; Stacy Knutson; Melanie R. Nelson; Jennifer S. Montimurro; Jeannine A. Di Gennaro; Jeffrey A. Speir; Jonathan J. Burbaum; Jacquelyn S. Fetrow

2004-01-01

127

Identification and structural analysis of four serine proteases in a monotreme, the platypus, Ornithorhynchus anatinus  

Microsoft Academic Search

To study the emergence of the major subfamilies of serine proteases during vertebrate evolution, we present here the primary structure of four serine proteases expressed in the spleen of a monotreme, the platypus, Ornithorhynchus anatinus. Partial cDNA clones for four serine proteases were isolated by a PCR-based strategy. This strategy is based on the high level of sequence identity between

Maryam Poorafshar; Maria Aveskogh; Barry Munday; Lars Hellman

2000-01-01

128

Serine proteases of the human immune system in health and disease  

Microsoft Academic Search

Serine proteases form a large family of protein-cleaving enzymes that play an essential role in processes like blood coagulation, apoptosis and inflammation. Immune cells express a wide variety of serine proteases such as granzymes in cytotoxic lymphocytes, neutrophil elastase, cathepsin G and proteinase 3 in neutrophils and chymase and tryptase in mast cells. Regulation of proteolysis induced by these serine

Kirstin M. Heutinck; Ineke J. M. ten Berge; C. Erik Hack; Jörg Hamann; Ajda T. Rowshani

2010-01-01

129

Modeling and structural analysis of PA clan serine proteases  

PubMed Central

Background Serine proteases account for over a third of all known proteolytic enzymes; they are involved in a variety of physiological processes and are classified into clans sharing structural homology. The PA clan of endopeptidases is the most abundant and over two thirds of this clan is comprised of the S1 family of serine proteases, which bear the archetypal trypsin fold and have a catalytic triad in the order Histidine, Aspartate, Serine. These proteases have been studied in depth and many three dimensional structures have been experimentally determined. However, these structures mostly consist of bacterial and animal proteases, with a small number of plant and fungal proteases and as yet no structures have been determined for protozoa or archaea. The core structure and active site geometry of these proteases is of interest for many applications. This study investigated the structural properties of different S1 family serine proteases from a diverse range of taxa using molecular modeling techniques. Results Our predicted models from protozoa, archaea, fungi and plants were combined with the experimentally determined structures of 16 S1 family members and used for analysis of the catalytic core. Amino acid sequences were submitted to SWISS-MODEL for homology-based structure prediction or the LOOPP server for threading-based structure prediction. Predicted models were refined using INSIGHT II and SCRWL and validated against experimental structures. Investigation of secondary structures and electrostatic surface potential was performed using MOLMOL. The structural geometry of the catalytic core shows clear deviations between taxa, but the relative positions of the catalytic triad residues were conserved. Some highly conserved residues potentially contributing to the stability of the structural core were identified. Evolutionary divergence was also exhibited by large variation in secondary structure features outside the core, differences in overall amino acid distribution, and unique surface electrostatic potential patterns between species. Conclusions Encompassing a wide range of taxa, our structural analysis provides an evolutionary perspective on S1 family serine proteases. Focusing on the common core containing the catalytic site of the enzyme, this analysis is beneficial for future molecular modeling strategies and structural analysis of serine protease models.

2012-01-01

130

Isolation options for non-cellulosic heteropolysaccharides (HetPS)  

Microsoft Academic Search

The isolation of non-cellulosic heteropolysaccharides (HetPS) from barley husks (Hordeum spp.) and yellow poplar wood chips (Liriodendron tulipifera) was accomplished using mild steam explosion followed by extraction with water and ultrafiltration. The generally low yields, low purity, and low degree of polymerization (DP) improved when the HetPS were isolated following either alkali extraction of hammermilled or disk-refined biomass, or from

Wolfgang G. Glasser; William E. Kaar; Rajesh K. Jain; James E. Sealey

2000-01-01

131

The PS1 Science Mission - Status and Results  

NASA Astrophysics Data System (ADS)

PS1, the Pan-STARRS1 Telescope is in its last year of the PS1 Science Mission. Operations of the PS1 System include the Observatory, Telescope, 1.4 Gigapixel Camera, Image Processing Pipeline , PSPS relational database and reduced science product software servers. The PS1 Surveys include: (1) A 3pi Steradian Survey, (2) A Medium Deep survey of 10 PS1 footprints spaced around the sky; (3) A solar system survey optimized for Near Earth Objects, (4) a Stellar Transit Survey; and (5) a Deep Survey of M31. The PS1 3pi Survey has now covered the sky north of dec=-30 with 8 to 12 visits in five bands: g,r,i,z and y or over ~45 epochs per point on sky. The performance of the PS1 system, sky coverage, cadence, and data quality of the surveys will be presented as well as progress in reprocessing of the data taken to date and plans for serving the data to the public. A summary of science highlights will be included. The PS1 Science Consortium consists of The Institute for Astronomy at the University of Hawai'i in Manoa, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, the University of Durham, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Los Cumbres Observatory Global Telescope Network Incorporated, and the National Central University of Taiwan, NASA, and NSF.

Chambers, Kenneth C.

2013-06-01

132

PS-PVD Process for Coating Aircraft Engine Components  

NASA Video Gallery

This short video shows a process that NASA's Glenn Research Center is developing that can deposit very thin and smooth layers of coating on ceramic matrix composite materials for use as aircraft engine turbine components. The process, called "Plasma Spray-Physical Vapor Deposition," or PS-PVD, can apply coatings that withstand up to 2700 degrees Fahrenheit, improving engine thermal efficiency and reducing fuel burn. › Watch 'Intro to PS-PVD Process'

Christopher O

2013-03-06

133

Considerations in 3D depth-specific PS survey design  

Microsoft Academic Search

A new sparse-shot design for 3D P-S surveys is introduced. In the sparse shot design a shot separation greater than the receiver separation is used, and given by the relationship ?s = ?r(1 + Vp\\/Vs)\\/2. This design yields fewer non-unique P-S traces than traditional 3D surveys with equal source and receiver intervals. New measures of global offset and azimuth distribution

Don C. Lawton; Peter W. Cary

2003-01-01

134

Electron cloud effects for PS2, SPS(+) and LHC  

Microsoft Academic Search

Electron cloud effects are expected to be enhanced and play a central role in limiting the performance of the ma- chines of the CERN complex after the upgrade that is planned to take place in the next years. The beam will be injected into the SPS through the chain Linac4-SPL-PS2, replacing the existing Linac2-PSB-PS. The ultimate LHC beam in the

G. Rumolo

135

iPS cells: a more critical review.  

PubMed

Over the past 20 months, reports claiming the generation of induced pluripotent stem (iPS) cells with characteristics identical to those of embryonic stem (ES) cells from nonembryonic tissue have captured great attention in both the scientific community and the general public. In the light of the continuing controversy over the use of ES cells, these reports have profound ramifications. This review calls into question the validity of many claims made in these reports--claims that have led to the rapid and premature acceptance of using iPS cells as a viable alternative to using normal stem cells for regenerative therapy. How convincing is the evidence supporting the various claims made for the iPS cells? Are there other more plausible explanations for the same observations? What are these iPS cells? Are they really safe for therapeutic use? Should the iPS technique be considered, in the absence of any direct evidence for induction and reprogramming, as a realistic alternative for somatic cell nuclear transfer (SCNT) to generate ES-like cells? This review attempts to encourage reflections on and offer alternative views for key aspects of iPS cells and studies. PMID:18426340

Liu, Shi V

2008-06-01

136

The importance of serine proteinases as aeroallergens associated with asthma.  

PubMed

Penicillium and Aspergillus species have been identified as prevalent indoor airborne fungi that are associated with extrinsic bronchial asthma. We have recently analyzed the IgE-binding components in 8 prevalent Penicillium and Aspergillus species (P. citrinum, P. notatum, P. oxalicum, P. brevicompactum, A. fumigatus, A. flavus, A. oryzae and A. niger) by immunoblotting and N-terminal amino acid sequence analysis. Our results show that the alkaline and/or vacuolar serine proteinases are the major allergens in these prevalent fungal species. IgE cross-reactivity among these major allergens was also detected. Results obtained provide an important basis for clinical allergy. In addition, monoclonal antibodies against alkaline and/or vacuolar serine proteinase allergens have been generated. These antibodies can be applied for the standardization of allergenic extracts. PMID:10474030

Shen, H D; Tam, M F; Chou, H; Han, S H

1999-08-01

137

Calcium-induced inactivation of alamethicin in asymmetric lipid bilayers  

PubMed Central

This paper discusses a calcium-dependent inactivation of alamethicin- induced conductance in asymmetric lipid bilayers. The bilayers used were formed with one leaflet of phosphatidyl ethanolamine (PE) and one of phosphatidyl serine (PS). Calcium, initially confined to the neutral lipid (PE) side, can pass through the open alamethicin channel to the negative lipid (PS) side, where it can bind to the negative lipid and reduce the surface potential. Under appropriate circumstances, the voltage-dependent alamethicin conductance is thereby inactivated. We have formulated a model for this process based on the diffusion of calcium in the aqueous phases and we show that the model describes the kinetic properties of the alamethicin conductance under various circumstances. EGTA on the PS side of the membrane reduces the effects of calcium dramatically as predicted by the model.

1982-01-01

138

Dissecting the catalytic triad of a serine protease  

Microsoft Academic Search

Serine proteases are present in virtually all organisms and function both inside and outside the cell1; they exist as two families, the 'trypsin-like' and the 'subtilisin-like', that have independently evolved a similar catalytic device2 characterized by the Ser, His, Asp triad, an oxyanion binding site, and possibly other determinants that stabilize the transition state (Fig. l) 2-4. For Bacillus amyloliquefaciens

Paul Carter; James A. Wells

1988-01-01

139

Characterization of serine proteases in the monogenean Neobenedenia girellae  

Microsoft Academic Search

Proteases of Neobenedenia girellae were examined by using zymographic analysis. Zymography of N. girellae homogenate revealed proteases at approximately 88, 107, 149 and 167kDa for the adult worms and approximately 147 and 166kDa for the oncomiracidia, respectively. The enzyme activities were inhibited by Pefabloc SC but were not inhibited by E-64 and Pepstatin A, indicating that these proteases were serine

Noritaka Hirazawa; Naoko Umeda; Akimasa Hatanaka; Akashi Kuroda

2006-01-01

140

Quantum chemical study of simple positronic systems using explicitly correlated Gaussian functions - PsH and PsLi+  

NASA Astrophysics Data System (ADS)

The electronic structure of positronium hydride has been studied using explicitly correlated Gaussian functions. The resulting energy constitutes new upper bound to the exact nonrelativistic energy of PsH within the Born-Oppenheimer approximation. The two photon annihilation rate was computed using the optimized wave function. Preliminary results for the positron bonded with the lithium atom indicate the stability of this system against the dissociation into Li+ cation and Ps atom.

Strasburger, K.; Chojnacki, H.

1998-02-01

141

Arabidopsis serine decarboxylase mutants implicate the roles of ethanolamine in plant growth and development.  

PubMed

Ethanolamine is important for synthesis of choline, phosphatidylethanolamine (PE) and phosphatidylcholine (PC) in plants. The latter two phospholipids are the major phospholipids in eukaryotic membranes. In plants, ethanolamine is mainly synthesized directly from serine by serine decarboxylase. Serine decarboxylase is unique to plants and was previously shown to have highly specific activity to l-serine. While serine decarboxylase was biochemically characterized, its functions and importance in plants were not biologically elucidated due to the lack of serine decarboxylase mutants. Here we characterized an Arabidopsis mutant defective in serine decarboxylase, named atsdc-1 (Arabidopsis thaliana serine decarboxylase-1). The atsdc-1 mutants showed necrotic lesions in leaves, multiple inflorescences, sterility in flower, and early flowering in short day conditions. These defects were rescued by ethanolamine application to atsdc-1, suggesting the roles of ethanolamine as well as serine decarboxylase in plant development. In addition, molecular analysis of serine decarboxylase suggests that Arabidopsis serine decarboxylase is cytosol-localized and expressed in all tissue. PMID:22489147

Kwon, Yerim; Yu, Si-In; Lee, Hyoungseok; Yim, Joung Han; Zhu, Jian-Kang; Lee, Byeong-Ha

2012-03-07

142

The Raf-1 serine/threonine protein kinase.  

PubMed

Raf-1 belongs to a family of serine/threonine protein kinases which are highly conserved through evolution in multicellular organisms. Raf-1 kinase has gained much attention due to its function as a critical shuttle enzyme that connects stimulation of growth factor receptors and protein kinase C at the cell membrane to changes in the expression of genes involved in the control of cell growth, differentiation and survival. Regulation of Raf-1 activity is complex and involves Ras, as well as several serine/threonine and tyrosine kinases. Through a series of phosphorylation events, extracellular signals are connected through the Raf-1/MAP kinase pathway to activity-regulation of several oncogene-class transcription factors via phosphorylation of specific serine residues. Under ordinary circumstances, the cascade involving Raf-1 eventually leads to changes in gene expression and protein synthesis. Upon constitutive activation of Raf-1 kinase, as a result of genetic changes, a variety of cell types acquire a transformed phenotype. PMID:7803760

Magnuson, N S; Beck, T; Vahidi, H; Hahn, H; Smola, U; Rapp, U R

1994-08-01

143

Structural Basis for Catalytic Activation of a Serine Recombinase  

SciTech Connect

Sin resolvase is a site-specific serine recombinase that is normally controlled by a complex regulatory mechanism. A single mutation, Q115R, allows the enzyme to bypass the entire regulatory apparatus, such that no accessory proteins or DNA sites are required. Here, we present a 1.86 {angstrom} crystal structure of the Sin Q115R catalytic domain, in a tetrameric arrangement stabilized by an interaction between Arg115 residues on neighboring subunits. The subunits have undergone significant conformational changes from the inactive dimeric state previously reported. The structure provides a new high-resolution view of a serine recombinase active site that is apparently fully assembled, suggesting roles for the conserved active site residues. The structure also suggests how the dimer-tetramer transition is coupled to assembly of the active site. The tetramer is captured in a different rotational substate than that seen in previous hyperactive serine recombinase structures, and unbroken crossover site DNA can be readily modeled into its active sites.

Keenholtz, Ross A.; Rowland, Sally-J.; Boocock, Martin R.; Stark, W. Marshall; Rice, Phoebe A. (Glasgow); (UC)

2011-12-07

144

Defining Substrate and Blocker Activity of Alanine-Serine-Cysteine Transporter 2 (ASCT2) Ligands with Novel Serine Analogs  

PubMed Central

The neutral amino acid transporter alanine-serine-cysteine transporter 2 (ASCT2) belongs to the solute carrier 1 (SLC1) family of solute transporters and transports small, neutral amino acids across the membrane, including the physiologically important and ubiquitous amino acid glutamine. Our understanding of the involvement of ASCT2 in the physiological processes involving glutamine is hampered by a lack of understanding of its pharmacology and the absence of high-affinity inhibitors. In this study, we combined an in silico docking approach with experimental investigation of binding parameters to develop new ASCT2 inhibitors and substrates, a series of serine esters, and to determine structural parameters that govern their functional effects. The series of compounds was synthesized using standard methods and exhibited a range of properties, from inhibitors to partial substrates and full substrates. Our results suggest that amino acid derivatives with small side-chain volume and low side-chain hydrophobicity interact strongly with the closed-loop form of the binding site, in which re-entrant loop 2, the presumed extracellular gate for the substrate binding site, is closed off. However, these derivatives bind weakly to the open-loop form (external gate open to the extracellular side), acting as transported substrates. In contrast, inhibitors bind preferentially to the open-loop form. An aromatic residue in the side chain is required for high-affinity interaction. One of the compounds, the l-serine ester serine biphenyl-4-carboxylate reversibly inhibits ASCT2 function with an apparent affinity of 30 ?M.

Albers, Thomas; Marsiglia, William; Thomas, Taniya; Gameiro, Armanda

2012-01-01

145

Induced pluripotent stem (iPS) cell research overview.  

PubMed

Stem cells are capable of self-renewal and differentiation into a wide range of cell types with multiple clinical therapeutic applications. The two most important issues associated with embryonic stem (ES) cells are immune rejection and medical ethics. In 2006, induced pluripotent (iPS) cells were generated from somatic cells via the introduction of four transcriptional factors: OCT4, SOX2, c-MYC, and KLF4. Researchers found that iPS cell morphology, proliferation, surface antigens, gene expression, telomerase activity, and the epigenetic status of pluripotent cell-specific genes were similar to the same characteristics in ES cells. iPS cells are capable of overcoming hurdles associated with ES cells due to their generation from mature somatic cells (e.g., fibroblasts). For this reason, iPS cells are considered an increasingly important cell therapy technology. iPS cell production entails the use of retroviruses, lentiviruses, adenoviruses, plasmid transfections, transposons, or recombinant proteins. In this article we discuss the advantages and limitations of each strategy and address issues associated with clinical trials, including the potential for liver tumor formation and low generation efficiency. PMID:20887681

Liu, Shih-Ping; Fu, Ru-Huei; Huang, Yu-Chuen; Chen, Shih-Yin; Chien, Ying-Jiun; Hsu, Chien Yu; Tsai, Chang-Hai; Shyu, Woei-Cherng; Lin, Shinn-Zong

2010-09-30

146

Storage and uptake of d-serine into astrocytic synaptic-like vesicles specify gliotransmission  

PubMed Central

Glial cells are increasingly recognized as active players that profoundly influence neuronal synaptic transmission by specialized signalling pathways. In particular, astrocytes have recently been shown to release small molecules such as the amino acids l-glutamate and d-serine as “gliotransmitters”, which directly control the efficacy of adjacent synapses. However, it is still controversial whether gliotransmitters are released from a cytosolic pool or by Ca2+-dependent exocytosis from secretory vesicles, i.e., by a mechanism similar to the release of synaptic vesicles in synapses. Here we report that rat cortical astrocytes contain storage vesicles that display morphological and biochemical features similar to neuronal synaptic vesicles. These vesicles share some, but not all, membrane proteins with synaptic vesicles including the SNARE synaptobrevin 2 and contain both l-glutamate and d-serine. Furthermore, they show uptake of l-glutamate and d-serine that is driven by a proton electrochemical gradient. d-Serine uptake is associated with vesicle acidification and is dependent on chloride. While l-serine is not transported, serine racemase, the synthesizing enzyme for d-serine, is anchored to the membrane of the vesicles allowing local generation of d-serine. Finally, we reveal a previously unexpected mutual vesicular synergy between d-serine and l-glutamate filling in glia vesicles. We conclude that astrocytes contain vesicles capable of storing and releasing d-serine, l-glutamate, and most likely other neuromodulators in an activity-dependent manner.

Martineau, Magalie; Shi, Ting; Puyal, Julien; Knolhoff, Ann M.; Dulong, Jerome; Gasnier, Bruno; Klingauf, Jurgen; Sweedler, Jonathan V.; Jahn, Reinhard; Mothet, Jean-Pierre

2013-01-01

147

D-serine, an endogenous synaptic modulator: localization to astrocytes and glutamate-stimulated release.  

PubMed Central

Using an antibody highly specific for D-serine conjugated to glutaraldehyde, we have localized endogenous D-serine in rat brain. Highest levels of D-serine immunoreactivity occur in the gray matter of the cerebral cortex, hippocampus, anterior olfactory nucleus, olfactory tubercle, and amygdala. Localizations of D-serine immunoreactivity correlate closely with those of D-serine binding to the glycine modulatory site of the N-methyl-D-aspartate (NMDA) receptor as visualized by autoradiography and are inversely correlated to the presence of D-amino acid oxidase. D-Serine is enriched in process-bearing glial cells in neuropil with the morphology of protoplasmic astrocytes. In glial cultures of rat cerebral cortex, D-serine is enriched in type 2 astrocytes. The release of D-serine from these cultures is stimulated by agonists of non-NMDA glutamate receptors, suggesting a mechanism by which astrocyte-derived D-serine could modulate neurotransmission. D-Serine appears to be the endogenous ligand for the glycine site of NMDA receptors. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4

Schell, M J; Molliver, M E; Snyder, S H

1995-01-01

148

Characterization of MeV proton irradiated PS films  

NASA Astrophysics Data System (ADS)

Poly(styrene) PS thin films were irradiated under vacuum with protons of three different energies and fluences. Radiation can induce polycyclic structures formation, as could be observed by UV and NMR. To support these observations, H-NMR and C, H concentration measurements were performed. The film becomes more rigid due to the possible formation of cyclic chemical groups and crosslinking. PS is known for its great stability to ionizing radiation and other degradation processes. Indeed, we studied the mass loss during bombardment, measuring the C and H concentration by proton scattering (back and forward). With dose up to 510 MGy, no mass loss was observed. Based on the results obtained in this study, a free radicals mechanism for PS is suggested, with the goal to explain the modifications induced by MeV proton irradiation.

Martínez-Pardo, Ma. E.; Cardoso, J.; Vázquez, H.; Aguilar, M.; Rickards, J.; Andrade, E.

1997-08-01

149

Dewetting Dynamics of PS on PMMA as a function of PS-PMMA diblock copolymer concentration at the interface  

NASA Astrophysics Data System (ADS)

We studied the dynamics of dewetting at the interface between PS and PMMA in the presence of symmetric diblock PS-PMMA copolymer. Optical microscopy was used to follow the dewetting process and quantify the dewetting velocities. AFM, combined with washing technique, was applied to image the surface and interfacial structure. PS-PMMA copolymers were added to the PS layer in concentrations up to 50wt%. SIMS experiments have been performed on selected samples to measure the amount of copolymer segregation to the interface. We observed that the dewetting process was drastically changed from that without copolymers. We determined the scaling behavior of the dewetting velocity as a function of the weight percentage of the diblock copolymer dPS-PMMA (40k-40k). Within the error of the experiment, the dewetting velocity was found to be constant in time on all PMMA substrates. On 330k PMMA, as the concentration of block copolymer increases, dewetting velocity first decreases and reaches its minimum at 30wt% of block copolymer, and then rises as a result of formation of a dense brush at the interface. On 27k PMMA, a microemulsion was produced when 30% of diblock copolymer is added.

Qu, S.; Liu, Y.; Rafailovich, M. H.; Johnathan, S.

1998-03-01

150

Effect of added homopolymer on structures of thin films of PS- b-PDMS/PS mixture under solvent vapor annealing  

NASA Astrophysics Data System (ADS)

Self assembly of poly(styrene- b-dimethylsiloxane) (PS- b-PDMS) followed by reactive ion etching technique is a promising method for fabricating periodical silica nanopatterns and can be applicable for device fabrication on nanoscale. We demonstrated a technologically useful way to control the inorganic silica nanostructures in thin films by directly mixing asymmetric (PS- b-PDMS) diblock copolymer with homopolymers of majority component, polystyrene (PS) under solvent vapor annealing followed by UV/O 3 treatment. The effects of molecular weight and volume fraction of added homopolymer (PS) on morphology and size of the nanostructure of blends have been carefully investigated by atomic force microscopy. Different morphology transitions observed on the ordering film surface by atomic force microscopy (AFM) are associated with kinetics of phase evolution with respect to homo-PS with different molecular weight. The periodic spacings and dimensions of the microdomains were readily tuned at the same time, just by adjusting the molecular weight and volume fraction of the blended homopolymer.

Yang, Jinghui; Wang, Qi; Yao, Weiwei; Chen, Feng; Fu, Qiang

2011-03-01

151

Inhibition of serine proteases by peptidyl fluoromethyl ketones  

SciTech Connect

Peptidyl fluoromethyl ketones that are specific inhibitors of the serine proteases ..cap alpha..-chymotrypsin and porcine pancreatic elastase were synthesized. By analogy with the corresponding aldehydes it is assumed that the fluoromethyl ketones react with the ..gamma..-OH group of the active site serine to form a stable hemiacetal. /sup 19/F NMR studies of the chymotrypsin-bound trifluoromethyl ketone inhibitors Ac-Leu-ambo-Phe-CF/sub 3//sup 1/ and Ac-ambo-Phe-CF/sub 3/ clearly indicate that the carbonyl carbon is tetrahedral at the active site of the enzyme. The inhibitor is bound as either the stable hydrat or the hemiacetal, involving the active site serine. The effect of varying the number of amino acid residues in the peptidyl portion of the inhibitor and the number of fluorines in the fluoromethyl ketone moiety is examined. In the series of trifluoromethyl ketone elastase inhibitors, the lowering of K/sub i/ concomitant with the change from a dipeptide analogue to a tetrapeptide analogue correlates well with the variation in V/K for hydrolysis of the corresponding amide substrates. This trend is indicative of the inhibitors acting as transition-state analogues. In addition to chain length, the number of fluorine substituents also affects the K/sub i/. In the case of chymotrypsin, the K/sub i/ for Ac-Leu-ambo-Phe-CF/sub 3/ is 30-fold lower than that for Ac-Leu-ambo-Phe-CF/sub 2/H. With elastase this trend is not as profound. In all cases, however, the difluoro- and trifluoromethyl ketones are better inhibitors than the monofluoromethyl and nonfluorinated analogues. This improvement must be associated with both the degree of hydration of the fluoromethyl ketones and the significant effect that fluorine substitution has on lowering the first pK/sub a/ of the hemiacetal hydroxyl. The monofluoromethyl ketone inhibitor of chymotrypsin, Ac-Leu-ambo-Phe-CFH/sub 2/, is a weak competitive inhibitor.

Imperiali, B.; Abeles, R.H.

1986-07-01

152

Role of Cytoplasmic Domain Serines in Intracellular Trafficking of Furin  

PubMed Central

Furin is a transmembrane protein that cycles between the plasma membrane, endosomes, and the trans-Golgi network, maintaining a predominant distribution in the latter. It has been shown previously that Tac-furin, a chimeric protein expressing the extracellular and transmembrane domains of the interleukin-2 receptor ? chain (Tac) and the cytoplasmic domain of furin, is delivered from the plasma membrane to the TGN through late endosomes, bypassing the endocytic recycling compartment. Tac-furin also recycles in a loop between the TGN and late endosomes. Localization of furin to the TGN is modulated by a six-amino acid acidic cluster that contains two phosphorylatable serines (SDSEED). We investigated the role of these serines in the trafficking of Tac-furin by using a mutant chimera in which the SDS sequence was replaced by the nonphosphorylatable sequence ADA (Tac-furin/ADA). Although the mutant construct is internalized and delivered to the TGN, both the postendocytic trafficking and the steady-state distribution were found to differ from the wild-type. In contrast with Tac-furin, Tac-furin/ADA does not enter late endosomes after being internalized. Instead, it traffics with transferrin to the endocytic recycling compartment, and from there it is delivered to the TGN. As with Tac-furin, Tac-furin/ADA is sorted from the TGN into late endosomes at steady state, but its retrieval from the late endosomes to the TGN is inhibited. These results suggest that serine phosphorylation plays an important role in at least two steps of Tac-furin trafficking, acting as an active sorting signal that mediates the selective sorting of Tac-furin into late endosomes after internalization, as well as its retrieval from late endosomes back to the TGN.

Schapiro, Florencia B.; Soe, Thwe Thwe; Mallet, William G.; Maxfield, Frederick R.

2004-01-01

153

Lead Dysregulates Serine/Threonine Protein Phosphatases in Human Neurons  

PubMed Central

It is well established that lead (Pb) exposure in humans leads to learning and memory impairment. However, the biological and molecular mechanisms are still not clearly understood. When over activated, serine/threonine protein phosphatases are known to function as a constraint on learning and memory. Activation of these phosphatases can also result in cytoskeletal changes that will adversely affect learning and memory. We investigated the effects of Pb exposure on these phosphatases in primary cultures of human neurons. Neurons were exposed to physiologically relevant concentrations of Pb (5, 10, 20 and 40 ?g/dL) and total phosphatase and PP2A activities were determined in neuronal lysate using para-nitrophenyl phosphate (pNPP), and a PP2A-specific phosphopeptide as substrates. Expression of various serine/threonine phosphatases, tau and its phosphorylation state were determined by Western blot (WB) and immunocytochemistry (ICC). We found that the total phosphatase activity in the neuronal lysate was increased by 30–50% by all the concentrations of Pb tested. PP2A activity was increased by 5 ?g/dL Pb only. PP1 expression was increased (ranging from 25–50%) by 10, 20 and 40 ?g/dL of Pb. PP2B expression was increased substantially (up to 2.5-fold) by 10 ?g/dL Pb, whereas, higher concentrations did not show any effect. On the other hand, Pb (at all concentrations used) decreased expression of PP2A and PP5. Pb exposure induced substantial hyperphosphorylation of tau at serine 199/202 by 5 and 10 ?g/dL Pb, and Threonine 231 at higher doses. Expression of total tau was mostly unaffected by lead. Immunocytochemistry data confirmed the WB results of expression of PP1, PP2A, tau protein and the phosphorylation of tau. These results support our hypothesis that Pb exposure up regulates some of the serine/threonine phosphatases (PP1 and PP2B) that are known to impair memory formation, and suggest a novel mechanism of Pb neurotoxicity.

Rahman, Abdur; Brew, Bruce J.

2010-01-01

154

Structural basis of substrate specificity in the serine proteases.  

PubMed Central

Structure-based mutational analysis of serine protease specificity has produced a large database of information useful in addressing biological function and in establishing a basis for targeted design efforts. Critical issues examined include the function of water molecules in providing strength and specificity of binding, the extent to which binding subsites are interdependent, and the roles of polypeptide chain flexibility and distal structural elements in contributing to specificity profiles. The studies also provide a foundation for exploring why specificity modification can be either straightforward or complex, depending on the particular system.

Perona, J. J.; Craik, C. S.

1995-01-01

155

Tenectin is a novel ?PS2?PS integrin ligand required for wing morphogenesis and male genital looping in Drosophila  

PubMed Central

Morphogenesis of the adult structures of holometabolous insects is regulated by ecdysteroids and juvenile hormones and involves cell-cell interactions mediated in part by the cell surface integrin receptors and their extracellular matrix (ECM) ligands. These adhesion molecules and their regulation by hormones are not well characterized. We describe the gene structure of a newly described ECM molecule, tenectin, and demonstrate that it is a hormonally regulated ECM protein required for proper morphogenesis of the adult wing and male genitalia. Tenectin’s function as a new ligand of the PS2 integrins is demonstrated by both genetic interactions in the fly and by cell spreading and cell adhesion assays in cultured cells. Its interaction with the PS2 integrins is dependent on RGD and RGD-like motifs. Tenectin’s function in looping morphogenesis in the development of the male genitalia led to experiments that demonstrate a role for PS integrins in the execution of left-right asymmetry.

Fraichard, Stephane; Bouge, Anne-Laure; Kendall, Timmy; Chauvel, Isabelle; Bouhin, Herve; Bunch, Thomas A.

2010-01-01

156

Phylogenetic analysis of serine proteases from Russell's viper (Daboia russelli siamensis) and Agkistrodon piscivorus leucostoma venom  

PubMed Central

Serine proteases are widely found in snake venoms. They have variety of functions including contributions to hemostasis. In this study, five serine proteases were cloned and characterized from two different cDNA libraries: factor V activator (RVV-V), alpha fibrinogenase (RVAF) and beta fibrinogenase (RVBF) from Russell's viper (Daboia russelli siamensis), and plasminogen activator (APL-PA) and protein C activator (APL-C) from Agkistrodon piscivorus leucostoma. The snake venom serine proteases were clustered in phylogenetic tree according to their functions. KA/KS values suggested that accelerated evolution has occurred in the mature protein coding regions in cDNAs of snake venom serine proteases.

Sukkapan, Pattadon; Jia, Ying; Nuchprayoon, Issarang; Perez, John C.

2012-01-01

157

Consistent scenario for B{yields}PS decays  

SciTech Connect

We consider B{yields}PS decays where P stands for pseudoscalar and S for a heavy (1500 MeV) scalar meson. We achieve agreement with available experimental data, which includes two orders of magnitude hierarchy, assuming the scalars mesons are two quark states. The contribution of the dipolar penguin operator O{sub 11} is quantified.

Delepine, D.; Lucio M, J. L.; Mendoza S, J. A.; Ramirez, Carlos A. [Instituto de Fisica, Universidad de Guanajuato Loma del Bosque 103, Lomas del Campestre, 37150 Leon, Guanajuato (Mexico); Depto. de Fisica-Matematicas, Universidad de Pamplona Pamplona, Norte de Santander (Colombia); Escuela de Fisica, Universidad Industrial de Santander, A.A. 678, Bucaramanga (Colombia)

2008-12-01

158

Framing Retention for Institutional Improvement: A 4 Ps Framework  

ERIC Educational Resources Information Center

|A 4 Ps framework for student retention strategy is a construct for reframing the retention discussion in a way that enables institutional improvement by challenging some conventional wisdom and prevailing perspectives that have characterized retention strategy for years. It opens new possibilities for action and improvement by suggesting that…

Kalsbeek, David H.

2013-01-01

159

BioMaPS: A Roadmap for Success  

ERIC Educational Resources Information Center

|The manuscript outlines the impact that our National Science Foundation Interdisciplinary Training for Undergraduates in Biological and Mathematical Sciences program, BioMaPS, has had on the students and faculty at Murray State University. This interdisciplinary program teams mathematics and biology undergraduate students with mathematics and…

McCarthy, Maeve L.; Fister, K. Renee

2010-01-01

160

PS-algol: an algol with a persistent heap  

Microsoft Academic Search

PS-algol is a dialect of algol for the programming of problems that would normally require a database management system. It supports a persistent heap, and an associative store; it has embedded within the language features to support tasks normally carried out by filing systems or database management systems.

Malcolm P. Atkinson; Kenneth Chisholm; Paul Cockshott

1982-01-01

161

3.3 ps SiGe bipolar technology  

Microsoft Academic Search

A SiGe bipolar technology with a transit frequency of 225 GHz and a maximum oscillation frequency of 300 GHz is described. With a ring oscillator gate delay of 3.3 ps and a static frequency divider operating up to 102 GHz input frequency state-of-the-art circuit performance is achieved.

J. Bock; H. Schafer; H. Knapp; K. Aufinger; M. Wurzer; S. Boguth; T. Bottner; R. Stengl; W. Perndl; T. F. Meister

2004-01-01

162

Microproteins (miPs) - the next big thing.  

PubMed

With iPS cells, sncRNAs, chromatin modification regulation and cancer stem cells already cooling off again, i.e. not being guaranteed publications in the 'ultimate' journals anymore, what will be very soon the new red-hot (or super-cool, i.e. anything but lukewarm) 'kid on the block'? We would vote for microproteins. PMID:23249432

Feller, Stephan

2012-12-18

163

Longitudinal coupled-bunch instabilities in the CERN PS  

Microsoft Academic Search

Longitudinal coupled bunch instabilities in the CERN PS represent a major limitation to the high brightness beam delivered for the LHC. To identify possible impedance sources for these instabilities, machine development studies have been carried out. The growth rates of coupled bunch modes have been measured, and modes have been identified using mountain range data. Growth rate estimations from coupled

H. Damerau; S. Hancock; C. Rossi; E. Shaposhnikova; J. Tuckmantel; J.-L. Vallet; M. Mehler

2007-01-01

164

Solvent annealing of Micropatterned PS-b-PEO copolymer films  

NASA Astrophysics Data System (ADS)

Solvent annealing of block copolymer thin films have been known as an effective way to control both orientation of microdomains with respect to the surface and their registration into a well ordered periodic lattice structure. We have recently demonstrated hierarchically ordered microdomains in a thin poly(styrene-b-ethylene oxide)(PS-b-PEO) film combined with microcontact printing. The solvent annealing gave rise to well ordered spherical PEO microdomains in large area by the confined dewetting of thin PS-b-PEO films which had been micropatterned on chemically modified surface during solvent annealing. In this presentation, we intentionally prepare a micropatterned dewet film of PS-b-PEO by spincoating a block copolymer solution on a topographic PDMS pre-pattern. Convex lens shaped spherical caps of PS-b-PEO individually located on each PDMS mesa were successfully transferred to a Si substrate by a conventional transfer printing technique. We investigate the effect of solvent on not only film wettability but also formation of hierarchical nanostructures.

Kim, Tae Hee; Acharya, Himadri; Joeng, Hee June; Park, Cheolmin

2009-03-01

165

BioMaPS: A Roadmap for Success  

ERIC Educational Resources Information Center

The manuscript outlines the impact that our National Science Foundation Interdisciplinary Training for Undergraduates in Biological and Mathematical Sciences program, BioMaPS, has had on the students and faculty at Murray State University. This interdisciplinary program teams mathematics and biology undergraduate students with mathematics and…

McCarthy, Maeve L.; Fister, K. Renee

2010-01-01

166

To the Teacher: P.S. Write Soon!  

ERIC Educational Resources Information Center

Intended for teachers of grades 4 through 8 who want to adapt the activities listed in the publication "P.S. Write Soon!" for classroom use, this guide provides chapter by chapter examples of the kinds of classroom projects suggested by the book that can be incorporated into an existing unit on letter writing or used as the basis for letter…

Post Office Dept., Washington, DC.

167

A novel serine protease inhibitor from Bungarus fasciatus venom.  

PubMed

By Sephadex G-50 gel filtration, cation-exchange CM-Sephadex C-25 chromatography and reversed phase high-performance liquid chromatography (HPLC), a novel serine protease inhibitor named bungaruskunin was purified and characterized from venom of Bungarus fasciatus. Its cDNA was also cloned from the cDNA library of B. fasciatus venomous glands. The predicted precursor is composed of 83 amino acid (aa) residues including a 24-aa signal peptide and a 59-aa mature bungaruskunin. Bungaruskunin showed maximal similarity (64%) with the predicted serine protease inhibitor blackelin deduced from the cDNA sequence of the red-bellied black snake Pseudechis porphyriacus. Bungaruskunin is a Kunitz protease inhibitor with a conserved Kunitz domain and could exert inhibitory activity against trypsin, chymotrypsin, and elastase. By screening the cDNA library, two new B chains of beta-bungarotoxin are also identified. The overall structures of bungaruskunin and beta-bungarotoxin B chains are similar; especially they have highly conserved signal peptide sequences. These findings strongly suggest that snake Kunitz/BPTI protease inhibitors and neurotoxic homologs may have originated from a common ancestor. PMID:18164783

Lu, Jia; Yang, Hailong; Yu, Haining; Gao, Weikai; Lai, Ren; Liu, Jingze; Liang, Xingcai

2007-11-26

168

Molecular Characterization of a Novel Staphylococcus aureus Serine Protease Operon  

PubMed Central

The present study identified and characterized a unique operon (spl) encoding six serine protease-like proteins. In addition, native Spl proteins were isolated and characterized. Typical of most exoproteins, the spl gene products contain putative 35- or 36-amino-acid signal peptides. The Spl proteins share 44 to 95% amino acid sequence identity with each other and 33 to 36% sequence identity with V8 protease. They also contain amino acids found in catalytic triads of enzymes in the trypsin-like serine protease family, and SplB and SplC were shown to degrade casein. The spl operon is transcribed on a 5.5-kb transcript, but several nonrandom degradation products of this transcript were also identified. Similar to other S. aureus exoprotein genes, the spl operon is maximally expressed during the transition into stationary phase and is positively controlled by the Agr virulence factor regulator. The Sar regulatory system did not affect spl operon expression. PCR analysis revealed the presence of the spl operon in 64% of the S. aureus isolates tested, although one spl operon-negative isolate was shown to contain at least two of the spl genes. Finally, intraperitoneal injection of an spl operon deletion mutant revealed no major differences in virulence compared to the parental strain.

Reed, Samantha B.; Wesson, Carla A.; Liou, Linda E.; Trumble, William R.; Schlievert, Patrick M.; Bohach, Gregory A.; Bayles, Kenneth W.

2001-01-01

169

The chemical basis of serine palmitoyltransferase inhibition by myriocin.  

PubMed

Sphingolipids (SLs) are essential components of cellular membranes formed from the condensation of l-serine and a long-chain acyl thioester. This first step is catalyzed by the pyridoxal-5'-phosphate (PLP)-dependent enzyme serine palmitoyltransferase (SPT) which is a promising therapeutic target. The fungal natural product myriocin is a potent inhibitor of SPT and is widely used to block SL biosynthesis despite a lack of a detailed understanding of its molecular mechanism. By combining spectroscopy, mass spectrometry, X-ray crystallography, and kinetics, we have characterized the molecular details of SPT inhibition by myriocin. Myriocin initially forms an external aldimine with PLP at the active site, and a structure of the resulting co-complex explains its nanomolar affinity for the enzyme. This co-complex then catalytically degrades via an unexpected 'retro-aldol-like' cleavage mechanism to a C18 aldehyde which in turn acts as a suicide inhibitor of SPT by covalent modification of the essential catalytic lysine. This surprising dual mechanism of inhibition rationalizes the extraordinary potency and longevity of myriocin inhibition. PMID:23957439

Wadsworth, John M; Clarke, David J; McMahon, Stephen A; Lowther, Jonathan P; Beattie, Ashley E; Langridge-Smith, Pat R R; Broughton, Howard B; Dunn, Teresa M; Naismith, James H; Campopiano, Dominic J

2013-09-11

170

Lacticin 481 Synthetase as a General Serine/Threonine Kinase  

PubMed Central

Methods that introduce posttranslational modifications in a general, mild, and non-sequence-specific manner using biologically produced peptides have great utility for investigation of the functions of these modifications. In this study, the substrate promiscuity of a lantibiotic synthetase was exploited for the preparation of phosphopeptides, glycopeptides, and peptides containing analogs of methylated or acetylated lysine residues. Peptides attached to the C-terminus of the leader peptide of the lacticin 481 precursor peptide were phosphorylated on serine residues in a wide variety of sequence contexts by the R399M and T405A mutants of lacticin 481 synthetase (LctM). Serine residues located as many as 30 amino acids C-terminal to the leader peptide were phosphorylated. Wild-type LctM was shown to dehydrate these peptides to generate dehydroalanine-containing products that can be conveniently modified with external nucleophiles including thiosaccharides, 2-(dimethylamino)ethanethiol, and N-acetyl cysteamine, resulting in mimics of O-linked glycopeptides and acetylated and methylated lysines.

2009-01-01

171

The structure of serine palmitoyltransferase; gateway to sphingolipid biosynthesis.  

PubMed

Sphingolipid biosynthesis commences with the condensation of L-serine and palmitoyl-CoA to produce 3-ketodihydrosphingosine (KDS). This reaction is catalysed by the PLP-dependent enzyme serine palmitoyltransferase (SPT; EC 2.3.1.50), which is a membrane-bound heterodimer (SPT1/SPT2) in eukaryotes such as humans and yeast and a cytoplasmic homodimer in the Gram-negative bacterium Sphingomonas paucimobilis. Unusually, the outer membrane of S. paucimobilis contains glycosphingolipid (GSL) instead of lipopolysaccharide (LPS), and SPT catalyses the first step of the GSL biosynthetic pathway in this organism. We report here the crystal structure of the holo-form of S. paucimobilis SPT at 1.3 A resolution. The enzyme is a symmetrical homodimer with two active sites and a monomeric tertiary structure consisting of three domains. The PLP cofactor is bound covalently to a lysine residue (Lys265) as an internal aldimine/Schiff base and the active site is composed of residues from both subunits, located at the bottom of a deep cleft. Models of the human SPT1/SPT2 heterodimer were generated from the bacterial structure by bioinformatics analysis. Mutations in the human SPT1-encoding subunit have been shown to cause a neuropathological disease known as hereditary sensory and autonomic neuropathy type I (HSAN1). Our models provide an understanding of how these mutations may affect the activity of the enzyme. PMID:17559874

Yard, Beverley A; Carter, Lester G; Johnson, Kenneth A; Overton, Ian M; Dorward, Mark; Liu, Huanting; McMahon, Stephen A; Oke, Muse; Puech, Daphné; Barton, Geoffrey J; Naismith, James H; Campopiano, Dominic J

2007-05-10

172

Cleavage activity of hepatitis C virus serine proteinase.  

PubMed

To study the character of the hepatitis C virus (HCV) encoding serine proteinase and to search for inhibitors, a practical in vitro assay system using the purified enzyme and synthetic peptide substrates was established. The enzyme used was expressed in Escherichia coli as a fusion form with protein tags and purified to apparent homogeneity by single-step affinity chromatography. The purified enzyme exhibited proteolytic activity with pH optima of around eight, and the addition of NS4A fragments increased the activity as well as the thermal stability of the enzyme. The activity was inhibited by EDTA and some divalent ions, i.e., copper and zinc, though calcium, magnesium, and manganese were stimulative both in the presence and absence of the NS4A fragment. None of the common protease inhibitors, including serine protease inhibitors, effectively inhibited the activity. Based on the kinetic parameters of the cleavage reaction of the synthetic 20 mer peptides corresponding to the three cleavage sites, NS4A/4B, NS4B/5A, and NS5A/5B, the peptide with the NS5A/5B junction was found to be the most efficient substrate. Analysis of the minimal peptide substrate of NS5A/5B indicated that 5 to 7 amino acids on both sides of the junction were required for efficient cleavage. These findings are expected to contribute to the search for a proteinase inhibitor. PMID:9399578

Kakiuchi, N; Komoda, Y; Hijikata, M; Shimotohno, K

1997-10-01

173

psRNATarget: a plant small RNA target analysis server  

PubMed Central

Plant endogenous non-coding short small RNAs (20–24 nt), including microRNAs (miRNAs) and a subset of small interfering RNAs (ta-siRNAs), play important role in gene expression regulatory networks (GRNs). For example, many transcription factors and development-related genes have been reported as targets of these regulatory small RNAs. Although a number of miRNA target prediction algorithms and programs have been developed, most of them were designed for animal miRNAs which are significantly different from plant miRNAs in the target recognition process. These differences demand the development of separate plant miRNA (and ta-siRNA) target analysis tool(s). We present psRNATarget, a plant small RNA target analysis server, which features two important analysis functions: (i) reverse complementary matching between small RNA and target transcript using a proven scoring schema, and (ii) target-site accessibility evaluation by calculating unpaired energy (UPE) required to ‘open’ secondary structure around small RNA’s target site on mRNA. The psRNATarget incorporates recent discoveries in plant miRNA target recognition, e.g. it distinguishes translational and post-transcriptional inhibition, and it reports the number of small RNA/target site pairs that may affect small RNA binding activity to target transcript. The psRNATarget server is designed for high-throughput analysis of next-generation data with an efficient distributed computing back-end pipeline that runs on a Linux cluster. The server front-end integrates three simplified user-friendly interfaces to accept user-submitted or preloaded small RNAs and transcript sequences; and outputs a comprehensive list of small RNA/target pairs along with the online tools for batch downloading, key word searching and results sorting. The psRNATarget server is freely available at http://plantgrn.noble.org/psRNATarget/.

Dai, Xinbin; Zhao, Patrick Xuechun

2011-01-01

174

PS-b-PAA as a high ? polymer for directed self-assembly: a study of solvent and thermal annealing processes for PS-b-PAA  

NASA Astrophysics Data System (ADS)

Poly(styrene)-b-poly(acrylic acid) copolymers (PS-b-PAA) was shown to be one promising material for achieving substantially smaller pitch patterns than PS-b-PMMA while still retaining high etch contrast and application for chemoepitaxy. Phase separation of acetone vapor annealed PS-b-PAA (Mw=16,000 g/mol with 50:50 volume ratio of PS: PAA) on PS brush achieved a lamellar morphology with a pattern pitch size (L0) of 30 nm. However the thermal annealing of the same PS-b-PAA generated a dramatically larger pitch size of 43 nm. SEM and GPC analysis revealed that the intermolecular crosslinking during thermal annealing process has increased the effective N (degree of polymerization), which suggests that even a small amount of crosslinking would lead to big pitch change. Thus, PS-b-PAA is not suitable for fast thermal annealing process as it loses pitch size control due to PAA crosslinking.

Cheng, Jing; Lawson, Richard A.; Yeh, Wei-Ming; Jarnagin, Nathan D.; Tolbert, Laren M.; Henderson, Clifford L.

2013-03-01

175

Regulatory phosphorylation of serine-15 in maize phosphoenolpyruvate carboxylase by a C4-leaf protein-serine kinase.  

PubMed

We have recently reported that the light-induced changes in the enzymatic and regulatory properties of maize leaf phosphoenolpyruvate carboxylase are attributed to the regulatory seryl phosphorylation of this C4-photosynthesis enzyme. In the present study, the darkform target enzyme was phosphorylated/activated in vitro by a maize leaf protein-serine kinase, and the 32P-labeled regulatory site phosphopeptide was purified from a tryptic digest by metal-ion affinity and reversed-phase chromatography. Automated Edman degradation analysis by covalent protein sequencing technology revealed that the amino acid sequence of this phosphoseryl peptide is His-His-Ser(P)-Ile-Asp-Ala-Gln-Leu-Arg. This nonapeptide, which corresponds exactly to residues 13-21 in the deduced primary sequence of the maize leaf carboxylase, is far removed from recently identified active-site cysteine (Cys-553) and lysine (Lys-606) residues in the C-terminal region of the primary structure. Comparative analysis of the deduced N-terminal sequences of C3-, C4-, and Crassulacean acid metabolism (CAM)-leaf phosphoenolpyruvate carboxylases suggests that the motif of Lys/Arg-X-X-Ser is an important structural requirement of the C4- and CAM-leaf protein-serine kinases. PMID:2148863

Jiao, J A; Chollet, R

1990-12-01

176

Metabolic engineering and flux analysis of Corynebacterium glutamicum for L-serine production.  

PubMed

L-Serine plays a critical role as a building block for cell growth, and thus it is difficult to achieve the direct fermentation of L-serine from glucose. In this study, Corynebacterium glutamicum ATCC 13032 was engineered de novo by blocking and attenuating the conversion of L-serine to pyruvate and glycine, releasing the feedback inhibition by L-serine to 3-phosphoglycerate dehydrogenase (PGDH), in combination with the co-expression of 3-phosphoglycerate kinase (PGK) and feedback-resistant PGDH (PGDH(r)). The resulting strain, SER-8, exhibited a lower specific growth rate and significant differences in L-serine levels from Phase I to Phase V as determined for fed-batch fermentation. The intracellular L-serine pool reached (14.22 ± 1.41) ?mol g(CDM) (-1), which was higher than glycine pool, contrary to fermentation with the wild-type strain. Furthermore, metabolic flux analysis demonstrated that the over-expression of PGK directed the flux of the pentose phosphate pathway (PPP) towards the glycolysis pathway (EMP), and the expression of PGDH(r) improved the L-serine biosynthesis pathway. In addition, the flux from L-serine to glycine dropped by 24%, indicating that the deletion of the activator GlyR resulted in down-regulation of serine hydroxymethyltransferase (SHMT) expression. Taken together, our findings imply that L-serine pool management is fundamental for sustaining the viability of C. glutamicum, and improvement of C(1) units generation by introducing the glycine cleavage system (GCV) to degrade the excessive glycine is a promising target for L-serine production in C. glutamicum. PMID:22566084

Lai, Shujuan; Zhang, Yun; Liu, Shuwen; Liang, Yong; Shang, Xiuling; Chai, Xin; Wen, Tingyi

2012-05-09

177

Brain-specific Phgdh Deletion Reveals a Pivotal Role for l-Serine Biosynthesis in Controlling the Level of d-Serine, an N-methyl-d-aspartate Receptor Co-agonist, in Adult Brain*  

PubMed Central

In mammalian brain, d-serine is synthesized from l-serine by serine racemase, and it functions as an obligatory co-agonist at the glycine modulatory site of N-methyl-d-aspartate (NMDA)-selective glutamate receptors. Although diminution in d-serine level has been implicated in NMDA receptor hypofunction, which is thought to occur in schizophrenia, the source of the precursor l-serine and its role in d-serine metabolism in adult brain have yet to be determined. We investigated whether l-serine synthesized in brain via the phosphorylated pathway is essential for d-serine synthesis by generating mice with a conditional deletion of d-3-phosphoglycerate dehydrogenase (Phgdh; EC 1.1.1.95). This enzyme catalyzes the first step in l-serine synthesis via the phosphorylated pathway. HPLC analysis of serine enantiomers demonstrated that both l- and d-serine levels were markedly decreased in the cerebral cortex and hippocampus of conditional knock-out mice, whereas the serine deficiency did not alter protein expression levels of serine racemase and NMDA receptor subunits in these regions. The present study provides definitive proof that l-serine-synthesized endogenously via the phosphorylated pathway is a key rate-limiting factor for maintaining steady-state levels of d-serine in adult brain. Furthermore, NMDA-evoked transcription of Arc, an immediate early gene, was diminished in the hippocampus of conditional knock-out mice. Thus, this study demonstrates that in mature neuronal circuits l-serine availability determines the rate of d-serine synthesis in the forebrain and controls NMDA receptor function at least in the hippocampus.

Yang, Jung Hoon; Wada, Akira; Yoshida, Kazuyuki; Miyoshi, Yurika; Sayano, Tomoko; Esaki, Kayoko; Kinoshita, Masami O.; Tomonaga, Shozo; Azuma, Norihiro; Watanabe, Masahiko; Hamase, Kenji; Zaitsu, Kiyoshi; Machida, Takeo; Messing, Albee; Itohara, Shigeyoshi; Hirabayashi, Yoshio; Furuya, Shigeki

2010-01-01

178

The temporal and spatial pattern of histone H3 phosphorylation at serine 28 and serine 10 is similar in plants but differs between mono- and polycentric chromosomes  

Microsoft Academic Search

Immunolabeling using site-specific antibodies against phosphorylated histone H3 at serine 10 or serine 28 revealed in plants an almost similar temporal and spatial pattern of both post-translational modification sites at mitosis and meiosis. During the first meiotic division the entire chromosomes are highly H3 phosphorylated. In the second meiotic division, like in mitosis, the chromosomes contain high phosphorylation levels in

D. Gernand; D. Demidov; A. Houben

2003-01-01

179

Characterization of polystyrene-binding peptides (PS-tags) for site-specific immobilization of proteins.  

PubMed

In this study, we characterized polystyrene-binding peptides (PS-tags) that possess a specific binding affinity for hydrophilic polystyrene (phi-PS) plates. Both the FITC-labeled PS19-1 (RAFIASRRIKRP) and PS19-6 (RIIIRRIRR) peptides showed strong binding affinity for commercially available hydrophilic, but not hydrophobic, PS plates in the presence of the non-ionic surfactant Tween 20. The dissociation constants (K(d)) of the PS19-1 and PS19-6 peptides for the hydrophilic PS-A plate were 169 and 86 nM, respectively, and the K(d) of both peptides increased with the concentration of NaCl or urea. Based on adsorption yield and residual activity of glutathione S-transferase (GST) after fusion with the PS19-6 peptide or its variants, it was found that the basic amino acid in the PS-tags, i.e., Arg was essential for the strong binding affinity of PS-tags in both the peptide and peptide-fused protein forms The aliphatic amino acids in PS19-6 and PS19-6L, such as Ile or Leu, were also effective. Thus, a series of PS-tags that possess this unusual feature, especially the peptides PS19-6 (RIIIRRIRR) and PS19-6L (RLLLRRLRR), are potential candidate affinity peptide tags for site-specific immobilization of proteins onto hydrophilic PS plates, which show potential as solid supports for protein-based biochips. PMID:20471598

Kumada, Yoichi; Kuroki, Daisuke; Yasui, Hidefumi; Ohse, Takuhito; Kishimoto, Michimasa

2009-12-14

180

Functional Characterization of Calcineurin Homologs PsCNA1/PsCNB1 in Puccinia striiformis f. sp. tritici Using a Host-Induced RNAi System  

PubMed Central

Calcineurin plays a key role in morphogenesis, pathogenesis and drug resistance in most fungi. However, the function of calcineurin genes in Puccinia striiformis f. sp. tritici (Pst) is unclear. We identified and characterized the calcineurin genes PsCNA1 and PsCNB1 in Pst. Phylogenetic analyses indicate that PsCNA1 and PsCNB1 form a calcium/calmodulin regulated protein phosphatase belonging to the calcineurin heterodimers composed of subunits A and B. Quantitative RT-PCR analyses revealed that both PsCNA1 and PsCNB1 expression reached their maximum in the stage of haustorium formation, which is one day after inoculation. Using barely stripe mosaic virus (BSMV) as a transient expression vector in wheat, the expression of PsCNA1 and PsCNB1 in Pst was suppressed, leading to slower extension of fungal hyphae and reduced production of urediospores. The immune-suppressive drugs cyclosporin A and FK506 markedly reduced the germination rates of urediospores, and when germination did occur, more than two germtubes were produced. These results suggest that the calcineurin signaling pathway participates in stripe rust morphogenetic differentiation, especially the formation of haustoria during the early stage of infection and during the production of urediospores. Therefore PsCNA1 and PsCNB1 can be considered important pathogenicity genes involved in the wheat-Pst interaction.

Zhang, Hong; Guo, Jun; Voegele, Ralf T.; Zhang, Jinshan; Duan, Yinghui; Luo, Huaiyong; Kang, Zhensheng

2012-01-01

181

Crystallographic Refinement by Incorporation of Molecular Dynamics: Thermostable Serine Protease Thermitase Complexed with Eglin c  

Microsoft Academic Search

In order to investigate the principles of protein thermostability, the crystal structure of thermitase from Thermoactinomyces vulgaris, a thermostable member of the subtilisin family of serine proteases, has been determined in a complex with eglin c. Eglin c is a serine protease inhibitor from the leech Hirudo medicinalis. After data collection with a television area-detector diffractometer and initial structure solution

Wim G. J. Hol; Kor H. Kalk; Bauke W. Dijkstra; Masao Fujinaga; Piet Gros

1989-01-01

182

STAT3 serine phosphorylation by ERK-dependent and -independent pathways negatively modulates its tyrosine phosphorylation.  

PubMed Central

Recent studies have indicated that serine phosphorylation regulates the activities of STAT1 and STAT3. However, the kinase(s) responsible and the role of serine phosphorylation in STAT function remain unresolved. In the present studies, we examined the growth factor-dependent serine phosphorylation of STAT1 and STAT3. We provide in vitro and in vivo evidence that the ERK family of mitogen-activated protein (MAP) kinases, but not JNK or p38, specifically phosphorylate STAT3 at serine 727 in response to growth factors. Evidence for additional mitogen-regulated serine phosphorylation is also provided. STAT1 is a relatively poor substrate for all MAP kinases tested both in vitro and in vivo. STAT3 serine phosphorylation, not its tyrosine phosphorylation, results in retarded mobility of the STAT3 protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Importantly, serine 727 phosphorylation negatively modulates STAT3 tyrosine phosphorylation, which is required for dimer formation, nuclear translocation, and the DNA binding activity of this transcriptional regulator. Interestingly, the cytokine interleukin-6 also stimulates STAT3 serine phosphorylation, but in contrast to growth factors, this occurs by an ERK-independent process.

Chung, J; Uchida, E; Grammer, T C; Blenis, J

1997-01-01

183

Sulfonyl fluoride analogues as activity-based probes for serine proteases.  

PubMed

Enriched with fluoride: To expand on the available tools to interrogate proteases, we explored sulfonyl fluorides as activity-based probes. An alkyne-tagged sulfonyl fluoride covalently modifies members of the S1 family of serine proteases. By applying click chemistry, avidin enrichment and mass spectrometry, we can enrich and identify active endogenous serine proteases from a complex proteome. PMID:23008217

Shannon, D Alexander; Gu, Christian; McLaughlin, Christopher J; Kaiser, Markus; van der Hoorn, Renier A L; Weerapana, Eranthie

2012-09-24

184

COMPARATIVE ANALYSIS OF SERINE PROTEASE-RELATED GENES IN THE HONEY BEE GENOME.  

Technology Transfer Automated Retrieval System (TEKTRAN)

We have identified 44 serine protease (SP) and 13 serine protease homolog (SPH) genes in the genome of Apis mellifera. Most of these genes encode putative secreted proteins, but 4 SPs and 3 SPHs may associate with the plasma membrane via a transmembrane region. Clip domains represent the most abunda...

185

Subtilases: the superfamily of subtilisin-like serine proteases.  

PubMed Central

Subtilases are members of the clan (or superfamily) of subtilisin-like serine proteases. Over 200 subtilases are presently known, more than 170 of which with their complete amino acid sequence. In this update of our previous overview (Siezen RJ, de Vos WM, Leunissen JAM, Dijkstra BW, 1991, Protein Eng 4:719-731), details of more than 100 new subtilases discovered in the past five years are summarized, and amino acid sequences of their catalytic domains are compared in a multiple sequence alignment. Based on sequence homology, a subdivision into six families is proposed. Highly conserved residues of the catalytic domain are identified, as are large or unusual deletions and insertions. Predictions have been updated for Ca(2+)-binding sites, disulfide bonds, and substrate specificity, based on both sequence alignment and three-dimensional homology modeling.

Siezen, R. J.; Leunissen, J. A.

1997-01-01

186

Aromatase is phosphorylated in situ at Serine-118  

PubMed Central

Phosphorylation of the cytochrome P450 aromatase has been proposed as a switch to rapidly modulate enzymatic activity and estrogen biosynthesis. Herein, we demonstrate that aromatase serine-118 is a potential phosphorylation site in mammalian cells. The amino acid context surrounding S118 is highly conserved among diverse animal species and suggests that an AGC-like kinase may phosphorylate aromatase. Mutation of S118 to Ala blocked phosphorylation. Mutation of S118 to either Ala or Asp destabilized aromatase, indicating an important structural role for S118. The phosphomimetic S118D mutant showed decreased specific enzymatic activity, decreased Vmax, and increased Km, while the S118A phospho-inhibiting mutant showed opposite effects. Our findings suggest that phosphorylation of S118 may decrease aromatase activity, presenting a mechanism whereby kinase signaling may modulate estrogen production and hormone balance.

Miller, Todd W.; Shin, Incheol; Kagawa, Norio; Evans, Dean B.; Waterman, Michael R.; Arteaga, Carlos L.

2010-01-01

187

Type II transmembrane serine protease (TTSP) deregulation in cancer.  

PubMed

The Type II transmembrane serine proteases (TTSP) are a relatively newly identified family of proteolytic enzymes that have become the subject of intense scrutiny in the field of cancer research. Advances in genome screening technology have enabled the identification of putative members and the further characterization of existing members. The TTSPs are involved in a diverse range of physiological functions and new roles continue to be discovered. A large majority of these proteases appear to play crucial roles in the development of disease, especially cancer development and progression. This review presents the current knowledge of the biological role of those TTSPs that have been identified in the development and progression of human cancers. PMID:21196187

Webb, Siobhan L; Sanders, Andrew J; Mason, Malcolm D; Jiang, Wen G

2011-01-01

188

Large serine recombinase domain structure and attachment site binding.  

PubMed

Abstract Large serine recombinases (LSRs) catalyze the movement of DNA elements into and out of bacterial chromosomes using site-specific recombination between short DNA "attachment sites". The LSRs that function as bacteriophage integrases carry out integration between attachment sites in the phage (attP) and in the host (attB). This process is highly directional; the reverse excision reaction between the product attL and attR sites does not occur in the absence of a phage-encoded recombination directionality factor, nor does recombination typically occur between other pairings of attachment sites. Although the mechanics of strand exchange are reasonably well understood through studies of the closely related resolvase and invertase serine recombinases, many of the fundamental aspects of the LSR reactions have until recently remained poorly understood on a structural level. In this review, we discuss the results of several years worth of biochemical and molecular genetic studies of LSRs in light of recently described structural models of LSR-DNA complexes. The focus is understanding LSR domain structure, how LSRs bind to the attP and attB attachment sites, and the differences between attP-binding and attB-binding modes. The simplicity, site-selectivity and strong directionality of the LSRs has led to their use as important tools in a number of genetic engineering applications in a wide variety of organisms. Given the important potential role of LSR enzymes in genetic engineering and gene therapy, understanding the structure and DNA-binding properties of LSRs is of fundamental importance for those seeking to enhance or alter specificity and functionality in these systems. PMID:23980849

Van Duyne, Gregory D; Rutherford, Karen

2013-08-28

189

The CERN PS/SL Controls Java Application Programming Interface  

SciTech Connect

The PS/SL Convergence Project was launched in March 1998. Its objective is to deliver a common control as infrastructure for the CERN accelerators by year 2001. In the framework of this convergence activity, a project was launched to develop a Java Application Programming Interface (API) between programs written in the Java language and the PS and SL accelerator equipment. This Java API was specified and developed in collaboration with TJNAF. It is based on the Java CDEV [1] package that has been extended in order to end up with a CERN/TJNAF common product. It implements a detailed model composed of devices organized in named classes that provide a property-based interface. It supports data subscription and introspection facilities. The device model is presented and the capabilities of the API are described with syntax examples. The software architecture is also described.

I. Deloose; J. Cuperus; P. Charrue; F. DiMaio; K. Kostro; M. Vanden Eynden (CERN); W. Watson (TJNAF)

1999-10-01

190

Four-frame gated optical imager with 120-ps resolution  

SciTech Connect

In this paper we describe the operation and applications of a framing camera capable of four separate two-dimensional images with each frame having a 120-ps gate width. Fast gating of a single frame is accomplished by using a wafer image intensifier tube in which the cathode is capacitively coupled to an external electrode placed outside of the photocathode of the tube. This electrode is then pulsed relative to the microchannel plate by a narrow (120 ps), high-voltage pulse. Multiple frames are obtained by using multiple gated tubes which share a single bias supply and pulser with relative gate times selected by the cable lengths between the tubes and the pulser. A beamsplitter system has been constructed which produces a separate image for each tube from a single scene. Applications of the framing camera to inertial confinement fusion experiments are discussed.

Young, P.E.; Hares, J.D.; Kilkenny, J.D.; Phillion, D.W.; Campbell, E.M.

1988-04-01

191

Spectra and relaxation dynamics of the pseudohalide (PS) vibrational bands for Ru(bpy)2(PS)2 complexes, PS = CN, NCS and N3  

NASA Astrophysics Data System (ADS)

Static and transient infrared spectroscopy were used to investigate cis-Ru(bpy)2(N3)2 (bpy = 2,2?-bipyridine), cis-Ru(bpy)2(NCS)2, and cis-Ru(bpy)2(CN)2 in solution. The NC stretching IR band for cis-Ru(bpy)2(NCS)2 appears at higher frequency (˜2106 cm?1 in DMSO) than for the free NCS? anion while the IR bands for the azide and cyanide complexes are closer to those of the respective free anions. The vibrational energy relaxation (VER) lifetime for the azide complex is found to be much shorter (˜5 ps) than for either the NCS or CN species (both ˜70 ps in DMSO) and the lifetimes resemble those for each corresponding free anion in solution. However, for cis-Ru(bpy)2(N3)2, it is determined that the transition frequency depends more on the solvent than the VER lifetime implying that intramolecular vibrational relaxation is predominant over solvent energy-extracting interactions. These results are compared to the behavior of other related metal complexes in solution.

Compton, Ryan; Gerardi, Helen K.; Weidinger, Daniel; Brown, Douglas J.; Dressick, Walter J.; Heilweil, Edwin J.; Owrutsky, Jeffrey C.

2013-08-01

192

Amperometric microbiosensor as an alternative tool for investigation of D-serine in brain.  

PubMed

This paper discusses the application of a reagentless, selective microbiosensor as a useful alternative tool for monitoring D-serine in neural samples. The main components of the 125-?m-diameter disk biosensor were D-amino acid oxidase for D-serine sensitivity (linear region slope, 61 ± 7 ?A cm(-2) mM(-1); limit of detection, 20 nM), and poly-phenylenediamine for rejection of electroactive interference. The response time of the biosensor was of the order of 1 s, ideal for 'real-time' monitoring, and detection of systemically administered D-serine in brain extracellular fluid is demonstrated. Exploitation of this probe might resolve queries involving regulation of D-serine in excitotoxicity, and modulation of N-methyl-D-aspartate receptor function by D-serine and glycine in the central nervous system. PMID:22865247

Mohd Zain, Zainiharyati; Ab Ghani, Sulaiman; O'Neill, Robert D

2012-08-04

193

Serine is a natural ligand and allosteric activator of pyruvate kinase M2.  

PubMed

Cancer cells exhibit several unique metabolic phenotypes that are critical for cell growth and proliferation. Specifically, they overexpress the M2 isoform of the tightly regulated enzyme pyruvate kinase (PKM2), which controls glycolytic flux, and are highly dependent on de novo biosynthesis of serine and glycine. Here we describe a new rheostat-like mechanistic relationship between PKM2 activity and serine biosynthesis. We show that serine can bind to and activate human PKM2, and that PKM2 activity in cells is reduced in response to serine deprivation. This reduction in PKM2 activity shifts cells to a fuel-efficient mode in which more pyruvate is diverted to the mitochondria and more glucose-derived carbon is channelled into serine biosynthesis to support cell proliferation. PMID:23064226

Chaneton, Barbara; Hillmann, Petra; Zheng, Liang; Martin, Agnès C L; Maddocks, Oliver D K; Chokkathukalam, Achuthanunni; Coyle, Joseph E; Jankevics, Andris; Holding, Finn P; Vousden, Karen H; Frezza, Christian; O'Reilly, Marc; Gottlieb, Eyal

2012-10-14

194

SIMION PC\\/PS2 electrostatic lens design program  

Microsoft Academic Search

SIMION PC\\/PS2 4.02 is a personal computer program for designing and analyzing charged particle (ions and electrons) lenses, ion transport systems, and various types of mass spectrometers and surface probes that utilize charged particles. The modification of an existing design or the generation of a completely new one is performed interactively with a graphics screen and mouse. Once the geometry

D. A. Dahl; J. E. Delmore; A. D. Appelhans

1990-01-01

195

Sub 5 ps SiGe bipolar technology  

Microsoft Academic Search

A SiGe bipolar technology for mixed digital and analog RF applications is presented. Balanced device performance is achieved with a transit frequency fT of 155 GHz at a collector emitter breakdown voltage BVCEO of 1.9 V, a maximum oscillation frequency fmax of 167 GHz, and 4.7 ps ring oscillator gate delay. With a 99 GHz dynamic frequency divider and a

J. Bock; H. Schafer; H. Knapp; D. Zoschg; K. Aufinger; M. Wurzer; S. Boguth; M. Rest; R. Schreiter; R. Stengl; T. F. Meister

2002-01-01

196

Sub-ns and ps laser performance and results  

NASA Astrophysics Data System (ADS)

In the field of ablative-based material processing there is a desire to use short pulse width (subns) laser sources. If the pulse width is too long <10 ns the processing is fast, but crude. If the pulse width is too short <10 ps the processing is precise, but slow. In an effort to balance the process fidelity with material removal rate, a unique TEM00 mode quality sub-ns (~0.5 ns nominal pulse width) laser was developed.

Kilmer, J.; Terraciano, M.; Yin, Y.

2013-03-01

197

Shear Wave Velocity Estimation Using PS Converted-Wave  

NASA Astrophysics Data System (ADS)

Shear (S-) wave velocity structure over the basement is one of the key elements for the estimation of strong ground motion generated by earthquakes. PS converted-wave reflection survey is superior to S-wave reflection survey in imaging the deeper structure, thus give us the deeper S-wave velocity information. But in the large Vp/Vs area, conventional velocity analysis and RMS velocity assumption fails to give us a good estimate of the S-wave velocity. The P-wave velocity derived from the velocity analysis is relatively reliable. When we get good images in both P-wave and PS converted-wave sections, correlation of the reflectors in the two sections gives us good estimates for Vp/Vs. Using these Vp/Vs values and P-wave velocities derived from P-wave velocity analysis, we can calculate S-wave velocities. We applied this methodology to a 3-component survey at Fuchu, Tokyo in Japan. The survey line was along the river and there is a well near by which is deep enough to reach the basement, about 2000m. The source was two vibrators. Three-component geophones are set in 10m interval. Geophones are fixed in 192 locations. The source-line was 3080m long so that we can get long offset data to use in PS converted-wave processing. From the P-wave sections, we can see the strata are inclining towards east. P-S converted-wave section has a good agreement with P-wave section. By correlation of the two sections, we derived Vp/Vs map of the section. Then we calculated the S-wave velocity using Vp/Vs value and P-wave velocity. We compared the velocity structure with the well log data. The derived S-wave velocities, ranging from 570m/s to 1780m/s, are in good agreement with the well data.

Kano, N.; Yokokura, T.; Yamaguichi, K.; Kiguchi, T.

2003-12-01

198

The four "P"s of marketing are dead.  

PubMed

For several decades marketing planning in the United States has relied upon the "four Ps" model. Product, price, place, and promotion were considered the foundation of the marketing mix. This model, however, has never been a comfortable fit for health care and, as the new century dawns, we find that a new marketing model--emphasizing the "four Rs"--is emerging. The foundations of the new model are relevance, response, relationships, and results. PMID:11183425

English, J

2000-01-01

199

Evidence of excited state absorption in PS II membrane fragments  

Microsoft Academic Search

Utilizing a two-beam technique in the frequency domain, the pumped absorption of PS II membrane fragments from spinach and of acetonic chlorophyll-a solutions was measured at room temperature. In a very narrow wavelength region (0.2 nm around the pump pulse wavelength) the relative test beam transmission exhibited either a decrease or an increase, respectively, dependent on the intensity of a

Th. Bittner; J. Voigt; G. Kehrberg; H.-J. Eckert; G. Renger

1991-01-01

200

Shear Wave Velocity Estimation Using PS Converted-Wave  

Microsoft Academic Search

Shear (S-) wave velocity structure over the basement is one of the key elements for the estimation of strong ground motion generated by earthquakes. PS converted-wave reflection survey is superior to S-wave reflection survey in imaging the deeper structure, thus give us the deeper S-wave velocity information. But in the large Vp\\/Vs area, conventional velocity analysis and RMS velocity assumption

N. Kano; T. Yokokura; K. Yamaguichi; T. Kiguchi

2003-01-01

201

PS3 CELL Development for Scientific Computation and Research  

NASA Astrophysics Data System (ADS)

The Cell processor is one of the most powerful processors on the market, and researchers in the earth sciences may find its parallel architecture to be very useful. A cell processor, with 7 cores, can easily be obtained for experimentation by purchasing a PlayStation 3 (PS3) and installing linux and the IBM SDK. Each core of the PS3 is capable of 25 GFLOPS giving a potential limit of 150 GFLOPS when using all 6 SPUs (synergistic processing units) by using vectorized algorithms. We have used the Cell's computational power to create a program which takes simulated tsunami datasets, parses them, and returns a colorized height field image using ray casting techniques. As expected, the time required to create an image is inversely proportional to the number of SPUs used. We believe that this trend will continue when multiple PS3s are chained using OpenMP functionality and are in the process of researching this. By using the Cell to visualize tsunami data, we have found that its greatest feature is its power. This fact entwines well with the needs of the scientific community where the limiting factor is time. Any algorithm, such as the heat equation, that can be subdivided into multiple parts can take advantage of the PS3 Cell's ability to split the computations across the 6 SPUs reducing required run time by one sixth. Further vectorization of the code can allow for 4 simultanious floating point operations by using the SIMD (single instruction multiple data) capabilities of the SPU increasing efficiency 24 times.

Christiansen, M.; Sevre, E.; Wang, S. M.; Yuen, D. A.; Liu, S.; Lyness, M. D.; Broten, M.

2007-12-01

202

Breast Cancer-Associated pS2 Protein: Synthesis and Secretion by Normal Stomach Mucosa  

NASA Astrophysics Data System (ADS)

The human pS2 gene is specifically expressed under estrogen transcriptional control in a subclass of estrogen receptor-containing human breast cancer cells. The pS2 gene encodes an 84-amino acid protein that is secreted after signal peptide cleavage. The distribution of pS2 protein in normal human tissues was studied with antibodies to pS2; pS2 was specifically expressed and secreted by mucosa cells of the normal stomach antrum and body of both female and male individuals. Moreover, no estrogen receptor could be detected in these cells, indicating that pS2 gene expression is estrogen-independent in the stomach. The function of the pS2 protein in the gastrointestinal tract is unknown. However, the pS2 protein is similar in sequence to a porcine pancreatic protein that has been shown to inhibit gastrointestinal motility and gastric secretion.

Rio, M. C.; Bellocq, J. P.; Daniel, J. Y.; Tomasetto, C.; Lathe, R.; Chenard, M. P.; Batzenschlager, A.; Chambon, P.

1988-08-01

203

Anomalous high ionic conductivity of nanoporous ?-Li3PS4.  

PubMed

Lithium-ion-conducting solid electrolytes hold promise for enabling high-energy battery chemistries and circumventing safety issues of conventional lithium batteries. Achieving the combination of high ionic conductivity and a broad electrochemical window in solid electrolytes is a grand challenge for the synthesis of battery materials. Herein we show an enhancement of the room-temperature lithium-ion conductivity by 3 orders of magnitude through the creation of nanostructured Li(3)PS(4). This material has a wide electrochemical window (5 V) and superior chemical stability against lithium metal. The nanoporous structure of Li(3)PS(4) reconciles two vital effects that enhance the ionic conductivity: (1) the reduction of the dimensions to a nanometer-sized framework stabilizes the high-conduction ? phase that occurs at elevated temperatures, and (2) the high surface-to-bulk ratio of nanoporous ?-Li(3)PS(4) promotes surface conduction. Manipulating the ionic conductivity of solid electrolytes has far-reaching implications for materials design and synthesis in a broad range of applications, including batteries, fuel cells, sensors, photovoltaic systems, and so forth. PMID:23305294

Liu, Zengcai; Fu, Wujun; Payzant, E Andrew; Yu, Xiang; Wu, Zili; Dudney, Nancy J; Kiggans, Jim; Hong, Kunlun; Rondinone, Adam J; Liang, Chengdu

2013-01-14

204

Anomalous high ionic conductivity of nanoporous -Li3PS4  

SciTech Connect

Lithium-ion conducting solid electrolytes hold the promise for enabling high-energy battery chemistries and circumventing safety issues of conventional lithium batteries1-3. Achieving the combination of high ionic conductivity and broad electrochemical window in solid electrolytes is a grand challenge for the synthesis of battery materials. Herein we show an enhancement of room-temperature lithium-ion conductivity of 3 orders of magnitude by creating nanostructured Li3PS4. This material has a wide (5V) electrochemical window and superior chemical stability against lithium metal. The nanoporous structure of Li3PS4 reconciles two vital effects that enhance ionic conductivity: (1) The reduced dimension to nanometer-sized framework stabilizes the high conduction beta phase that occurs at elevated temperatures1,4; and (2) The high surface-to-bulk ratio of nanoporous -Li3PS4 promotes surface conduction5,6. Manipulating the ionic conductivity of solid electrolytes has far-reaching implications for materials design and synthesis in a broad range of applications such as batteries, fuel-cells, sensors, photovoltaic systems, and so forth3,7.

Liu, Zengcai [ORNL; Fu, Wujun [ORNL; Payzant, E Andrew [ORNL; Yu, Xiang [ORNL; Wu, Zili [ORNL; Dudney, Nancy J [ORNL; Kiggans, Jim [ORNL; Hong, Kunlun [ORNL; Rondinone, Adam Justin [ORNL; Liang, Chengdu [ORNL

2013-01-01

205

Investigation of methylamine intercalated FePS3  

NASA Astrophysics Data System (ADS)

The 57Fe Mossbauer spectroscopic results of methylamine intercalated layered FePS3 following the removal of the guest species from the initial intercalate in steps by heating at three different stages are presented. The initial intercalate described as [FePS3-xOx]2x- [CH3NH3]2x+ (CH3NH2)y (H2O)z with x=0.65 has the host lattice of FePS3 modified through substitution of sulphur by oxygen due to intercalation of amine in aqueous medium and the neutral molecules, viz., water and methylamine solvating the ionised methylamine guest [CH3NH3]+. The present Mossbauer results show that when the guest species are removed by heating, 15% delocalised electrons present in the initial intercalate, get localised at the iron centres of the host. The most interesting feature of the Mössbauer result is the detection of a new kind of intercalation process wherein in situ generation of large amount of ionised amines takes place when the initial intercalate is simply heated above 100 degC.

Bhowmick, A.; Ganguli, S.; Bhattacharya, M.

1999-06-01

206

Thermal and mechanical properties of microcellular thermoplastic SBS\\/PS\\/SBR blend: effect of crosslinking  

Microsoft Academic Search

This study investigates the effect of peroxide crosslinking on the structure and mechanical properties for SBS\\/PS\\/SBR foams composed of polystyrene (PS), poly(styrene-b-butadiene) diblock copolymer (SBR-1502), and poly(styrene-b-butadiene-b-styrene) triblock copolymer (SBS). The cell size and its distribution of SBS\\/PS\\/SBR foams were investigated by SEM images, showing the smaller and denser of hollow cells for the SBS\\/PS\\/SBR foam containing the higher concentration

Ruey-Sheng Shih; Shiao-Wei Kuo; Feng-Chih Chang

2011-01-01

207

Reactively formed block and graft copolymers as compatibilizers for polyamide 66\\/PS blends  

Microsoft Academic Search

Phthalic anhydride terminated polystyrene (PS-An) and styrene-maleic anhydride copolymer (SMA) were compared as a compatibilizer at low loadings (<10wt%) in 70\\/30 polyamide 66 (PA66)\\/polystyrene (PS) blends. Compatibilization efficiency was judged by morphology of the blends and the extent of interfacial coupling to copolymer. Fluorescent labels of functional PS's (anthracene and pyrene for PS-An and SMA, respectively) allowed the detection of

Hyun K. Jeon; Benjamin J. Feist; Sok Boon Koh; Kwanho Chang; Christopher W. Macosko; Robert P. Dion

2004-01-01

208

?-Porous silicon (?PS) gas sensor based on interdigitated ?-electrodes (ID?E's)  

Microsoft Academic Search

A ?-porous silicon (?PS) gas sensor based on interdigitated ?-electrodes (ID?E's) has been designed and developed. ?PS obtained by means of electrochemical anodization of a p-type silicon (c-Si) wafer was used as active layer. The ?PS layers are supported by the bulk of the c-Si wafer. Interdigitated ?-electrodes, which work as transducers, were deposited on the ?PS surface by means

Enrique Valera; O. Casals; M. Vetter; A. Rodriguez

2007-01-01

209

Effects of Serine Protease Inhibitors on Growth and Development and Digestive Serine Proteinases of the Sunn Pest, Eurygaster integriceps  

PubMed Central

In the current study the effects of serine proteinase inhibitors (TLCK, TPCK, SBTI, and a combination of SBTI and TPCK) with concentrations of 1% and 4% of dietary protein in artificial diets were tested against growth of the Sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), development, and its gut serine proteinase targets. Analysis of variance indicated that protease inhibitors affected nymphal development time, adult weight, and survival. Mean development time of third instar nymphs in control, SBTI (1%), TLCK (1%), and TPCK was 7.18, 9.74, 9.97, and 8.52 days, respectively. The highest mortality (100 % mortality) was observed when a combination of TPCK and SBTI, both at 4% of dietary protein, was used followed by TPCK (4%) that produced 95% mortality. There were significant differences in proteinase activity between treatments and controls when BApNA and SAAPFpNA were used as substrates for trypsin and chymotrypsin, respectively. Reduction of trypsin activity in insects fed with low doses of SBTI (1%), TLCK (1%), and both doses of TPCK (1% and 4%) was 40, 26, 23, and 17%, respectively. Inhibition of chymotrypsin activity was seen in the insects fed on SBTI (1%), TLCK (1%), and TPCK (4%) where inhibition was 14, 9, and 36%, respectively. Maximum inhibition of chymotrypsin activity was observed in the insects fed on diets containing high doses of TPCK (4%). In gel assays, the greatest effects were observed when E. integriceps were fed on high doses of SBTI and TPCK. Therefore, TPCK followed by SBTI proved to be the most effective proteinase inhibitors of E. integriceps.

Saadati, Fatemeh; Bandani, Ali R.

2011-01-01

210

Communicating Knowing through Communities of Practice: Exploring Internal Communicative Processes and Differences among CoPs  

ERIC Educational Resources Information Center

|Knowing is an enacted, communicated process that is difficult to observe, let alone manage, in organizations. Communities of practice (CoPs) offer a productive solution for improving knowledge and knowledge management, but the communicative processes that enact CoPs have not been explored, leaving CoPs as an organizational black box. This…

Iverson, Joel O.; McPhee, Robert D.

2008-01-01

211

Recurrent trisomy and Robertsonian translocation of chromosome 14 in murine iPS cell lines.  

PubMed

Induced pluripotent stem (iPS) cells have greatly provoked people's interest due to their enormous potential of clinical applications. Increasing care is taken with the genetic safety of iPS cells. However, up to now, the chromosomal integrity of murine iPS (miPS) cells has been largely unknown. We have observed recurrent trisomy and/or Robertsonian translocation (Rb) of chromosome 14 in six out of nine independent miPS cell lines from three laboratories by G-banding, fluorescence in situ hybridization (FISH) and spectral karyotyping (SKY) analyses, while all the miPS cell lines were derived from mouse embryonic fibroblasts (MEFs) or neural precursor cells (NPCs) with a normal karyotype. The miPS cells with trisomy and/or Rb of chromosome 14 showed growth advantage over the miPS cells with a normal karyotype. We found a significantly higher frequency of Rbs in the miPS cell lines induced with c-Myc than those without c-Myc. Our findings demonstrate that miPS cell lines have the propensity for chromosomal aberrations and there is an obvious correlation between the extent of chromosomal aberrations in miPS cells and the transcriptional factors used for their reprogramming. Therefore, our study raises awareness of the need for improvements of the induction conditions of miPS cells in order to avoid the chromosomal aberrations and ensure future safe applications. PMID:22009222

Chen, Qian; Shi, Xiaoyun; Rudolph, Cornelia; Yu, Yong; Zhang, Ding; Zhao, Xiaoyu; Mai, Sabine; Wang, Gang; Schlegelberger, Brigitte; Shi, Qinghua

2011-10-19

212

Designing power supply (PS) using digital PID based on AVR microcontrollers  

Microsoft Academic Search

This paper presents a method to design a kind of power supply (PS) using PID (Proportional, Integral, and Derivative) controller. AVR microcontroller, atmega16 has been used in designing PS. Nowadays most of industrials systems use microcontrollers. PS is the integral part in each of them. A good idea is using these processors in order to generate the needed power for

Taghi. Mohamadi

2011-01-01

213

PS Integrins and Laminins: Key Regulators of Cell Migration during Drosophila Embryogenesis  

PubMed Central

During embryonic development, there are numerous cases where organ or tissue formation depends upon the migration of primordial cells. In the Drosophila embryo, the visceral mesoderm (vm) acts as a substrate for the migration of several cell populations of epithelial origin, including the endoderm, the trachea and the salivary glands. These migratory processes require both integrins and laminins. The current model is that ?PS1?PS (PS1) and/or ?PS3?PS (PS3) integrins are required in migrating cells, whereas ?PS2?PS (PS2) integrin is required in the vm, where it performs an as yet unidentified function. Here, we show that PS1 integrins are also required for the migration over the vm of cells of mesodermal origin, the caudal visceral mesoderm (CVM). These results support a model in which PS1 might have evolved to acquire the migratory function of integrins, irrespective of the origin of the tissue. This integrin function is highly specific and its specificity resides mainly in the extracellular domain. In addition, we have identified the Laminin ?1,2 trimer, as the key extracellular matrix (ECM) component regulating CVM migration. Furthermore, we show that, as it is the case in vertebrates, integrins, and specifically PS2, contributes to CVM movement by participating in the correct assembly of the ECM that serves as tracks for migration.

Urbano, Jose M.; Dominguez-Gimenez, Paloma; Estrada, Beatriz; Martin-Bermudo, Maria D.

2011-01-01

214

Evidence for intracellular partitioning of serine and glycine metabolism in Chinese hamster ovary cells.  

PubMed Central

Serine hydroxymethyltransferase (SHMT) is the primary enzyme in the interconversion of serine and glycine. The roles of mitochondrial and cytosolic SHMT in the interconversion of serine and glycine were determined in two Chinese hamster ovary (CHO) cell lines that both contain cytosolic SHMT but either have (CHOm+) or lacK (CHOm-) mitochondrial SHMT. Mitochondrial SHMT activity was significantly reduced in CHOm- (0.24 +/- 0.11 nmol/min per mg of mitochondrial protein) compared with CHOm+ (3.21 +/- 0.66 nmol/min per mg of mitochondrial protein; P = 0.02) cells, whereas cytosolic SHMT activity was similar in CHOm- and CHOm+ cells (1.09 +/- 0.31 and 1.53 +/- 0.12 nmol/min per mg of cytosolic protein respectively; P = 0.57). In CHOm+ and CHOm- cells, the relative flux of glycine to serine measured with either [1-13C]- or [2-13C]-glycine was similar (CHOm-: 538 +/- 82 nmol/24 per mg of DNA; CHOm+: 616 +/- 88 nmol/24 h per mg of DNA; P = 0.42). In contrast, the relative flux of serine to glycine measured with [1-13C]serine was low in CHOm- cells (80 +/- 28 nmol/24 h per mg of DNA) compared with CHOm+ cells (3080 +/- 320 nmol/24 h per mg of DNA; P = 0.0001). The rate of glycine production determined by [1-(13)C]glycine dilution was lower in CHOm- (1200 +/- 200 nmol/24 h per mg of DNA) than CHOm+ (10200 +/- 1800 nmol/24 h per mg of DNA; P = 0.03) cells, whereas glycine utilization was similar in the two cell lines. Serine production was similar in the two cell lines but serine utilization was lower in CHOm- (3800 +/- 1200 mu mol/24 h per mg of DNA) than CHOm+ (6600 +/- 1000 nmol/24 h per mg of DNA; P = 0.0002) cells. Increasing the serine concentration in the medium resulted in an increase in glycine production in CHOm+ but not in CHOm- cells. Intracellular studies with [1-13C]serine confirm the findings of decreased glycine production from serine. In CHO cells there is partitioning of intracellular serine and glycine metabolism. Our data support the hypothesis that mitochondrial SHMT is the primary pathway for serine into glycine interconversion.

Narkewicz, M R; Sauls, S D; Tjoa, S S; Teng, C; Fennessey, P V

1996-01-01

215

Effects of deuterium labeling at PS\\/PMMA interfaces studied with resonant soft x-ray reflectivity  

Microsoft Academic Search

The interfacial widths of PS\\/PMMA and deuterated-PS\\/PMMA bilayer interfaces were analyzed using resonant soft x-ray reflectivity (RSoXR). The PS and dPS utilized had the same molecular weight and poly-dispersity. Identical sample preparation and film thicknesses were used, respectively. The PS\\/PMMA bilayer width was consistently smaller than the dPS\\/PMMA width for a number of different thickness combinations. This is unexpected, based

H. Ade; C. Wang; S. E. Harton; B. Watts; T. Araki

2007-01-01

216

Acute D-serine treatment produces antidepressant-like effects in rodents.  

PubMed

Research suggests that dysfunctional glutamatergic signalling may contribute to depression, a debilitating mood disorder affecting millions of individuals worldwide. Ketamine, a N-methyl-D-aspartate (NMDA) receptor antagonist, exerts rapid antidepressant effects in approximately 70% of patients. Glutamate evokes the release of D-serine from astrocytes and neurons, which then acts as a co-agonist and binds at the glycine site on the NR1 subunit of NMDA receptors. Several studies have implicated glial deficits as one of the underlying facets of the neurobiology of depression. The present study tested the hypothesis that D-serine modulates behaviours related to depression. The behavioural effects of a single, acute D-serine administration were examined in several rodent tests of antidepressant-like effects, including the forced swim test (FST), the female urine sniffing test (FUST) following serotonin depletion, and the learned helplessness (LH) paradigm. D-serine significantly reduced immobility in the FST without affecting general motor function. Both D-serine and ketamine significantly rescued sexual reward-seeking deficits caused by serotonin depletion in the FUST. Finally, D-serine reversed LH behaviour, as measured by escape latency, number of escapes, and percentage of mice developing LH. Mice lacking NR1 expression in forebrain excitatory neurons exhibited a depression-like phenotype in the same behavioural tests, and did not respond to D-serine treatment. These findings suggest that D-serine produces antidepressant-like effects and support the notion of complex glutamatergic dysfunction in depression. It is unclear whether D-serine has a convergent influence on downstream synaptic plasticity cascades that may yield a similar therapeutic profile to NMDA antagonists like ketamine. PMID:21906419

Malkesman, Oz; Austin, Daniel R; Tragon, Tyson; Wang, Gang; Rompala, Gregory; Hamidi, Anahita B; Cui, Zhenzhong; Young, W Scott; Nakazawa, Kazu; Zarate, Carlos A; Manji, Husseini K; Chen, Guang

2011-09-12

217

Acute D-serine treatment produces antidepressant-like effects in rodents  

PubMed Central

Research suggests that dysfunctional glutamatergic signalling may contribute to depression, a debilitating mood disorder affecting millions of individuals worldwide. Ketamine, a N-methyl-D-aspartate (NMDA) receptor antagonist, exerts rapid antidepressant effects in approximately 70% of patients. Glutamate evokes the release of D-serine from astrocytes and neurons, which then acts as a co-agonist and binds at the glycine site on the NR1 subunit of NMDA receptors. Several studies have implicated glial deficits as one of the underlying facets of the neurobiology of depression. The present study tested the hypothesis that D-serine modulates behaviours related to depression. The behavioural effects of a single, acute D-serine administration were examined in several rodent tests of antidepressant-like effects, including the forced swim test (FST), the female urine sniffing test (FUST) following serotonin depletion, and the learned helplessness (LH) paradigm. D-serine significantly reduced immobility in the FST without affecting general motor function. Both D-serine and ketamine significantly rescued sexual reward-seeking deficits caused by serotonin depletion in the FUST. Finally, D-serine reversed LH behaviour, as measured by escape latency, number of escapes, and percentage of mice developing LH. Mice lacking NR1 expression in forebrain excitatory neurons exhibited a depression-like phenotype in the same behavioural tests, and did not respond to D-serine treatment. These findings suggest that D-serine produces antidepressant-like effects and support the notion of complex glutamatergic dysfunction in depression. It is unclear whether D-serine has a convergent influence on downstream synaptic plasticity cascades that may yield a similar therapeutic profile to NMDA antagonists like ketamine.

Malkesman, Oz; Austin, Daniel R.; Tragon, Tyson; Wang, Gang; Rompala, Gregory; Hamidi, Anahita B.; Cui, Zhenzhong; Young, W. Scott; Nakazawa, Kazu; Zarate, Carlos A.; Manji, Husseini K.; Chen, Guang

2011-01-01

218

Human iPS Cell-Based Therapy: Considerations Before Clinical Applications  

PubMed Central

Generation of induced pluripotent stem (iPS) cells has revolutionized the field of regenerative medicine. With the exponential increase in iPS cell research in the past three years, human iPS cells have been derived with different technologies and from various cell types. From a translational perspective, however, a number of issues must be addressed before safe and high quality patient-specific iPS cells can be derived for clinical applications. In addition, iPS cell-based therapies also need to be thoroughly evaluated in pre-clinical animal models before they can be applied to human subjects.

Sun, Ning; Longaker, Michael T.; Wu, Joseph C.

2013-01-01

219

Crystal Structure of Serine Racemase that Produces Neurotransmitter d-Serine for Stimulation of the NMDA Receptor  

NASA Astrophysics Data System (ADS)

d-Serine is an endogenous coagonist for the N-methyl-d-aspartate receptor and is involved in excitatory neurotransmission in the brain. Mammalian pyridoxal 5’-phosphate-dependent serine racemase, which is localized in the mammalian brain, catalyzes the racemization of l-serine to yield d-serine and vice versa. We have determined the structures of three forms of the mammalian enzyme homolog from Schizosaccharomyces pombe. Lys57 and Ser82 located on the protein and solvent sides, respectively, with respect to the cofactor plane, are acid-base catalysts that shuttle protons to the substrate. The modified enzyme, which has a unique lysino-d-alanyl residue at the active site, also binds the substrate serine in the active site, suggesting that the lysino-d-alanyl residue acts as a catalytic base in the same manner as Lys57 of the wild type enzyme.

Goto, Masaru

220

Rapid Development of a Potent Photo-Triggered Inhibitor of the Serine Hydrolase RBBP9  

PubMed Central

The serine hydrolases constitute a large class of enzymes that play important roles in physiology. There is great interest in the development of potent and selective pharmacological inhibitors to these proteins. Traditional active site inhibitors often have limited selectivity within this superfamily and are tedious and expensive to discover. Using the serine hydrolase RBBP9 as a model target, we report here a rapid and relatively inexpensive route to highly selective peptoid-based inhibitors that can be activated with visible light. This technology provides rapid access to photo-activated tool compounds capable of selectively blocking the function of particular serine hydrolases.

Liu, Xiaodan; Dix, Melissa; Speers, Anna E.; Bachovchin, Daniel A.; Zuhl, Andrea M.

2013-01-01

221

[Algal toxins, inhibitors of serine/threonine phosphatases].  

PubMed

Under certain environmental conditions, marine and freshwater phytoplankton may produce phycotoxins inhibitors of serine/thréonine protein phosphatases 1, 2A and 3. In the marine environment, dinoflagellates produce fatty polyethers: okadaic acid and its derivatives, the dinophysistoxins, which accumulate in shellfish and can cause diarrhetic shellfish poisoning (DSP) when ingested. In freshwater, the toxins are microcystins and nodularin, 7 or 5 amino acid cyclic peptides and are hepatotoxic. These toxins have caused massive poisoning of wild animals or domestic livestock and now are a health threat for humans through use of drinking and recreation water. Moreover, all these toxins are potent tumor promoters but belong to a new class, different from the TPA class, because they do not act on Protein Kinase C. Although the mutagenicity Ames test responds negatively, several results show their genotoxic potential, and therefore they are a health hazard through chronic exposition to low doses. Finally, okadaic acid, through its easy penetration in all cellular types can be used as a tool to study mechanisms involved in protein phosphorylation/dephosphorylation processes. PMID:9759380

Huynh-Delerme, C; Puiseux-Dao, S

1998-01-01

222

Stromal serine protein kinase activity in spinach chloroplasts  

SciTech Connect

At least twelve /sup 32/P-labeled stromal proteins were detected by electrophoresis under denaturing conditions when intact chloroplasts were incubated with /sup 32/Pi, in the light but only three were detected in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) or in the dark. Incubation of isolated stroma with (gamma-/sup 32/P)ATP resulted in the preferential phosphorylation of one of them, a 70-kDa polypeptide, in serine residues. Thylakoid membranes in the dark promoted the phosphorylation of two additional stromal polypeptides of 55 and 40 kDa. Illumination during the phosphorylation of stroma in the presence of thylakoids stimulated severalfold the labeling of the 40-kDa polypeptide but not when DCMU was added. The protein kinase activity present in isolated stroma phosphorylated exogenous substrates like histone III, phosvitin, histone II, and casein with specific activities of 3, 1.8, 0.7, and 0.2 pmol X mg-1 X min-1. Histone III polypeptides were phosphorylated differently by stroma and by thylakoids in the dark. Moreover, histone III phosphorylated by thylakoids in the dark yielded a pattern of phosphopeptides after V8 protease treatment that was different from the pattern obtained when histone III was phosphorylated by stroma.

Cortez, N.; Lucero, H.A.; Vallejos, R.H.

1987-05-01

223

Pramipexole Reduces Phosphorylation of ?-Synuclein at Serine-129.  

PubMed

?-Synuclein is a central component of the pathogenesis of Parkinson's disease (PD). Phosphorylation at serine-129 represents an important post-translational modification and constitutes the major form of the protein in Lewy bodies. Several kinases have been implicated in the phosphorylation of ?-synuclein. The targeting of kinase pathways as a potential to influence the pathogenesis of PD is an important focus of attention, given that mutations of specific kinases (LRRK2 and PINK1) are causes of familial PD. Pramipexole (PPX) is a dopamine agonist developed for the symptomatic relief of PD. Several in vitro and in vivo laboratory studies have demonstrated that PPX exerts neuroprotective properties in model systems of relevance to PD. The present study demonstrates that PPX inhibits the phosphorylation of ?-synuclein and that this is independent of dopamine receptor activation. PPX blocks the increase in phosphorylated ?-synuclein induced by inhibition of the ubiquitin proteasomal system. The phosphorylation of ?-synuclein occurs in part at least through casein kinase 2, and PPX in turn reduces the phosphorylation of this enzyme, thereby inhibiting its activity. Thus, PPX decreases the phosphorylation of ?-synuclein, and this mechanism may contribute to its protective properties in PD models. PMID:23681749

Chau, Kai-Yin; Cooper, J Mark; Schapira, Anthony Henry V

2013-05-18

224

Phosphorylation at serine 331 is required for Aurora B activation  

PubMed Central

Aurora B kinase activity is required for successful cell division. In this paper, we show that Aurora B is phosphorylated at serine 331 (Ser331) during mitosis and that phosphorylated Aurora B localizes to kinetochores in prometaphase cells. Chk1 kinase is essential for Ser331 phosphorylation during unperturbed prometaphase or during spindle disruption by taxol but not nocodazole. Phosphorylation at Ser331 is required for optimal phosphorylation of INCENP at TSS residues, for Survivin association with the chromosomal passenger complex, and for complete Aurora B activation, but it is dispensable for Aurora B localization to centromeres, for autophosphorylation at threonine 232, and for association with INCENP. Overexpression of Aurora BS331A, in which Ser331 is mutated to alanine, results in spontaneous chromosome missegregation, cell multinucleation, unstable binding of BubR1 to kinetochores, and impaired mitotic delay in the presence of taxol. We propose that Chk1 phosphorylates Aurora B at Ser331 to fully induce Aurora B kinase activity. These results indicate that phosphorylation at Ser331 is an essential mechanism for Aurora B activation.

Petsalaki, Eleni; Akoumianaki, Tonia; Black, Elizabeth J.; Gillespie, David A.F.

2011-01-01

225

Homologous inhibitors from potato tubers of serine endopeptidases and metallocarboxypeptidases.  

PubMed Central

A potent polypeptide inhibitor of chymotrypsin has been purified from Russett Burbank potatoes. The inhibitor has no effect on bovine carboxypeptidases A or B but exhibits homology with a carboxypeptidase inhibitor that is also present in potato tubers. The chymotrypsin inhibitor has a molecular weight of approximately 5400 as estimated by gel filtration, amino acid analysis, and titration with chymotrypsin. The polypeptide chain consists of 49 amino acid residues, of which six are half-cystine, forming three disulfide bonds. Its size is similar to that of the carboxypeptidase inhibitor, which contains 39 amino acid residues and also has three disulfide bridges. In immunological double diffusion assays, the chymotrypsin inhibitor and the carboxypeptidase inhibitor do not crossreact; however, automatic Edman degradation of reduced and alkylated derivatives of the chymotrypsin inhibitor, yielding a partial sequence of 18 amino acid residues at the NH2-terminus, reveals a similarity in sequence to that of the carboxypeptidase inhibitor. Thus, inhibitors directed toward two distinct classes of proteases, the serine endopeptidases and the metallocarboxypeptidases, appear to have evolved from a common ancestor. Images

Hass, C M; Venkatakrishnan, R; Ryan, C A

1976-01-01

226

Regulation of Adrenal Aldosterone Production by Serine Protease Prostasin  

PubMed Central

A serine protease prostasin has been demonstrated to have a pivotal role in the activation of the epithelial sodium channel. Systemic administration of adenovirus carrying human prostasin gene in rats resulted in an increase in plasma prostasin and aldosterone levels. However, the mechanism by which the elevation of prostasin levels in the systemic circulation stimulated the plasma aldosterone levels remains unknown. Therefore, we examined if prostasin increases the aldosterone synthesis in a human adrenocortical cell line (H295R cells). Luciferase assay using CYP11B2 promoter revealed that prostasin significantly increased the transcriptional activity of CYP11B2. Prostasin significantly increased both CYP11B2 mRNA expression and aldosterone production in a dose-dependent manner. Surprisingly, treatment with camostat mesilate, a potent prostasin inhibitor, had no effect on the aldosterone synthesis by prostasin and also a protease-dead mutant of prostasin significantly stimulated the aldosterone production. A T-type/L-type calcium channel blocker and a protein kinase C (PKC) inhibitor significantly reduced the aldosterone synthesis by prostasin. Our findings suggest a stimulatory effect of prostasin on the aldosterone synthesis by adrenal gland through the nonproteolytic action and indicate a new role of prostasin in the systemic circulation.

Ko, Takehiro; Kakizoe, Yutaka; Wakida, Naoki; Hayata, Manabu; Uchimura, Kohei; Shiraishi, Naoki; Miyoshi, Taku; Adachi, Masataka; Aritomi, Shizuka; Konda, Tomoyuki; Tomita, Kimio; Kitamura, Kenichiro

2010-01-01

227

Radio observations of PS1-12fo (=CSS120121)  

NASA Astrophysics Data System (ADS)

PS1-12fo is an ultra-luminous supernova of Type Ic at z=0.175 (ATel #3918), belonging to the SN class identified by Quimby et al. (2011, Nature, 474, 487). We searched for radio continuum emission from this SN with the EVLA on 2012 Feb 12.3 UT at a frequency of 5.9 GHz, yielding a non-detection of 2 ± 7 microJy. This is consistent with the non-detection of radio emission from other objects in this class (Chomiuk et al.

Chomiuk, L.; Soderberg, A.; Margutti, R.; Berger, E.; Milisavljevic, D.; Sanders, N.

2012-02-01

228

Combustion of PMMA, PE, and PS in a ramjet  

SciTech Connect

This paper reports the combustion behavior of polymethylmetharcrylate (PMMA), polyethylene (PE), and polystyrene (PS) with air investigated in a connected pipe test facility; spectroscopy showed the presence of OH, C{sub 2}, and CH and temperatures between 1300 and 3000 K during combustion. Particular attention was focused on regression rate and combustion efficiency and the role of temperature and soot production. The present investigation gives an understanding of the most important phenomena that control (or emanate from) the combustion of a cylindrical solid fuel with a rearward facing step, and this has application for solid fuel ramjets, the safe burning of toxic waste, and hot gas generators. The results are summarized.

van der Geld, C.W.M. (Eindhoven University of Technology, Faculty of Mechanical Engineering, 5600 MB Eindhoven (NL)); Korting, P.A.O.G. (Prins Maurits Lab. TNO, Rijswijk (Netherlands)); Wijchers, T. (Delft University of Technology (NL))

1990-03-01

229

Interactome analyses of mature ?-secretase complexes reveal distinct molecular environments of presenilin (PS) paralogs and preferential binding of signal peptide peptidase to PS2.  

PubMed

?-Secretase plays a pivotal role in the production of neurotoxic amyloid ?-peptides (A?) in Alzheimer disease (AD) and consists of a heterotetrameric core complex that includes the aspartyl intramembrane protease presenilin (PS). The human genome codes for two presenilin paralogs. To understand the causes for distinct phenotypes of PS paralog-deficient mice and elucidate whether PS mutations associated with early-onset AD affect the molecular environment of mature ?-secretase complexes, quantitative interactome comparisons were undertaken. Brains of mice engineered to express wild-type or mutant PS1, or HEK293 cells stably expressing PS paralogs with N-terminal tandem-affinity purification tags served as biological source materials. The analyses revealed novel interactions of the ?-secretase core complex with a molecular machinery that targets and fuses synaptic vesicles to cellular membranes and with the H(+)-transporting lysosomal ATPase macrocomplex but uncovered no differences in the interactomes of wild-type and mutant PS1. The catenin/cadherin network was almost exclusively found associated with PS1. Another intramembrane protease, signal peptide peptidase, predominantly co-purified with PS2-containing ?-secretase complexes and was observed to influence A? production. PMID:23589300

Jeon, Amy Hye Won; Böhm, Christopher; Chen, Fusheng; Huo, Hairu; Ruan, Xueying; Ren, Carl He; Ho, Keith; Qamar, Seema; Mathews, Paul M; Fraser, Paul E; Mount, Howard T J; St George-Hyslop, Peter; Schmitt-Ulms, Gerold

2013-04-15

230

The elite and stochastic model for iPS cell generation: multilineage-differentiating stress enduring (Muse) cells are readily reprogrammable into iPS cells.  

PubMed

Induced pluripotent stem (iPS) cells have attracted a great deal of attention, although the mechanism by which they are generated is still not fully understood. Currently, two theories, the stochastic and elite models, have been proposed. Some reports provide theoretical support for the stochastic model. Other reports, however, support the elite model. For example, some human fibroblasts, such as Multilineage-differentiating stress enduring (Muse) cells, are reported to be pluripotent and a primary source of iPS cells. Thus, the mechanism of iPS cell generation continues to be debated. In this review, we discuss the properties of the original cell source, such as the components of the original populations and the potential of each population to become iPS cells, and further discuss the implications of the two theories for iPS cell research. PMID:22693162

Wakao, Shohei; Kitada, Masaaki; Dezawa, Mari

2012-06-12

231

Small Molecule Activation of PKM2 in Cancer Cells Induces Serine Auxotrophy  

PubMed Central

SUMMARY Proliferating tumor cells use aerobic glycolysis to support their high metabolic demands. Paradoxically, increased glycolysis is often accompanied by expression of the lower activity PKM2 isoform, effectively constraining lower glycolysis. Here, we report the discovery of PKM2 activators with a unique allosteric binding mode. Characterization of how these compounds impact cancer cells revealed an unanticipated link between glucose and amino acid metabolism. PKM2 activation resulted in a metabolic rewiring of cancer cells manifested by a profound dependency on the nonessential amino acid serine for continued cell proliferation. Induction of serine auxotrophy by PKM2 activation was accompanied by reduced carbon flow into the serine biosynthetic pathway and increased expression of high affinity serine transporters. These data support the hypothesis that PKM2 expression confers metabolic flexibility to cancer cells that allows adaptation to nutrient stress.

Kung, Charles; Hixon, Jeff; Choe, Sung; Marks, Kevin; Gross, Stefan; Murphy, Erin; DeLaBarre, Byron; Cianchetta, Giovanni; Sethumadhavan, Shalini; Wang, Xiling; Yan, Shunqi; Gao, Yi; Fang, Cheng; Wei, Wentao; Jiang, Fan; Wang, Shaohui; Qian, Kevin; Saunders, Jeff; Driggers, Ed; Woo, Hin Koon; Kunii, Kaiko; Murray, Stuart; Yang, Hua; Yen, Katharine; Liu, Wei; Cantley, Lewis C.; Vander Heiden, Matthew G.; Su, Shinsan M.; Jin, Shengfang; Salituro, Francesco G.; Dang, Lenny

2013-01-01

232

Occurrence of Type S1A Serine Proteases in Sponge and Jellyfish.  

National Technical Information Service (NTIS)

Although serine proteases are found in all kinds of cellular organisms and many viruses, the classic 'chymotrypsin family' (Group S1A by the 1998 Barrett nomenclature) has an unusual phylogenetic distribution, being especially common in animals, entirely ...

A. Rojas R. F. Doolittle

2003-01-01

233

A novel transmembrane serine protease (TMPRSS3) overexpressed in pancreatic cancer.  

PubMed

We report the characterization of a novel serine protease of the chymotrypsin family, recently isolated by cDNA-representational difference analysis, as a gene overexpressed in pancreatic cancer. The 2.3-kb mRNA of the gene, named TMPRSS3, is strongly expressed in a subset of pancreatic cancer and various other cancer tissues, and its expression correlates with the metastatic potential of the clonal SUIT-2 pancreatic cancer cell lines. The deduced polypeptide sequence consists of 437 amino acids and exhibits all of the structural features characteristic of serine proteases with trypsin-like activity. TMPRSS3 is membrane bound with a NH2-terminal signal-anchor sequence and a glycosylated extracellular region containing the serine protease domain. Thus, TMPRSS3 is a novel membrane-bound serine protease overexpressed in cancer, which may be of importance for processes involved in metastasis formation and tumor invasion. PMID:10825129

Wallrapp, C; Hähnel, S; Müller-Pillasch, F; Burghardt, B; Iwamura, T; Ruthenbürger, M; Lerch, M M; Adler, G; Gress, T M

2000-05-15

234

An Evening Sector Ps 6 - Omega Band Event  

NASA Astrophysics Data System (ADS)

Ps 6 magnetic disturbances and associated optical forms known as omega bands are usually associated with the morning sector. The positive Y and transitional Z perturbations of the Ps 6 signal indicate localized regions of equatorward equivalent current in the auroral ionosphere, associated with the bright and vortical forms of the omega bands. The currents and optical forms drift sunward (eastward) at speeds typical of bulk convection. Evidence for similar phenomenology in the evening sector has been presented by Solovyev et al. (JGR 104, 28019, 1999). We confirm and enhance these results by presenting early results from the new Athabasca University Geophysical Observatory from July 27, 2003. These are magnetic perturbations from the UCLA magnetometer, and high time resolution optical imaging of associated omega bands from the all sky imager, which together make a prototype ground based networked observatory for the NASA THEMIS MIDEX mission. The signatures drift sunward (westward) and the magnetic perturbations feature negative Y and transitional Z indicating passage of poleward equivalent currents overhead. These results suggest that Kelvin-Helmholtz instablilities, the likely cause of the morning sector features, can also excite waves in the evening sector under appropriate circumstances.

Connors, M.; Donovan, E. F.; Syrjaesuo, M.; Greffen, M.; Mende, S. B.; Russell, C. T.; Jackel, B. J.; Trondsen, T.

2003-12-01

235

Human hair follicle pluripotent stem (hfPS) cells promote regeneration of peripheral-nerve injury: an advantageous alternative to ES and iPS cells.  

PubMed

The optimal source of stem cells for regenerative medicine is a major question. Embryonic stem (ES) cells have shown promise for pluripotency but have ethical issues and potential to form teratomas. Pluripotent stem cells have been produced from skin cells by either viral-, plasmid- or transposon-mediated gene transfer. These stem cells have been termed induced pluripotent stem cells or iPS cells. iPS cells may also have malignant potential and are inefficiently produced. Embryonic stem cells may not be suited for individualized therapy, since they can undergo immunologic rejection. To address these fundamental problems, our group is developing hair follicle pluripotent stem (hfPS) cells. Our previous studies have shown that mouse hfPS cells can differentiate to neurons, glial cells in vitro, and other cell types, and can promote nerve and spinal cord regeneration in vivo. hfPS cells are located above the hair follicle bulge in what we have termed the hfPS cell area (hfPSA) and are nestin positive and keratin 15 (K-15) negative. Human hfPS cells can also differentiate into neurons, glia, keratinocytes, smooth muscle cells, and melanocytes in vitro. In the present study, human hfPS cells were transplanted in the severed sciatic nerve of the mouse where they differentiated into glial fibrillary-acidic-protein (GFAP)-positive Schwann cells and promoted the recovery of pre-existing axons, leading to nerve generation. The regenerated nerve recovered function and, upon electrical stimulation, contracted the gastrocnemius muscle. The hfPS cells can be readily isolated from the human scalp, thereby providing an accessible, autologous and safe source of stem cells for regenerative medicine that have important advantages over ES or iPS cells. PMID:19507228

Amoh, Yasuyuki; Kanoh, Maho; Niiyama, Shiro; Hamada, Yuko; Kawahara, Katsumasa; Sato, Yuichi; Hoffman, Robert M; Katsuoka, Kensei

2009-08-01

236

Purification and characterization of an extracellular serine protease from the nematode-trapping fungus Dactylella shizishanna  

Microsoft Academic Search

Aims: To evaluate the production of an extracellular serine protease by Dactyl- ella shizishanna and its potential as a pathogenesis factor. Methods and Results: An extracellular alkaline serine protease (Ds1) was puri- fied and characterized from the nematode-trapping fungus D. shizishanna using cation-exchange chromatography and hydrophobic interaction chromatography. The molecular mass of the protease was approximately 35 kDa estimated by

R. B. Wang; J. K. Yang; C. Lin; Y. Zhang; K. Q. Zhang

2006-01-01

237

Serine dehydratase expression decreases in rat livers injured by chronic thioacetamide ingestion  

Microsoft Academic Search

Serine dehydratase (SerDH) is a gluconeogenic enzyme involved in the catabolism of serine, which is regulated by the composition of their diet and their hormonal status in rats. This study examines how chronic injury caused to the liver of rats by the ingestion of thioacetamide (TAA) affects SerDH protein, mRNA levels, enzyme kinetics and its tissue location. After 97 days’

Inmaculada López-Flores; Juan B. Barroso; Raquel Valderrama; Francisco J. Esteban; Esther Martínez-Lara; Francisco Luque; M. Ángeles Peinado; Hirofumi Ogawa; José A. Lupiáñez; Juan Peragón

2005-01-01

238

Serine proteinase from Bacillus brevis : lytic action on intact yeast cells  

Microsoft Academic Search

A serine proteinase which showed lytic acitivity against either intact cell or cell wall preparations of Candida utilis has been isolated from Bacillus brevis culture filtrate by affinity chromatography on bacitracin-silochrome and phenylboronale-Sepharose. Both its proteolytic and lytic activities were completely abolished by inhibitors of serine proteinases, including phenylmethylsul-phonylfluoride, the inhibitor from Actinomyces janthinus, and duck ovomucoid. The optimum pH

Tatyana S. Kalebina; Galina N. Rudenskaya; Irina O. Selyakh; Olga M. Khodova; Galina G. Chestukhina; Valentin M. Stepanov; Igor S. Kulaev

1988-01-01

239

Glutamate and serine as competing donors for amination of glyoxylate in leaf peroxisomes  

Microsoft Academic Search

When provided with glycollate, peroxisomal extracts of leaves of spinach beet (Beta vulgaris L. cv.) converted L-serine and L-glutamate to hydroxypyruvate and 2-oxoglutarate respectively. When approximately saturating concentrations of each of these amino acids were incubated separately with glycollate, the utilization of serine was greater than that of glutamate. The utilization of glutamate was substantially reduced by the presence of

Nicholas J. Walton; Vernon S. Butt

1981-01-01

240

A secreted serine protease of Paracoccidioides brasiliensis and its interactions with fungal proteins  

Microsoft Academic Search

BACKGROUND: Paracoccidioides brasiliensis is a thermodimorphic fungus, the causative agent of paracoccidioidomycosis (PCM). Serine proteases are widely distributed and this class of peptidase has been related to pathogenesis and nitrogen starvation in pathogenic fungi. RESULTS: A cDNA (Pbsp) encoding a secreted serine protease (PbSP), was isolated from a cDNA library constructed with RNAs of fungal yeast cells recovered from liver

Juliana A Parente; Sílvia M Salem-Izacc; Jaime M Santana; Maristela Pereira; Clayton L Borges; Alexandre M Bailão; Célia MA Soares

2010-01-01

241

Light-induced D1 protein degradation is catalyzed by a serine-type protease.  

PubMed

Light-induced degradation of the D1 protein in isolated spinach photosystem II core preparations was studied after addition of various protease inhibitors. The degradation was selectively inhibited by several serine protease inhibitors in particular diisopropylfluorophosphate. The results demonstrate that the D1 protein is degraded by a serine-type of proteolytic activity that is an integral part of photosystem II. PMID:1715282

Virgin, I; Salter, A H; Ghanotakis, D F; Andersson, B

1991-08-01

242

Purification and Characterization of Serine Racemase from a Hyperthermophilic Archaeon, Pyrobaculum islandicum? †  

PubMed Central

Pyrobaculum islandicum is an anaerobic hyperthermophilic archaeon that is most active at 100°C. A pyridoxal 5?-phosphate-dependent serine racemase called Srr was purified from the organism. The corresponding srr gene was cloned, and recombinant Srr was purified from Escherichia coli. It showed the highest racemase activity toward l-serine, followed by l-threonine, d-serine, and d-threonine. Like rodent and plant serine racemases, Srr is bifunctional, showing high l-serine/l-threonine dehydratase activity. The sequence of Srr is 87% similar to that of Pyrobaculum aerophilum IlvA (a putative threonine dehydratase) but less than 32% similar to any other serine racemases and threonine dehydratases. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration analyses revealed that Srr is a homotrimer of a 44,000-molecular-weight subunit. Both racemase and dehydratase activities were highest at 95°C, while racemization and dehydration were maximum at pH 8.2 and 7.8, respectively. Unlike other, related Ilv enzymes, Srr showed no allosteric properties: neither of these enzymatic activities was affected by either l-amino acids (isoleucine and valine) or most of the metal ions. Only Fe2+ and Cu2+ caused 20 to 30% inhibition and 30 to 40% stimulation of both enzyme activities, respectively. ATP inhibited racemase activity by 10 to 20%. The Km and Vmax values of the racemase activity of Srr for l-serine were 185 mM and 20.1 ?mol/min/mg, respectively, while the corresponding values of the dehydratase activity of l-serine were 2.2 mM and 80.4 ?mol/min/mg, respectively.

Ohnishi, Masato; Saito, Makoto; Wakabayashi, Sadao; Ishizuka, Morio; Nishimura, Katsushi; Nagata, Yoko; Kasai, Sabu

2008-01-01

243

Regulation of BAD phosphorylation at serine 112 by the Ras-mitogen-activated protein kinase pathway  

Microsoft Academic Search

The function of the pro-apoptotic molecule BAD is regulated by phosphorylation of two sites, serine-112 (Ser-112) and serine-136 (Ser-136). Phosphorylation at either site results in loss of the ability of BAD to heterodimerize with the survival proteins BCL-XL or BCL-2. Phosphorylated BAD binds to 14-3-3 and is sequestered in the cytoplasm. It has been shown that phosphorylation of BAD at

Xianjun Fang; Shuangxing Yu; Astrid Eder; Muling Mao; Robert C Bast; Douglas Boyd; Gordon B Mills

1999-01-01

244

Sequence of the gene encoding an alkaline serine protease of thermophilic Bacillus smithii.  

PubMed

The complete nucleotide sequence of the gene encoding an alkaline serine protease from Bacillus smithii has been determined. Degenerate oligodeoxyribonucleotide primers were used to prime the amplification of a 507-bp sequence of the gene. This sequence was successively used for constructing new primers applied in inverse polymerase chain reaction, using as template self-ligated DNA fragments. The deduced amino-acid sequence is compared to serine proteases from B. amyloliquefaciens, B. licheniformis, B. subtilis and Thermus aquaticus. PMID:8045417

Milano, A; Manachini, P L; Parini, C; Riccardi, G

1994-07-22

245

Glia-Derived d-Serine Controls NMDA Receptor Activity and Synaptic Memory  

Microsoft Academic Search

SUMMARY The NMDA receptor is a key player in excitatory transmission and synaptic plasticity in the cen- tral nervous system. Its activation requires the binding of both glutamate and a coagonist like D-serine to its glycine site. As D-serine is re- leased exclusively by astrocytes, we studied the physiological impact of the glial environ- ment on NMDA receptor-dependent activity and

Aude Panatier; Dionysia T. Theodosis; Jean-Pierre Mothet; Bastien Touquet; Loredano Pollegioni; Dominique A. Poulain; Stéphane H. R. Oliet

2006-01-01

246

Glycine consumption and mitochondrial serine hydroxymethyltransferase in cancer cells: the heme connection.  

PubMed

It was recently discovered that glycine consumption is strongly related to the rate of proliferation across cancer cells. This is very intriguing and raises the question of what is the actual role of this amino acid in cancer metabolism. Cancer cells are greedy for glycine. In particular, the mitochondrial production of glycine seems to be utterly important. Overexpression of mitochondrial serine hydroxymethyltransferase, the enzyme converting l-serine to glycine, assures an adequate supply of glycine to rapidly proliferating cancer cells. In fact, silencing of mitochondrial serine hydroxymethyltransferase was shown to halt cancer cell proliferation. Direct incorporation of glycine carbon atoms into the purine ring has been proposed to be one main reason for the importance of glycine in cancer cell metabolism. We believe that, as far as the importance of glycine in cancer is concerned, a central role of this amino acid, namely its participation to heme biosynthesis, has been neglected. In mitochondria, glycine condenses with succinyl-CoA to form 5-aminolevulinate, the universal precursor of the different forms of heme contained in cytochromes and oxidative phosphorylation complexes. Our hypothesis is that mitochondrial serine hydroxymethyltransferase is fundamental to sustain cancer metabolism since production of glycine fuels heme biosynthesis and therefore oxidative phosphorylation. Respiration of cancer cells may then ultimately rely on endogenous glycine synthesis by mitochondrial serine hydroxymethyltransferase. The link between mitochondrial serine hydroxymethyltransferase activity and heme biosynthesis represents an important and still unexplored aspect of the whole picture of cancer cell metabolism. Our hypothesis might be tested using a combination of metabolic tracing and gene silencing on different cancer cell lines. The experiments should be devised so as to assess the importance of mitochondrial serine hydroxymethyltransferase and the glycine deriving from its reaction as a precursor of heme. If the observed increase of glycine consumption in rapidly proliferating cancer cells has its basis in the need for heme biosynthesis, then mitochondrial serine hydroxymethyltransferase should be considered as a key target for the development of new chemotherapeutic agents. PMID:23474074

di Salvo, Martino L; Contestabile, Roberto; Paiardini, Alessandro; Maras, Bruno

2013-03-06

247

Identification and characterization of a serine protease inhibitor of Clonorchis sinensis  

Microsoft Academic Search

A gene encoding a serine protease inhibitor of Clonorchis sinensis (CsSERPIN) was identified and characterized. CsSERPIN contained an open reading frame of 1158bp that encoded 385 amino acid residues. Sequence analysis of the primary structure of CsSERPIN revealed that it had essential structural motifs including a reactive central loop (RCL), which well conserved in the serine protease inhibitor (serpin) superfamily.

Jung-Mi Kang; Woon-Mok Sohn; Jung-Won Ju; Tong-Soo Kim; Byoung-Kuk Na

2010-01-01

248

Plasmodium serine hydroxymethyltransferase: indispensability and display of distinct localization  

PubMed Central

Background Serine hydroxymethyltransferase (SHMT), a pyridoxal phosphate-dependent enzyme, plays a vital role in the de novo pyrimidine biosynthesis pathway in malaria parasites. Two genes have been identified in Plasmodium spp. encoding a cytosolic SHMT (cSHMT) and putative mitochondria SHMT (mSHMT), but their roles have not been fully investigated. Methods The presence of Plasmodium SHMT isoforms in the intra-erythrocytic stage was assessed based on their gene expression using reverse transcription PCR (RT-PCR). Localization studies of Plasmodium SHMT isoforms were performed by transfection of fluorescent-tagged gene constructs into P. falciparum and expressions of fluorescent fusion proteins in parasites were observed using a laser scanning confocal microscope. Genetic targeting through homologous recombination was used to study the essentiality of SHMT in Plasmodium spp. Results Semi-quantitative RT-PCR revealed the expression of these two genes throughout intra-erythrocytic development. Localization studies using P. falciparum expressing fluorescent-tagged SHMT showed that PfcSHMT-red fluorescent fusion protein (PfcSHMT-DsRed) is localized in the cytoplasm, while PfmSHMT-green fluorescent fusion protein (PfmSHMT-GFP) co-localized with Mitotracker™-labelled mitochondria as predicted. The essentiality of plasmodial cSHMT was inferred from transfection experiments where recovery of viable knock-out parasites was not achieved, unless complemented with a functional equivalent copy of shmt. Conclusions Distinct compartment localizations of PfSHMT were observed between cytoplasmic and mitochondrial isoforms, and evidence was provided for the indispensable role of plasmodial cSHMT indicating it as a valid target for development of novel anti-malarials.

2012-01-01

249

Covalent Inhibition of Serine ?-Lactamases by Novel Hydroxamic Acid Derivatives.  

PubMed

The effectiveness of ?-lactam antibiotics is greatly limited by the ability of bacteria to produce ?-lactamases. These enzymes catalyze the hydrolysis of ?-lactams and thus loss of their antibiotic activity. The search for inhibitors of ?-lactamases began soon after ?-lactams were introduced into medical practice and continues today. Some time ago, we introduced a new class of covalent serine ?-lactamase inhibitors, the O-aryloxycarbonyl hydroxamates, that inactivated these enzymes by a unique mechanism in which the active site became cross-linked. We describe in this paper some new variants of this class of inhibitor. First, we investigated compounds in which more polar hydroxamates were incorporated. These were generally not more active than the original compounds against representative class A and class C ?-lactamases, but one of them, 1-(benzoyl)-O-(phenoxycarbonyl)-3-hydroxyurea, was significantly more stable in solution, thus revealing a useful platform for further design. Second, we describe a series of O-(arylphosphoryl) hydroxamates that are also irreversible inactivators of class A and class C ?-lactamases, by phosphorylation of the enzyme, as revealed by mass spectra. These compounds did not, however, cross-link the enzyme active site. A striking feature of their structure-activity profile was that hydroxamate remained the leaving group on enzyme phosphorylation rather than aryloxide, even though the aryloxide was intrinsically the better leaving group, as indicated by pKa values and demonstrated by the products of hydrolysis in free solution. Model building suggested that this phenomenon arises from the relative affinity of the enzyme active site components for the two leaving groups. The results obtained for both groups of inhibitors are important for further optimization of these inhibitors. PMID:23679223

Tilvawala, Ronak; Pratt, R F

2013-05-16

250

Structural Mechanisms of Inactivation in Scabies Mite Serine Protease Paralogues  

SciTech Connect

The scabies mite (Sarcoptes scabiei) is a parasite responsible for major morbidity in disadvantaged communities and immuno-compromised patients worldwide. In addition to the physical discomfort caused by the disease, scabies infestations facilitate infection by Streptococcal species via skin lesions, resulting in a high prevalence of rheumatic fever/heart disease in affected communities. The scabies mite produces 33 proteins that are closely related to those in the dust mite group 3 allergen and belong to the S1-like protease family (chymotrypsin-like). However, all but one of these molecules contain mutations in the conserved active-site catalytic triad that are predicted to render them catalytically inactive. These molecules are thus termed scabies mite inactivated protease paralogues (SMIPPs). The precise function of SMIPPs is unclear; however, it has been suggested that these proteins might function by binding and protecting target substrates from cleavage by host immune proteases, thus preventing the host from mounting an effective immune challenge. In order to begin to understand the structural basis for SMIPP function, we solved the crystal structures of SMIPP-S-I1 and SMIPP-S-D1 at 1.85 {angstrom} and 2.0 {angstrom} resolution, respectively. Both structures adopt the characteristic serine protease fold, albeit with large structural variations over much of the molecule. In both structures, mutations in the catalytic triad together with occlusion of the S1 subsite by a conserved Tyr200 residue is predicted to block substrate ingress. Accordingly, we show that both proteases lack catalytic function. Attempts to restore function (via site-directed mutagenesis of catalytic residues as well as Tyr200) were unsuccessful. Taken together, these data suggest that SMIPPs have lost the ability to bind substrates in a classical 'canonical' fashion, and instead have evolved alternative functions in the lifecycle of the scabies mite.

Fischer, Katja; Langendorf, Christopher G.; Irving, James A.; Reynolds, Simone; Willis, Charlene; Beckham, Simone; Law, Ruby H.P.; Yang, Sundy; Bashtannyk-Puhalovich, Tanya A.; McGowan, Sheena; Whisstock, James C.; Pike, Robert N.; Kemp, David J.; Buckle, Ashley M.; (Monash); (Queensland Inst. of Med. Rsrch.)

2009-08-07

251

Novel serine protease dipeptidyl peptidase IV inhibitor: alogliptin.  

PubMed

Alogliptin (codenamed SYR-322) is a recently approved anti-diabetic drug in Japan, which has been under clinical development phase III in USA and Europe. Alogliptin has been developed by Takeda under the brand name "Nesina". Alogliptin is a highly selective ( > 10,000-time selectivity, potent, reversible and durable serine protease dipeptidyl peptidase IV enzyme is compared to DPP-8 and DPP-9) inhibitor, which has been developed as an alternative second-line to metformin in place of a sulphonylurea. Alogliptin has been observed to increase and prolong the action of incretin hormone by inhibiting the DPP-IV enzyme activity. Alogliptin has been observed to well absorb and show low plasma protein binding, which displays slow-binding properties to DPP-IV enzyme. The X-ray crystallography studies have been revealed that Alogliptin binds to DPP-IV active site by non-covalently and provides sustained reduction of plasma DPP-IV activity as well as lowering of blood glucose, in drug-naive patients with T2DM and inadequate glycemic control, once daily oral dosing regimen with varying levels of doses ranging from 25-800 mg. Alogliptin is approved as monotherapy and in combination with alpha-glucosidase & thiazolidinediones. The 26 week clinical study of Alogliptin revealed that Alogliptin doesn't increase the weight and well tolerated. In the present review, we have tried to cover biology of DPP-IV, molecular chemistry, chemical characterization, crystal polymorphic information, interaction studies, commercial synthesis, current patent status, adverse effects and clinical status of Alogliptin giving emphasis on the medicinal chemistry aspect. PMID:22512582

Agrawal, Ritesh; Bahare, Radhe Shyam; Jain, Pratima; Dikshit, Subodh Narayan; Ganguly, Swastika

2012-11-01

252

Structural Characterization of Phosphatidyl-myo-inositol Mannosides from Mycobacterium bovis Bacillus Calmette Gu?rin by Multiple-Stage Quadrupole Ion-Trap Mass Spectrometry with Electrospray Ionization. I. PIMs and Lyso-PIMs  

PubMed Central

We described a multiple-stage ion-trap mass spectrometric approach to characterize the structures of phosphatidylinositol and phosphatidyl-myoinositol mannosides (PIMs) in a complex mixture isolated from Mycobacterium bovis Bacillus Calmette Guérin. The positions of the fatty acyl substituents of PIMs at the glycerol backbone can be easily assigned, based on the findings that the ions arising from losses of the fatty acid substituent at sn-2 as molecules of acid and of ketene, respectively (that is, the [M – H – R2CO2H]? and [M – H – R2CH=CO]? ions), are respectively more abundant than the ions arising from the analogous losses at sn-1 (that is, the [M – H – R1CO2H]? and [M – H – R1CH=CO]? ions) in the MS2 product-ion spectra of the [M – H]? ions desorbed by electrospray ionization (ESI). Further dissociation of the [M – H – R2CO2H]? and [M – H – R1CO2H]? ions gives rise to a pair of unique ions corresponding to losses of 74 and 56 Da (that is, [M – H – RxCO2H – 56]? and [M – H – RxCO2H – 74]? ions, x = 1, 2), respectively, probably arising from various losses of the glycerol. The profile of theion-pair in the MS3 spectrum of the [M – H – R2CO2H]? ion is readily distinguishable from in the MS3 spectrum of the [M – H – R1CO2H]? ion and thus the assignment of the fatty acid substituents at the glycerol backbone can be confirmed. The product-ion spectra of the [M – H]? ions from 2-lyso-PIM and from 1-lyso-PIM are discernible and both spectra contain a unique ion that arises from primary loss of the fatty acid substituent at the glycerol backbone, followed by loss of a bicyclic glycerophosphate ester moiety of 136 Da. The combined structural information from the MS2 and MS2 product-ion spectra permit the complex structures of PIMs that consist of various isomers to be unveiled in detail.

Hsu, Fong-Fu; Turk, John; Owens, Roisin M.; Rhoades, Elizabeth R.; Russell, David G.

2007-01-01

253

Absolute Magnitudes of Pan-STARRS PS1 Asteroids  

NASA Astrophysics Data System (ADS)

Absolute magnitude (H) of an asteroid is a fundamental parameter describing the size and the apparent brightness of the body. Because of its surface shape, properties and changing illumination, the brightness changes with the geometry and is described by the phase function governed by the slope parameter (G). Although many years have been spent on detailed observations of individual asteroids to provide H and G, vast majority of minor planets have H based on assumed G and due to the input photometry from multiple sources the errors of these values are unknown. We compute H of ~ 180 000 and G of few thousands asteroids observed with the Pan-STARRS PS1 telescope in well defined photometric systems. The mean photometric error is 0.04 mag. Because on average there are only 7 detections per asteroid in our sample, we employed a Monte Carlo (MC) technique to generate clones simulating all possible rotation periods, amplitudes and colors of detected asteroids. Known asteroid colors were taken from the SDSS database. We used debiased spin and amplitude distributions dependent on size, spectral class distributions of asteroids dependent on semi-major axis and starting values of G from previous works. H and G (G12 respectively) were derived by phase functions by Bowell et al. (1989) and Muinonen et al. (2010). We confirmed that there is a positive systematic offset between H based on PS1 asteroids and Minor Planet Center database up to -0.3 mag peaking at 14. Similar offset was first mentioned in the analysis of SDSS asteroids and was believed to be solved by weighting and normalizing magnitudes by observatory codes. MC shows that there is only a negligible difference between Bowell's and Muinonen's solution of H. However, Muinonen's phase function provides smaller errors on H. We also derived G and G12 for thousands of asteroids. For known spectral classes, slope parameters agree with the previous work in general, however, the standard deviation of G in our sample is twice as larger, most likely due to sparse phase curve sampling. In the near future we plan to complete the H and G determination for all PS1 asteroids (500,000) and publish H and G values online. This work was supported by NASA grant No. NNX12AR65G.

Veres, Peter; Jedicke, R.; Fitzsimmons, A.; Denneau, L.; Wainscoat, R.; Bolin, B.; PS1SC collaboration

2013-10-01

254

Performance Analysis of the ertPS Algorithm and Enhanced ertPS Algorithm for VoIP Services in IEEE 802.16e Systems  

NASA Astrophysics Data System (ADS)

In this paper, we analyze the extended real-time Polling Service (ertPS) algorithm in IEEE 802.16e systems, which is designed to support Voice-over-Internet-Protocol (VoIP) services with data packets of various sizes and silence suppression. The analysis uses a two-dimensional Markov Chain, where the grant size and the voice packet state are considered, and an approximation formula for the total throughput in the ertPS algorithm is derived. Next, to improve the performance of the ertPS algorithm, we propose an enhanced uplink resource allocation algorithm, called the e2rtPS algorithm, for VoIP services in IEEE 802.16e systems. The e2rtPS algorithm considers the queue status information and tries to alleviate the queue congestion as soon as possible by using remaining network resources. Numerical results are provided to show the accuracy of the approximation analysis for the ertPS algorithm and to verify the effectiveness of the e2rtPS algorithm.

Kim, Bong Joo; Hwang, Gang Uk

255

Isolation and characterization of D-serine deaminase constitutive mutants by utilization of D-serine as sole carbon or nitrogen source.  

PubMed Central

Mutants constitutive for D-serine deaminase (Dsdase) synthesis were isolated by utilizing D-serine as sole nitrogen or carbon source in the chemostat. This method generated only regulatory constitutive (dsdC) mutants. The altered dsdC gene product in these strains is apparently able to bind D-serine more efficiently than the wild-type dsdC+ gene product--a selective advantage. Constitutive synthesis of Dsdase in all of these dsdC mutants is extremely sensitive to catabolite repression, and catabolite repression is reversed by the addition of D-serine. Of the 15 mutants generated by this method, none are suppressible by supD, supE, or supF. Mutations to a low level of constitutivity (maximal specific activity of 9) occur much more frequently than mutations to a high level (maximal specific activity of 79). High level constitutive synthesis of Dsdase results from the synthesis of an altered dsdC gene product--not from loss of ability to form the dsdC product. Dsdase synthesis is not regulated by the nitrogen supply in the medium, as nitrogen starvation does not result in the derepression of Dsdase synthesis.

Bloom, F R; McFall, E

1975-01-01

256

Coexistence of WiFi and WiMAX Systems Based on PS-Request Protocols†  

PubMed Central

We introduce both the coexistence zone within the WiMAX frame structure and a PS-Request protocol for the coexistence of WiFi and WiMAX systems sharing a frequency band. Because we know that the PS-Request protocol has drawbacks, we propose a revised PS-Request protocol to improve the performance. Two PS-Request protocols are based on the time division operation (TDO) of WiFi system and WiMAX system to avoid the mutual interference, and use the vestigial power management (PwrMgt) bit within the Frame Control field of the frames transmitted by a WiFi AP. The performance of the revised PS-Request protocol is evaluated by computer simulation, and compared to those of the cases without a coexistence protocol and to the original PS-Request protocol.

Kim, Jongwoo; Park, Suwon; Rhee, Seung Hyong; Choi, Yong-Hoon; Chung, Young-uk; Hwang, Ho Young

2011-01-01

257

Coexistence of WiFi and WiMAX systems based on PS-request protocols.  

PubMed

We introduce both the coexistence zone within the WiMAX frame structure and a PS-Request protocol for the coexistence of WiFi and WiMAX systems sharing a frequency band. Because we know that the PS-Request protocol has drawbacks, we propose a revised PS-Request protocol to improve the performance. Two PS-Request protocols are based on the time division operation (TDO) of WiFi system and WiMAX system to avoid the mutual interference, and use the vestigial power management (PwrMgt) bit within the Frame Control field of the frames transmitted by a WiFi AP. The performance of the revised PS-Request protocol is evaluated by computer simulation, and compared to those of the cases without a coexistence protocol and to the original PS-Request protocol. PMID:22163721

Kim, Jongwoo; Park, Suwon; Rhee, Seung Hyong; Choi, Yong-Hoon; Chung, Young-uk; Hwang, Ho Young

2011-10-13

258

Development and characterization of sub-100 ps photomultiplier tubes  

NASA Astrophysics Data System (ADS)

We describe the evaluation of a microchannel plate (MCP) photomultiplier tube (PMT), incorporating a 3 ?m pore MCP and constant voltage anode and cathode gaps. The use of the small pore size results in PMTs with response functions of the order of 85 ps full-width-half-maximum, while the constant electric field across the anode and cathode gaps produces a uniform response function over the entire operating range of the device. The PMT was characterized on a number of facilities and employed on gas Cherenkov detectors fielded on various deuterium tritium fuel (DT) implosions on the Omega Laser Facility at the University of Rochester. The Cherenkov detectors are part of diagnostic development to measure Gamma ray reaction history for DT implosions on the National Ignition Facility.

Horsfield, C. J.; Rubery, M. S.; Mack, J. M.; Young, C. S.; Herrmann, H. W.; Caldwell, S. E.; Evans, S. C.; Sedilleo, T. J.; Kim, Y. H.; McEvoy, A.; Milnes, J. S.; Howorth, J.; Davis, B.; O'Gara, P. M.; Garza, I.; Miller, E. K.; Stoeffl, W.; Ali, Z.

2010-10-01

259

Sub-10ps monolithic and low-power photodetector readout  

SciTech Connect

Recent advances in photon detectors have resulted in high-density imaging arrays that offer many performance and cost advantages. In particular, the excellent transit time spread of certain devices show promise to provide tangible benefits in applications such as Positron Emission Tomography (PET). Meanwhile, high-density, highperformance readout techniques have not kept on pace for exploiting these developments. Photodetector readout for next generation high event rate particle identification and time-resolved PET requires a highly-integrated, low-power, and cost-effective readout technique. We propose fast waveform sampling as a method that meets these criteria and demonstrate that sub-10ps resolution can be obtained for an existing device.

Varner, Gary S.; Ruckman, Larry L

2009-02-20

260

Margins of a 16-ps/bit interferometer shift register  

NASA Astrophysics Data System (ADS)

Static and dynamic properties of an interferometer with five equal Josephson junctions are investigated as a single-flux quanta shift-register model. A flux quantum is stored in any loop without a bias current or magnetic field. A flux quantum is shifted from one interferometer loop to the adjacent one by applying a magnetic-field control pulse only to one interferometer loop at a time. Shift current margins determined statically and dynamically are larger than about + or 30%; the write current margins are + or - 25%. Within these tolerances, and for a maximum Josephson current density of 10 kA/sq cm, delays of 16 ps/bit, including shift and write, have been simulated.

Beha, H.; Jutzi, W.; Mischke, G.

1980-10-01

261

First observation of o-Ps to p-Ps transition and first direct measurement of positronium hyperfine splitting with sub-THz light  

NASA Astrophysics Data System (ADS)

Positronium is an ideal system for the research of the bound state QED. The hyperfine splitting of positronium (Ps-HFS, about 203 GHz) is an important observable but all previous measurements of Ps-HFS had been measured indirectly using Zeeman splitting. There might be the unknown systematic errors on the uniformity of magnetic field. We are trying to measure Ps-HFS directly using sub-THz radiation. We developed an optical system to accumulate high power (about 10 kW) radiation in a Fabry-Pérot resonant cavity and observed the positronium hyperfine transition for the first time.

Yamazaki, Takayuki; Miyazaki, Akira; Suehara, Taikan; Namba, Toshio; Asai, Shoji; Kobayashi, Tomio; Saito, Haruo; Urushizaki, Yuichi; Ogawa, Isamu; Idehara, Toshitaka; Sabchevski, Svilen

2012-12-01

262

First observation of o-Ps to p-Ps transition and first direct measurement of positronium hyperfine splitting with sub-THz light  

NASA Astrophysics Data System (ADS)

Positronium is an ideal system for the research of the bound state QED. The hyperfine splitting of positronium (Ps-HFS, about 203 GHz) is an important observable but all previous measurements of Ps-HFS had been measured indirectly using Zeeman splitting. There might be the unknown systematic errors on the uniformity of magnetic field. We are trying to measure Ps-HFS directly using sub-THz radiation. We developed an optical system to accumulate high power (about 10 kW) radiation in a Fabry-Pérot resonant cavity and observed the positronium hyperfine transition for the first time.

Yamazaki, Takayuki; Miyazaki, Akira; Suehara, Taikan; Namba, Toshio; Asai, Shoji; Kobayashi, Tomio; Saito, Haruo; Urushizaki, Yuichi; Ogawa, Isamu; Idehara, Toshitaka; Sabchevski, Svilen

263

Intermacromolecular complexation due to specific interactions: 3. Miscibility and complexation of PBMA and PS(OH)  

Microsoft Academic Search

The structural changes as a function of OH concentration in the blend system of poly(n-butyl methacrylate) (PBMA) and hydroxyl-modified polystyrene (PS(OH)) are investigated by a non-radiative energy transfer technique and viscometry. It is shown that, for blends cast from toluene, only 1 mol% OH concentration in PS(OH) is capable of rendering PS(OH) miscible with PBMA. When the OH concentration in

Ming Jiang

1995-01-01

264

CONCEPTUAL FRAMEWORK FOR PS-INSAR DEFORMATION INTERPRETATION ASSISTED BY GEO-INFORMATION TECHNOLOGY  

Microsoft Academic Search

Although Persistent Scatterer (PS) InSAR deformation measurements may be very precise, this does not necessarily imply a reliable estimation of the parameters of interest. PS-InSAR deformation measurements may be caused by different de- formation regimes, like gas extraction, shallow compaction or structural instabilities making unambiguous interpretation difficult. This research investigates the use of geo-information technology for the interpretation of PS-InSAR

S. Gehlot; V. B. H. Ketelaar; E. Verbree; R. F. Hanssen

265

P3HT-PS blend nanofiber FET based on electrospinning  

Microsoft Academic Search

We present the preparation of novel P3HT-PS blend nanofibers that can be utilized as active channel materials in the field effect transistors (FETs). P3HT-PS blend nanofibers were prepared using electrospinning process. The formation of nanofibers was observed under the limited conditions (in terms of solvent composition and P3HT concentration). Morphology and FET characteristics of P3HT-PS nanofibers were investigated under the

Jaehyun Hur; Seung-Nam Cha; Kyuhyun Im; Sung Won Lee; Unyong Jeong; Jongmin Kim; Jong-Jin Park

2010-01-01

266

Characterization of the biochemical and biophysical properties of the phosphatidylserine receptor (PS-R) gene product  

Microsoft Academic Search

The PS-R gene product was originally described as a cell surface receptor that interacts with externalized phosphatidylserine\\u000a (PS) on apoptotic cells, but more recent studies have shown that it plays a critical role in organ development and terminal\\u000a differentiation of many cell types during embryogenesis. Despite these important developmental functions, the biochemical\\u000a and molecular properties of PS-R are poorly understood.

Nitu Tibrewal; Tong Liu; Hong Li; Raymond B. Birge

2007-01-01

267

Calcium protection of PS2 complex of Phaseolus coccineus from cadmium toxicity: In vitro study  

Microsoft Academic Search

The action of 10 and 20mM Ca against harmful Cd effect on PS2 complex isolated from leaves of Phaseolus coccineus L. cv. Pi?kny Ja? was studied. The changes in fast chlorophyll a fluorescence induction kinetics and protein composition of PS2 complex were the symptoms of Cd toxicity and Ca protection of PS2 complex. Calcium applied at 10mM concentration prevented F0

Maria Dr??kiewicz; Tadeusz Baszy?ski

2008-01-01

268

PS1 Keyproject 02: Populations of Objects in the Outer Solar System  

Microsoft Academic Search

It is estimated that PS1 will discover 7 103 trans-neptunian objects, 4 104 Jupiter Trojans, 103 comets, and 103 Centaurs with magnitude mR < 23, scaling from estimates for PS4 (Jewitt 2003). The PS1 survey, with its unprecedented combination of depth, sky coverage, and unifor- mity, will provide us an opportunity to answer a large number of questions about the

M. J. Holman

269

Reversible unfolding of sheep liver tetrameric serine hydroxymethyltransferase.  

PubMed

Equilibrium unfolding studies of the tetrameric serine hydroxymethyltransferase from sheep liver (SHMT, E.C.2.1.2.1) revealed that the holoenzyme, apoenzyme and the sodium borohydride-reduced holoenzyme had random coil structures in 8 M urea. In the presence of a non-ionic detergent, Brij-35, and polyethylene glycol, the 8 M urea unfolded protein could be completely (> 95%) refolded by a 20-fold dilution. The refolded enzyme was completely active and kinetically similar to the native enzyme. The midpoint of inactivation of the enzyme occurred at a urea concentration that was much below the urea concentration required to bring about a substantial loss of secondary structure. This observation suggested the occurrence of a 'predenaturation transition' in the unfolding pathway. The equilibrium urea-induced denaturation curve of holoSHMT showed two transitions. The midpoint of the first transition was 1.2 M, which was comparable to that required for 50% decrease in enzyme activity. Further, 50% release of the pyridoxal-5'-phosphate (PLP) from the active site, as monitored by decrease in absorbance at 425 nm, also occurred at about 1.2 M urea. Size exclusion chromatography showed that the tetrameric SHMT unfolds via the intermediate formation of dimers. This dissociation occurred at a much lower urea concentration (0.15 M) in the unfolding of the apoenzyme, and at a higher urea concentration (1.2 M) in the unfolding of holoenzyme, thereby demonstrating the involvement of PLP in stabilizing the quaternary structure of the enzyme. Size exclusion chromatography of the refolding intermediates demonstrated that the cofactor shifts the equilibrium towards the formation of the active tetramer. The reduced holoenzyme could also be refolded to its native structure, as observed by fluorescence and CD measurements, indicating that the presence of covalently linked PLP does not affect refolding. The results demonstrate clearly that the dimer is an intermediate in the urea-induced equilibrium unfolding/refolding of sheep liver SHMT; and PLP, in addition to its role in catalysis, is required for the stabilization of the tetrameric structure of the enzyme. PMID:9602099

Venkatesha, B; Udgaonkar, J B; Rao, N A; Savithri, H S

1998-04-23

270

Microfabricated device for co-culture of sympathetic neuron and iPS-derived cardiomyocytes.  

PubMed

Induced pluripotent stem (iPS) cell-derived cardiomyocytes (iPS-CMs) has been expected as a cell source for therapy of serious heart failure. However, it is unclear whether the function of iPS-CMs is modulated by the host sympathetic nervous system. Here we developed a device for co-culture of sympathetic neurons and iPS-CMs using microfabrication technique. The device consisted of a culture chamber and a microelectrode-array (MEA) substrate. The superior cervical ganglion (SCG) neurons were co-cultured with iPS-CMs in a microfabricated device, which had multiple compartments. Several days after seeding, synapses were formed between SCG neurons and iPS-CMs, as confirmed by immunostaining. Spontaneous electrical activities of the SCG neurons and the iPS-CMs were observed from the electrode of the MEA substrate. The beat rate of iPS-CMs increased after electrical stimulation of the co-cultured SCG neurons. Such changes in the beat rate were prevented in the presence of propranolol, a ?-adrenoreceptor antagonist. These results suggest that the microfabricated device will be utilized for studying the functional modulation of iPS-CMs by connected sympathetic neurons. PMID:24110563

Takeuchi, Akimasa; Shimba, Kenta; Takayama, Yuzo; Kotani, Kiyoshi; Lee, Jong-Kook; Noshiro, Makoto; Jimbo, Yasuhiko

2013-07-01

271

Complete Fragmentation of Ortho ps - He+ Ion System and the Elc Process  

NASA Astrophysics Data System (ADS)

The dynamics of the complete breakup process in an Ortho Ps - He + system, including electron loss to the continuum (ELC) is studied where both the projectile and the target get ionized. The process is essentially a four body problem and the present model takes account of the two centre effect on the electron ejected from the Ps atom which is crucial for a proper description of the ELC phenomena. A distinct broad ELC peak is noted in the fully differential cross sections (FDCS) for the PS electron, corroborating qualitatively the experiment for the Ps - He system.

Sinha, C.; Mukhopadhyay, S.; Ghosh, D.

2012-11-01

272

Allosteric activation and contrasting properties of L-serine dehydratase types 1 and 2.  

PubMed

Bacterial L-serine dehydratases differ from mammalian L- and D-serine dehydratases and bacterial D-serine dehydratases by the presence of an iron-sulfur center rather than a pyridoxyl phosphate prosthetic group. They exist in two forms, types 1 and 2, distinguished by their sequence and oligomeric configuration. Both types contain an ASB domain, and the type 1 enzymes also contain an ACT domain in a tandem arrangement with the ASB domain like that in type 1 D-3-phosphoglycerate dehydrogenases (PGDHs). This investigation reveals striking kinetic differences between L-serine dehydratases from Bacillus subtilis (bsLSD, type 1) and Legionella pneumophila (lpLSD, type 2). lpLSD is activated by monovalent cations and inhibited by monovalent anions. bsLSD is strongly activated by cations, particularly potassium, and shows a mixed response to anions. Flouride is a competitive inhibitor for lpLSD but an apparent activator for bsLSD at low concentrations and an inhibitor at high concentrations. The reaction products, pyruvate and ammonia, also act as activators but to different extents for each type. Pyruvate activation is competitive with L-serine, but activation of the enzyme is not compatible with it simply competing for binding at the active site and suggests the presence of a second, allosteric site. Because activation can be eliminated by higher levels of L-serine, it may be that this second site is actually a second serine binding site. This is consistent with type 1 PGDH in which the ASB domain functions as a second site for substrate binding and activation. PMID:22686449

Chen, Shawei; Xu, Xiao Lan; Grant, Gregory A

2012-06-20

273

WFDC1/ps20: a host factor that influences the neutrophil response to murine hepatitis virus (MHV) 1 infection.  

PubMed

The whey acidic protein family member, WFDC1/ps20 is a permissivity factor in HIV infection. Herein we describe a contrasting role for ps20 in limiting MHV-1 infection. Intranasal MHV-1 infection produces a respiratory infection in mice. Using ps20 knockout mice we provide evidence that intranasal MHV-1 infection results in increased lung viral titers in ps20(-/-) compared to ps20(+/+) mice. Accompanying MHV-1 infection we observe an increase in the number of neutrophils infiltrating the BAL and an increase in the percentage of neutrophils in the lung draining lymph nodes of ps20(-/-) compared with ps20(+/+) mice. Gene expression levels for the neutrophil chemoattractants CXCL1 and CXCL2 are elevated in the lungs of ps20(-/-) mice post-MHV-1 infection. Characterization of the immune cell profile in naïve ps20(-/-) mice revealed an increase in circulating neutrophils compared to ps20(+/+) mice. No notable differences in other immune cell profiles were observed between the ps20(+/+) and ps20(-/-) mice. Accordingly, we examined MHV-1 infection of neutrophils and provide evidence that neutrophils isolated from ps20(-/-) mice are more susceptible to MHV-1 infection than neutrophils isolated from ps20(+/+) mice. These data suggest roles for ps20 in regulating expression of neutrophil-specific chemotactic factors, thereby potentially modulating neutrophil migration, and in modulating neutrophil susceptibility to MHV-1 infection. PMID:22960155

Rogers, Erin; Wang, Ben X; Cui, Zhu; Rowley, David R; Ressler, Steven J; Vyakarnam, Annapurna; Fish, Eleanor N

2012-09-06

274

The effect of L-2-amino-4-methoxy-trans-3-butenoic acid on serine hydroxymethyl transferase.  

PubMed

The tumour growth inhibitor L-2-amino-4-methoxy-trans-3-butenoic acid (Ro07-7957) inhibits serine hydroxymethyltransferase in cytosolic extracts of Walker carcinoma non-competitively with respect to L-serine with an apparent inhibition constant similar to the Km-value for L-serine. The kinetics of inactivation suggest that it reacts as an irreversible substrate analogue. Incubation of Walker cells with Ro07-7957 causes an increase in serine hydroxymethyltransferase activity which is most pronounced at concentrations less than or equal to LD50. This increase in enzyme activity does not occur in the presence of cycloheximide. These results suggest that inhibition of serine hydroxymethyltransferase in intact cells is accompanied by an increase in enzyme biosynthesis and that the growth inhibitory property or Ro07-7957 does not involve interference with the conversion of serine to glycine. PMID:7460079

Tisdale, M J

1981-02-01

275

Enhanced function annotations for Drosophila serine proteases: A case study for systematic annotation of multi-member gene families  

Microsoft Academic Search

Systematicallyannotatingfunctionofenzymesthatbelongtolargeproteinfamiliesencodedinasingleeukaryoticgenomeisaverychallengingtask. We carried out such an exercise to annotate function for serine-protease family of the trypsin fold in Drosophila melanogaster, with an emphasis on annotating serine-protease homologues (SPHs) that may have lost their catalytic function. Our approach involves data mining and data integration to providefunction annotations for 190Drosophilagene products containing serine-protease-like domains,ofwhich 35areSPHs. Thiswas accomplished by analysis of structure-function relationships,

Parantu K. Shah; Lokesh P. Tripathi; Lars Juhl Jensen; Murad Gahnim; Christopher Mason; Eileen E. Furlong; Veronica Rodrigues; Kevin P. White; Peer Bork; R. Sowdhamini

2007-01-01

276

RNA interference (RNAi) for the silencing of extracellular serine proteases genes in Acanthamoeba: Molecular analysis and effect on pathogenecity  

Microsoft Academic Search

Silencing of extracellular serine protease genes was undertaken by interference RNA (RNAi). Chemically synthesized, small interfering RNA (siRNA) were highly specific and efficient in silencing the catalytic domain of extracellular serine proteases of Acanthamoeba. In order to confirm the silencing phenomenon, the extracellular serine protease activities in RNAi-treated parasites were compared to non-treated parasites, using zymography profiles, Acanthamoeba-conditioned medium (ACM)

Jacob Lorenzo-Morales; Antonio Ortega-Rivas; Pilar Foronda; Néstor Abreu-Acosta; David Ballart; Enrique Martínez; Basilio Valladares

2005-01-01

277

Astrocyte-induced cortical vasodilation is mediated by D-serine and endothelial nitric oxide synthase.  

PubMed

Astrocytes play a critical role in neurovascular coupling by providing a physical linkage from synapses to arterioles and releasing vaso-active gliotransmitters. We identified a gliotransmitter pathway by which astrocytes influence arteriole lumen diameter. Astrocytes synthesize and release NMDA receptor coagonist, D-serine, in response to neurotransmitter input. Mouse cortical slice astrocyte activation by metabotropic glutamate receptors or photolysis of caged Ca(2+) produced dilation of penetrating arterioles in a manner attenuated by scavenging D-serine with D-amino acid oxidase, deleting the enzyme responsible for D-serine synthesis (serine racemase) or blocking NMDA receptor glycine coagonist sites with 5,7-dichlorokynurenic acid. We also found that dilatory responses were dramatically reduced by inhibition or elimination of endothelial nitric oxide synthase and that the vasodilatory effect of endothelial nitric oxide synthase is likely mediated by suppressing levels of the vasoconstrictor arachidonic acid metabolite, 20-hydroxy arachidonic acid. Our results provide evidence that D-serine coactivation of NMDA receptors and endothelial nitric oxide synthase is involved in astrocyte-mediated neurovascular coupling. PMID:23386721

Stobart, Jillian L LeMaistre; Lu, Lingling; Anderson, Hope D I; Mori, Hisashi; Anderson, Christopher M

2013-02-05

278

Paradox of mistranslation of serine for alanine caused by AlaRS recognition dilemma.  

PubMed

Mistranslation arising from confusion of serine for alanine by alanyl-tRNA synthetases (AlaRSs) has profound functional consequences. Throughout evolution, two editing checkpoints prevent disease-causing mistranslation from confusing glycine or serine for alanine at the active site of AlaRS. In both bacteria and mice, Ser poses a bigger challenge than Gly. One checkpoint is the AlaRS editing centre, and the other is from widely distributed AlaXps-free-standing, genome-encoded editing proteins that clear Ser-tRNA(Ala). The paradox of misincorporating both a smaller (glycine) and a larger (serine) amino acid suggests a deep conflict for nature-designed AlaRS. Here we show the chemical basis for this conflict. Nine crystal structures, together with kinetic and mutational analysis, provided snapshots of adenylate formation for each amino acid. An inherent dilemma is posed by constraints of a structural design that pins down the alpha-amino group of the bound amino acid by using an acidic residue. This design, dating back more than 3 billion years, creates a serendipitous interaction with the serine OH that is difficult to avoid. Apparently because no better architecture for the recognition of alanine could be found, the serine misactivation problem was solved through free-standing AlaXps, which appeared contemporaneously with early AlaRSs. The results reveal unconventional problems and solutions arising from the historical design of the protein synthesis machinery. PMID:20010690

Guo, Min; Chong, Yeeting E; Shapiro, Ryan; Beebe, Kirk; Yang, Xiang-Lei; Schimmel, Paul

2009-12-10

279

Identification of Serine/Threonine Kinase Substrates in the Human Pathogen Group B Streptococcus  

PubMed Central

All living organisms respond to changes in their internal and external environment for their survival and existence. Signaling is primarily achieved through reversible phosphorylation of proteins in both prokaryotes and eukaryotes. A change in the phosphorylation state of a protein alters its function to enable the control of cellular responses. A number of serine/threonine kinases regulate the cellular responses of eukaryotes. Although common in eukaryotes, serine/threonine kinases have only recently been identified in prokaryotes. We have described that the human pathogen Group B Streptococcus (GBS, Streptococcus agalactiae) encodes a single membrane-associated, serine/threonine kinase (Stk1) that is important for virulence of this bacterium. In this study, we used a combination of phosphopeptide enrichment and mass spectrometry to enrich and identify serine (S) and threonine (T) phosphopeptides of GBS. A comparison of S/T phosphopeptides identified from the Stk1 expressing strains to the isogenic stk1 mutant indicates that 10 proteins are potential substrates of the GBS Stk1 enzyme. Some of these proteins are phosphorylated by Stk1 in vitro and a site-directed substitution of the phosphorylated threonine to an alanine abolished phosphorylation of an Stk1 substrate. Collectively, these studies provide a novel approach to identify serine/threonine kinase substrates for insight into their signaling in human pathogens like GBS.

Silvestroni, Aurelio; Jewell, Kelsea A.; Lin, Wan-Jung; Connelly, James E.; Ivancic, Melanie M.; Tao, W. Andy; Rajagopal, Lakshmi

2010-01-01

280

Paradox of mistranslation of serine for alanine caused by AlaRS recognition dilemma  

PubMed Central

Mistranslation from confusion of serine for alanine by alanyl-tRNA synthetases (AlaRSs) has profound functional consequences1-3. Throughout evolution, two editing-checkpoints prevent disease-causing mistranslation from confusing glycine or serine for alanine at the active site of AlaRS. In both bacteria and mice, Ser poses a bigger challenge than Gly1,2. One checkpoint is the AlaRS editing center, while the other is from widely distributed AlaXps—free-standing, genome-encoded editing proteins that clear Ser-tRNAAla. The paradox of misincorporating both a smaller (glycine) and a larger amino acid (serine) suggests a deep conflict for nature-designed AlaRS. To understand the chemical basis for this conflict, kinetic and mutational analysis, together with nine crystal structures, provided snapshots of adenylate formation for each amino acid. An inherent dilemma is posed by constraints of a structural design that pins down the ?–amino group of the bound amino acid using an acidic residue. This design, of more than 3 billion years, creates a serendipitous interaction with the serine OH that is difficult to avoid. Apparently not able to find better architecture for recognition of alanine, the serine misactivation problem was solved through free-standing AlaXps, which appeared contemporaneously with early AlaRSs. The results reveal unconventional problems and solutions arising from the historical design of the protein synthesis machinery.

Guo, Min; Chong, Yeeting E.; Shapiro, Ryan; Beebe, Kirk; Yang, Xiang-Lei; Schimmel, Paul

2009-01-01

281

D-serine-dehydratase from Saccaromyces cerevisiae: a pyridoxal 5'- phosphate-dependent enzyme for advanced biotech applications.  

PubMed

The Saccaromices cerevisiae D-serine dehydratase is a pyridoxal 5'-phosphate dependent enzyme that requires zinc for its function. It catalyses the conversion of D-serine into pyruvate and ammonia with the K(m) and k(cat) values of 0.39 mM and 13.1 s(-1) respectively. In this work, a new methodology for monitoring D-serine is presented. Our results show that this enzyme could be successfully used as a biological probe for detection of D-serine via fluorescence spectroscopy. PMID:22519530

Staiano, Maria; Strianese, Maria; Varriale, Antonio; Di Giovanni, Stefano; di Mase, Donatella Scotto; Dell'Angelo, Valentina; Ruggiero, Giuseppe; Labella, Tullio; Pellecchia, Claudio; D'Auria, Sabato

2012-06-01

282

PS300 Tribomaterials Evaluated at 6500C by Bushing Test Rig.  

National Technical Information Service (NTIS)

A new facility has been developed to test the tribological behavior (friction and wear) of PS300 solid lubricant bushings at high temperatures. PS300 is a commercially available solid lubricant invented at the NASA Glenn Research Center. It can be prepare...

D. R. Striebing C. DellaCorte

2004-01-01

283

Immunolocalization of PsNLEC-1, a lectin-like glycoprotein expressed in developing pea nodules.  

PubMed Central

The pea (Pisum sativum) nodule lectin gene PsNlec1 is a member of the legume lectin gene family that is strongly expressed in infected pea nodule tissue. A full-length cDNA sequence of PsNlec1 was expressed in Escherichia coli and a specific antiserum was generated from the purified protein. Immunoblotting of material from isolated symbiosomes revealed that the glycoprotein was present in two antigenic isoforms, PsNLEC-1A and PsNLEC-1B. The N-terminal sequence of isoform A showed homology to an eight-amino acid propeptide sequence previously identified from the cDNA sequence of isoform B. In nodule homogenates the antiserum recognized an additional fast-migrating band, PsNLEC-1C. Fractionation studies indicated that PsNLEC-1C was associated with a 100,000 g nodule membrane fraction, suggesting an association with cytoplasmic membrane or vesicles. Immunogold localization in pea nodule tissue sections demonstrated that the PsNLEC-1 antigen was present in the symbiosome compartment and also in the vacuole but revealed differences in distribution between infected host cells in different parts of the nodule. These data suggest that PsNLEC-1 is subject to posttranslational modification and that the various antigenic isoforms can be used to monitor membrane and vesicle targeting during symbiosome development.

Dahiya, P; Kardailsky, I V; Brewin, N J

1997-01-01

284

Complete Nucleotide Sequence of Canine Distemper Virus CDV-PS, Isolated from Dogs in China.  

PubMed

A new strain of canine distemper virus, CDV-PS, has been isolated from dogs in China, and its complete genome has been sequenced and analyzed. The phylogenetic analysis suggests that CDV-PS belongs to the Asia-1 cluster and has low identity to the vaccine strain. PMID:23682141

Yi, Li; Xu, Hongli; Wang, Jianke; Cheng, Yuening; Zhang, Hailing; Yan, Xijun; Cheng, Shipeng

2013-05-16

285

Complex-Scaling Calculations for Doubly Excited Resonances in Ps- Interacting with Screened Coulomb (Yukawa) Potentials  

NASA Astrophysics Data System (ADS)

We have investigated the effect of screened Coulomb potentials on the high-lying doubly excited resonance states of the positronium negative ion in the framework of complex-scaling method. Highly correlated wave functions in Hylleraas coordinates are used. The resonance parameters below the Ps (2s2S) and Ps (3s2S) thresholds, for various screening parameters, are reported.

Ho, Y. K.; Kar, S.

2012-10-01

286

Stimulated Brillouin scattering pulse compression to 175 ps in a fused quartz at 1064 nm  

NASA Astrophysics Data System (ADS)

Stimulated Brillouin scattering pulse compression of a 2.5 ns laser into a 175 ps pulse using a fused quartz is demonstrated without optical damage. The synchronization and the time jitter between the initial and the compressed pulses were measured (?<80 ps) and analyzed numerically.

Marcus, Gilad; Pearl, Shaul; Pasmanik, Guerman

2008-05-01

287

Effects of hypoxia on pluripotency in murine iPS cells.  

PubMed

Retroviral transduction of four transcription factors (Oct4, Sox2, Klf4 and c-Myc) or three factors, excluding c-Myc, has been shown to initiate a reprogramming process that results in the transformation of murine fibroblasts to induced pluripotent stem (iPS) cells, and there has been a rapid increase in the number of iPS cell-based preclinical trials. In this study, the effects of these transcription factors were evaluated regarding the growth and differentiation of murine iPS cells under hypoxia. Based on the results of RT-PCR and alizarin red S staining, there were no statistical differences in the growth and differentiation of iPS cells or the induction of iPS cells to osteoblasts under hypoxia between the transcription factor groups. Furthermore, the function of hypoxia inducible factors (HIFs) in murine iPS cells under hypoxia was investigated in relation to the morphology and expression of transcription factors using RT-PCR and Western blotting. The HIF-2? knockdown group exhibited a decrease in the colony size of the iPS cells. The HIF-2? or -3? knockdown group demonstrated a statistically significant decrease in the transcription factor expression compared to that observed in the control group. These results demonstrate that HIF-2? among HIFs is the most influential candidate for the maintenance of the pluripotency of murine iPS cells. Microsc. Res. Tech., 76:1084-1092, 2013. © 2013 Wiley Periodicals, Inc. PMID:23878105

Sugimoto, Kouji; Yoshizawa, Yuu; Yamada, Shizuka; Igawa, Kazunari; Hayashi, Yoshihiko; Ishizaki, Hidetaka

2013-07-23

288

Mitogen inactivation of glycogen synthase kinase-3 beta in intact cells via serine 9 phosphorylation.  

PubMed Central

Glycogen synthase kinase-3 (GSK-3), a protein-serine kinase implicated in cell-fate determination and differentiation, phosphorylates several regulatory proteins that are activated by dephosphorylation in response to hormones or growth factors. GSK-3 beta is phosphorylated in vitro at serine 9 by p70 S6 kinase and p90rsk-1, resulting in its inhibition [Sutherland, Leighton, and Cohen (1993) Biochem. J. 296, 15-19]. Using HeLa cells expressing GSK-3 beta or a mutant containing alanine at residue 9, we demonstrate that serine 9 is modified in intact cells and is targeted specifically by p90rsk-1, and that phosphorylation leads to loss of activity. Since p90rsk-1 is directly activated by mitogen-activated protein kinases, agonists of this pathway, such as insulin, repress GSK-3 function. Images Figure 1 Figure 2

Stambolic, V; Woodgett, J R

1994-01-01

289

Identification of the active-site serine in human lecithin: cholesterol acyltransferase  

SciTech Connect

Lecithin:cholesterol acyltransferase (LCAT) from human plasma reacts stoichiometrically with diisopropylphosphorofluoridate (DFP) resulting in the complete loss of transacylase activity. Purified LCAT was covalently labeled with (TH) DFP and the labeled protein was reduced and carboxymethylated. Cyanogen bromide cleavage followed by gel permeation chromatography yielded a peptide of 4-5 KDa (LCAT CNBr-III) containing most of the radioactive label. Preliminary studies comparing the amino acid composition of the LCAT-CNBr-III with the sequence of LCAT indicate that this peptide corresponds to fragment 168-220. Automated Edman degradation of the radioactive peptide recovered a radioactive PTC-amino acid at cycle 14. Of all predicted CNBr fragments only peptide 168-220 contained a serine at residue 14 from the amino terminus of the peptide. The authors conclude that serine 181 is the active site serine of LCAT.

Farooqui, J.; Wohl, R.C.; Kezdy, F.J.; Scanu, A.M.

1987-05-01

290

Structural Insights into Serine-rich Fimbriae from Gram-positive Bacteria*  

PubMed Central

The serine-rich repeat family of fimbriae play important roles in the pathogenesis of streptococci and staphylococci. Despite recent attention, their finer structural details and precise adhesion mechanisms have yet to be determined. Fap1 (Fimbriae-associated protein 1) is the major structural subunit of serine-rich repeat fimbriae from Streptococcus parasanguinis and plays an essential role in fimbrial biogenesis, adhesion, and the early stages of dental plaque formation. Combining multidisciplinary, high resolution structural studies with biological assays, we provide new structural insight into adhesion by Fap1. We propose a model in which the serine-rich repeats of Fap1 subunits form an extended structure that projects the N-terminal globular domains away from the bacterial surface for adhesion to the salivary pellicle. We also uncover a novel pH-dependent conformational change that modulates adhesion and likely plays a role in survival in acidic environments.

Ramboarina, Stephanie; Garnett, James A.; Zhou, Meixian; Li, Yuebin; Peng, Zhixiang; Taylor, Jonathan D.; Lee, Wei-chao; Bodey, Andrew; Murray, James W.; Alguel, Yilmaz; Bergeron, Julien; Bardiaux, Benjamin; Sawyer, Elizabeth; Isaacson, Rivka; Tagliaferri, Camille; Cota, Ernesto; Nilges, Michael; Simpson, Peter; Ruiz, Teresa; Wu, Hui; Matthews, Stephen

2010-01-01

291

Partial amino acid sequence of human factor D:homology with serine proteases.  

PubMed Central

Human factor D purified to homogeneity by a modified procedure was subjected to NH2-terminal amino acid sequence analysis by using a modified automated Beckman sequencer. We identified 48 of the first 57 NH2-terminal amino acids in a single sequencer run, using microgram quantities of factor D. The deduced amino acid sequence represents approximately 25% of the primary structure of factor D. This extended NH2-terminal amino acid sequence of factor D was compared to that of other trypsin-related serine proteases. By visual inspection, strong homologies (33--50% identity) were observed with all the serine proteases included in the comparison. Interestingly, factor D showed a higher degree of homology to serine proteases of pancreatic origin than to those of serum origin. Images

Volanakis, J E; Bhown, A; Bennett, J C; Mole, J E

1980-01-01

292

iPS cell technology-based research for the treatment of diabetic nephropathy.  

PubMed

Regenerative medicine strategies using induced pluripotent stem (iPS) cells are among the candidate approaches to treat diabetic nephropathy caused by type 1 diabetes. Cell transplantation therapy and disease modeling with patient-derived iPS cells should be examined for diabetic renal disease. Considerable work already has been performed with regard to the generation of renal lineage cells from mouse embryonic stem cells, however, few reports have described research with human embryonic stem cells or iPS cells. Further elucidation of the mechanisms of kidney development and establishing the method for directed differentiation from human iPS cells into renal lineage cells will be required for the development of iPS cell technology-based treatment for diabetic nephropathy. PMID:23062989

Osafune, Kenji

2012-09-01

293

Study of mechanical properties of polyvinyl chloride (PVC) and polystyrene (PS) polymers and their blends  

NASA Astrophysics Data System (ADS)

Presented work is an effort to observe the variation in mechanical properties of two thermoplastic materials PVC, PS and their blends. PVC and PS are taken in the ratio of 100:0, 70:30, 50:50, and 0:100. Mixing of PVC and PS is carried out by solution casting method using tetra hydro furan as solvent. Dynamical mechanical analyzer (DMA) is used to study mechanical properties. The storage modulus, loss modulus and mechanical loss factor (tan ?) are determined with temperature. The pallets of pure PS, PVC and their blends are scanned over a temperature range from room to 140 °C. The variation of modulus, tan ? of pure PVC & pure PS and their blends with temperature were studied. The observed variation in modulus and tan ? could be accounted for their thermal behavior and compositions.

Agarwal, Shalini; Saxena, N. S.; Agrawal, R.; Saraswat, Vibhav K.

2013-06-01

294

A search for sterile neutrinos at CERN-PS  

NASA Astrophysics Data System (ADS)

The LSND experiment has observed a 3.8 sigma excess of bar nue events from an bar nu? beam coming from pions at rest. If confirmed, the LSND anomaly would imply new physics beyond the standard model. The MiniBooNE experiment shows a 1.6 ? disagreement with LSND results, but it introduces an unexplained, new 3.0 sigma anomaly at lower energies, down to 200 MeV. The proposal for a new eperiment based on two liquidArgon TPCs at CERN-PS is presented in this paper. The superior quality of the Liquid Argon imaging TPC and its unique electron - pi-zero discrimination allow full rejection of the NC background, without efficiency loss for electron neutrino detection. The use of two detectors at a near and a far location enables to minimize the effects of systematic uncertainties related to the neutrino beam and to the neutrino cross-sections. This experiment could collect 106 charged current events in two years data taking, thus allowing for a high priecision and high statistics study of the LSND and MiniBoone anomalies

Calligarich, E.; Centro, S.; Gibin, D.; Guglielmi, A.; Pietropaolo, F.; Rubbia, C.; Sala, P. R.

2010-01-01

295

A Critical Appraisal of NLO+PS Matching Methods  

SciTech Connect

In this publication, uncertainties in and differences between the MC{at}NLO and POWHEG methods for matching next-to-leading order QCD calculations with parton showers are discussed. Implementations of both algorithms within the event generator SHERPA are employed to assess the impact on a representative selection of observables. In the MC{at}NLO approach a phase space restriction has been added to subtraction and parton shower, which allows to vary in a transparent way the amount of non-singular radiative corrections that are exponentiated. Effects on various observables are investigated, using the production of a Higgs boson in gluon fusion, with or without an associated jet, as a benchmark process. The case of H+jet production is presented for the first time in an NLO+PS matched simulation. Uncertainties due to scale choices and non-perturbative effects are explored in the production of W{sup {+-}} and Z bosons in association with a jet. Corresponding results are compared to data from the Tevatron and LHC experiments.

Hoeche, Stefan; /SLAC; Krauss, Frank; Schonherr, Marek; /Durham U., IPPP; Siegert, Frank; /Freiburg U.

2012-03-19

296

Chromosome mapping in Pseudomonas syringae pv. syringae strain PS224.  

PubMed

A conjugation system for mapping the chromosome of Pseudomonas syringae pv. syringae PS224 has been developed using the IncP-10 plasmid R91-5; pMO22, a Tn501-loaded derivative of R91-5; and pMO75, R91-5 loaded with Tn5. Nine different donor origins were identified with R91-5 and pMO22. By insertion of Tn5 into various sites of the chromosome, an additional six donor origins were available using pMO75 as the donor plasmid. In all, 36 markers were located on three linkage groups. Many donor strains were unstable and the limited availability of stable donor strains has limited the extent to which markers have been located. This instability of donor strains is in marked contrast to the highly stable donor strains found in P. putida using the same plasmids. As in P. aeruginosa and P. putida, auxotrophic markers in P. syringae do not show the clustering of related markers found in enterobacteria. PMID:2172444

Nordeen, R O; Holloway, B W

1990-07-01

297

A critical appraisal of NLO+PS matching methods  

NASA Astrophysics Data System (ADS)

In this publication, uncertainties in and differences between the M C@NLO and P OWHEG methods for matching next-to-leading order QCD calculations with parton showers are discussed. Implementations of both algorithms within the event generator S HERPA and based on Catani-Seymour subtraction are employed to assess the impact on a representative selection of observables. In the case of M C@NLO a substantial simplification is achieved by using dipole subtraction terms to generate the first emission. A phase space restriction is employed, which allows to vary in a transparent way the amount of non-singular radiative corrections that are exponentiated. Effects on various observables are investigated, using the production of a Higgs boson in gluon fusion, with or without an associated jet, as a benchmark process. The case of H+jet production is presented for the first time in an NLO+PS matched simulation. Uncertainties due to scale choices and non-perturbative effects are explored in the production of W ± and Z bosons in association with a jet. Corresponding results are compared to data from the Tevatron and LHC experiments.

Höche, Stefan; Krauss, Frank; Schönherr, Marek; Siegert, Frank

2012-09-01

298

Re-Introduction of Transmembrane Serine Residues Reduce the Minimum Pore Diameter of Channelrhodopsin-2  

PubMed Central

Channelrhodopsin-2 (ChR2) is a microbial-type rhodopsin found in the green algae Chlamydomonas reinhardtii. Under physiological conditions, ChR2 is an inwardly rectifying cation channel that permeates a wide range of mono- and divalent cations. Although this protein shares a high sequence homology with other microbial-type rhodopsins, which are ion pumps, ChR2 is an ion channel. A sequence alignment of ChR2 with bacteriorhodopsin, a proton pump, reveals that ChR2 lacks specific motifs and residues, such as serine and threonine, known to contribute to non-covalent interactions within transmembrane domains. We hypothesized that reintroduction of the eight transmembrane serine residues present in bacteriorhodopsin, but not in ChR2, will restrict the conformational flexibility and reduce the pore diameter of ChR2. In this work, eight single serine mutations were created at homologous positions in ChR2. Additionally, an endogenous transmembrane serine was replaced with alanine. We measured kinetics, changes in reversal potential, and permeability ratios in different alkali metal solutions using two-electrode voltage clamp. Applying excluded volume theory, we calculated the minimum pore diameter of ChR2 constructs. An analysis of the results from our experiments show that reintroducing serine residues into the transmembrane domain of ChR2 can restrict the minimum pore diameter through inter- and intrahelical hydrogen bonds while the removal of a transmembrane serine results in a larger pore diameter. Therefore, multiple positions along the intracellular side of the transmembrane domains contribute to the cation permeability of ChR2.

Richards, Ryan; Dempski, Robert E.

2012-01-01

299

Endogenous phosphorylation of the lipoprotein-associated coagulation inhibitor at serine-2.  

PubMed Central

Lipoprotein-associated coagulation inhibitor (LACI) inhibits activated Factor X (Xa) directly and, in an Xa-dependent fashion, inhibits Factor VIIa-tissue factor (TF), presumably by forming a quaternary Xa-LACI-VIIa-TF complex. LACI isolated from the conditioned media of HepG2 cells grown in the presence of [32P]orthophosphate was observed to be covalently phosphorylated. Dephosphorylation of 32P-LACI with phosphatase resulted in an almost complete removal of the radiolabel. Phosphoamino acid analysis of the purified 32P-LACI established that the phosphorylation occurred on (a) serine residue(s). At its N-terminus, LACI contains a cluster of acidic residues C-terminal to the serine-2 residue. Such a site is characteristic of the sites phosphorylated by casein kinase II (CKII) in protein substrates. Edman degradation of endogenously labelled 32P-LACI revealed that the serine-2 residue was a major site of phosphorylation. Phosphorylation of purified LACI by bovine CKII was observed to occur in vitro; amino acid sequence analysis demonstrated that CKII phosphorylated LACI at the serine-2 residue. Recombinant LACI expressed from mouse C127 fibroblasts transfected using a bovine-papilloma-virus expression vector was found to be endogenously phosphorylated. By using site-directed mutagenesis, an altered form of LACI was produced in which the serine-2 residue had been changed to alanine. This altered LACI, although expressed in similar quantity to the wild-type LACI, was not detectably phosphorylated. Using the altered LACI in functional studies demonstrated that a serine residue at position 2, and thus the phosphorylation of this site, was not essential for LACI's inhibition of Xa and VIIa-TF activities. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4.

Girard, T J; McCourt, D; Novotny, W F; MacPhail, L A; Likert, K M; Broze, G J

1990-01-01

300

Longistatin is an unconventional serine protease and induces protective immunity against tick infestation.  

PubMed

Classical serine proteases use the conserved Ser/His/Asp catalytic triad to hydrolyze substrates. Here, we show that longistatin, a salivary gland protein with two EF-hand domains from the vector tick Haemaphysalis longicornis, does not have the conserved catalytic triad, but still functions as a serine protease. Longistatin was synthesized in and secreted from the salivary glands of ticks, and is injected into host tissues during the acquisition of blood-meals. Longistatin hydrolyzed fibrinogen, an essential plasma protein in the coagulation cascade, and activated plasminogen, into its active form plasmin, a serine protease that dissolves fibrin clots. Longistatin efficiently hydrolyzed several serine protease-specific substrates showing its specificity to the amide bond of Arg. Longistatin did not hydrolyze synthetic substrates specific for other groups of proteases. The enzyme was active at a wide range of temperatures and pHs, with the optimum at 37°C and pH 7. Its activity was efficiently inhibited by various serine protease inhibitors such as phenylmethanesulfonyl fluoride (PMSF), aprotinin, antipain, and leupeptin with the estimated IC(50) of 278.57 ?M, 0.35 ?M, 41.56 ?M and 198.86 ?M, respectively. In addition, longistatin was also potently inhibited by Zinc (Zn(2+)) in a concentration-dependent manner with an IC(50) value of 275 ?M, and the inhibitory effect of Zn(2+) was revived by ethylenediaminetetra acetic acid (EDTA). Immunization studies revealed that longistatin sharply induced high levels of protective IgG antibodies against ticks. Immunization with longistatin reduced repletion of ticks by about 54%, post engorgement body weight by >11% and molting of nymphs by approximately 34%; thus, the vaccination trial was approximately 73% effective against tick infestation. Taken together, our results suggest that longistatin is a new potent atypical serine protease, and may be an interesting candidate for the development of anti-tick vaccines. PMID:22206819

Anisuzzaman; Islam, M Khyrul; Alim, M Abdul; Miyoshi, Takeharu; Hatta, Takeshi; Yamaji, Kayoko; Matsumoto, Yasunobu; Fujisaki, Kozo; Tsuji, Naotoshi

2011-12-21

301

Effects of serine mutations in transmembrane domain 7 of the human norepinephrine transporter on substrate binding and transport.  

PubMed

Two serine residues in the beta-adrenergic receptor (beta-AR) have been proposed to form hydrogen bonds with the catechol moiety of the ligand and contribute to the activation of the receptor. These conserved serine residues in the dopamine (DA) and norepinephrine transporters (DAT and NET, respectively) have also been shown to affect substrate transport in the rat DAT. In the present work, hydrogen bonding interactions between the corresponding serine residues in the human NET (hNET), 354 and 357, and the hydroxyl groups on the substrate were systematically evaluated by examining the transport and binding properties of DA and several single hydroxyl analogues of DA at wild-type and serine-to-alanine-substituted transporters. A comparison of [3H]nisoxetine binding at the serine 354 mutant, in which K(D) increased 70-fold from the wild-type value, with the binding of DA, m-tyramine (m-TYR), and p-tyramine (p-TYR) at mutant 354, where the increase in Ki was less dramatic, revealed that serine 354 is more influential in inhibitor than substrate binding. The binding of m-TYR and p-TYR at the serine 354 and serine 357 mutants did not show a direct interaction between one serine and one substrate catechol hydroxyl group. DA, m-TYR, and p-TYR binding affinity did not deviate from the wild-type value at the serine 357 and double mutant transporters. At these two transporters, however, the Km of DA uptake increased, suggesting that the roles of serine 357 and serine 354 in substrate transport are different from their roles in binding. The K'm for induced efflux of DA decreased at the serine 357 mutant compared with the wild-type, whereas the K'm at the serine 354 mutant was the same as that of the wild-type. Further investigation of the role of substrate hydroxyls in the transport process revealed no difference between the transport of m-TYR or p-TYR, as measured indirectly through their induced efflux of DA, at any of the mutants. Although these serines are influential in inhibitor and substrate binding to the transporter and substrate uptake and efflux, they do not appear to be involved in a direct hydrogen bond interaction with substrate, suggesting that the pattern of distinct hydrogen bonding interactions at the beta-AR does not exist at the hNET. PMID:10428062

Danek Burgess, K S; Justice, J B

1999-08-01

302

PsTRXh1 and PsTRXh2 Are Both Pea h-Type Thioredoxins with Antagonistic Behavior in Redox Imbalances12  

PubMed Central

Thioredoxins (TRXs) are small ubiquitous oxidoreductases involved in disulfide bond reduction of a large panel of target proteins. The most complex cluster in the family of plant TRXs is formed by h-type TRXs. In Arabidopsis (Arabidopsis thaliana), nine members of this subgroup were described, which are less well known than their plastidial counterparts. The functional study of type-h TRXs is difficult because of the high number of isoforms and their similar biochemical characteristics, thus raising the question whether they have specific or redundant functions. Type-h TRXs are involved in seed germination and self incompatibility in pollen-pistil interaction. Their function as antioxidants has recently been proposed, but further work is needed to clarify this function in plants. In this study, we describe two new h-type TRXs from pea (Pisum sativum; stated PsTRXh1 and PsTRXh2). By functional complementation of a yeast (Saccharomyces cerevisiae) trx1? trx2? double mutant, we demonstrate that PsTRXh1 is involved in the redox-imbalance control, possibly through its interaction with peroxiredoxins. In contrast, PsTRXh2 provokes a phenotype of hypersensitivity to hydrogen peroxide in the yeast mutant. Furthermore, we show differential gene expression and protein accumulation of the two isoforms, PsTRXh1 protein being abundantly detected in vascular tissue and flowers, whereas PsTRXh2 gene expression was hardly detectable. By comparison with previous data of additional PsTRXh isoforms, our results indicate specific functions for the pea h-type TRXs so far described.

Traverso, Jose A.; Vignols, Florence; Cazalis, Roland; Pulido, Amada; Sahrawy, Mariam; Cejudo, Francisco Javier; Meyer, Yves; Chueca, Ana

2007-01-01

303

iPS cells to model CDKL5-related disorders  

PubMed Central

Rett syndrome (RTT) is a progressive neurologic disorder representing one of the most common causes of mental retardation in females. To date mutations in three genes have been associated with this condition. Classic RTT is caused by mutations in the MECP2 gene, whereas variants can be due to mutations in either MECP2 or FOXG1 or CDKL5. Mutations in CDKL5 have been identified both in females with the early onset seizure variant of RTT and in males with X-linked epileptic encephalopathy. CDKL5 is a kinase protein highly expressed in neurons, but its exact function inside the cell is unknown. To address this issue we established a human cellular model for CDKL5-related disease using the recently developed technology of induced pluripotent stem cells (iPSCs). iPSCs can be expanded indefinitely and differentiated in vitro into many different cell types, including neurons. These features make them the ideal tool to study disease mechanisms directly on the primarily affected neuronal cells. We derived iPSCs from fibroblasts of one female with p.Q347X and one male with p.T288I mutation, affected by early onset seizure variant and X-linked epileptic encephalopathy, respectively. We demonstrated that female CDKL5-mutated iPSCs maintain X-chromosome inactivation and clones express either the mutant CDKL5 allele or the wild-type allele that serve as an ideal experimental control. Array CGH indicates normal isogenic molecular karyotypes without detection of de novo CNVs in the CDKL5-mutated iPSCs. Furthermore, the iPS cells can be differentiated into neurons and are thus suitable to model disease pathogenesis in vitro.

Amenduni, Mariangela; De Filippis, Roberta; Cheung, Aaron Y L; Disciglio, Vittoria; Epistolato, Maria Carmela; Ariani, Francesca; Mari, Francesca; Mencarelli, Maria Antonietta; Hayek, Youssef; Renieri, Alessandra; Ellis, James; Meloni, Ilaria

2011-01-01

304

A serine elastase inhibitor reduces inflammation and fibrosis and preserves cardiac function after experimentally-induced murine myocarditis  

Microsoft Academic Search

In viral myocarditis, inflammation and destruction of cardiac myocytes leads to fibrosis, causing progressive impairment in cardiac function. Here we show the etiologic importance of serine elastase activity in the pathophysiology of acute viral myocarditis and the therapeutic efficacy of an elastase inhibitor. In DBA\\/2 mice inoculated with the encephalomyocarditis virus, a more than 150% increase in myocardial serine elastase

Jong K. Lee; Syed H. E. Zaidi; Peter Liu; Fayez Dawood; Alexander Y. L. Cheah; Wen-Hu Wen; Yuriko Saiki; Marlene Rabinovitch

1998-01-01

305

Expression and location of phospho-Artemis (Serine516) in hair follicles during induced growth of mouse hair.  

PubMed

Artemis has been implicated in having a role in NHEJ, and it is also a multifunctional protein. Previous studies have found Omenn syndrome-like phenotype due to Artemis mutations and associated with alopecia. As Artemis phosphorylation in its c-terminus including Serine516 is prerequisite for the Artemis endonuclease reaction, we postulate that Artemis (Serine516) may be expressed in hair follicle and relate to hair cycling. In this study, hair growth in C57BL/6 mice was induced by plucking the telogen hair on the back. Expression of Artemis (Serine516) in hair follicles during the hair growth cycle was evaluated by immunofluorescence using cryosections and a specific polyclonal anti-Artemis (Serine516) immunoglobulin G (IgG) antibody. It was detected in germ cells, cap, and club hair adjoining the epidermis in telogen. In anagen II, intense staining for Artemis (Serine516) was found in the whole interfollicular epidermis, and in strand keratinocytes. In anagen IV, intense staining for Artemis (Serine516) was detected in basal cells and upper of outer root sheath (ORS) and inner root sheath (IRS). But only upper ORS and lower medulla were stained positive in anagen VI. Upper ORS and lower cortex were positively stained with Artemis (Serine516) in catagen. Based on the phenomenon that the expression of Artemis (Serine516) in mid-anagen and mature anagen was stronger than that in telogen and catagen, we suggest it may take roles in induced growth of mouse hair. PMID:22476261

Wu, Xian-Jie; Zhu, Jian-Wei; Liu, Hai; Lu, Zhong-Fa; Zheng, Min

2012-04-03

306

Increased in vivo phosphorylation of insulin receptor at serine 994 in the liver of obese insulin-resistant Zucker rats  

Microsoft Academic Search

Serine phosphorylation of the insulin receptor (IR) has been proposed to exert an inhibitory influence on its tyrosine kinase activity. Previous works using site-directed mutagenesis suggested that serine 994 of the IR (IR Ser 994) might be part of an inhibitory domain of the receptor. In this study we examined whether this residue is sub- jected to phosphorylation in vivo.

Marcelo P Coba; Marina C Muñoz; Fernando P Dominici; Jorge E Toblli; Clara Peña; Andrzej Bartke; Daniel Turyn

2004-01-01

307

Human DESC1 serine protease confers tumorigenic properties to MDCK cells and it is upregulated in tumours of different origin  

Microsoft Academic Search

Proteolysis of the extracellular matrix components plays a crucial role in the regulation of the cellular and physiological processes, and different pathologies have been associated with the loss or gain of function of proteolytic enzymes. DESC1 (differentially expressed in squamous cell carcinoma gene 1), a member of the TTSP (type II transmembrane serine protease) family of serine proteases, is an

C G Viloria; J R Peinado; A Astudillo; O García-Suárez; M V González; C Suárez; S Cal

2007-01-01

308

Competitive Activity-Based Protein Profiling Identifies Aza-?-Lactams as a Versatile Chemotype for Serine Hydrolase Inhibition  

PubMed Central

Serine hydrolases are one of the largest and most diverse enzyme classes in Nature. Most serine hydrolases lack selective inhibitors, which are needed for assigning functions to these enzymes. We recently discovered a set of aza-?-lactams (ABLs) that act as potent and selective inhibitors of the mammalian serine hydrolase protein-phosphatase methylesterase-1 (PME-1). The ABLs inactivate PME-1 by covalent acylation of the enzyme’s serine nucleophile, suggesting that they could offer a general scaffold for serine hydrolase inhibitor discovery. Here, we have tested this hypothesis by screening ABLs more broadly against cell and tissue proteomes by competitive activity-based protein profiling (ABPP), leading to the discovery of lead inhibitors for several serine hydrolases, including the uncharacterized enzyme alpha, beta-hydrolase-10 (ABHD10). ABPP-guided medicinal chemistry yielded a compound ABL303 that potently (IC50 value ~ 30 nM) and selectively inactivated ABHD10 in vitro and in living cells. A comparison of optimized inhibitors for PME-1 and ABHD10 indicates that modest structural changes that alter steric bulk can tailor the ABL to selectively react with distinct, sequence-unrelated serine hydrolases. Our findings, taken together, designate the ABL as a versatile reactive group for creating first-in-class serine hydrolase inhibitors.

Zuhl, Andrea M.; Mohr, Justin T.; Bachovchin, Daniel A.; Niessen, Sherry; Hsu, Ku-Lung; Berlin, Jacob M.; Dochnahl, Maximilian; Lopez-Alberca, Maria P.; Fu, Gregory C.; Cravatt, Benjamin F.

2012-01-01

309

Integration-Free iPS Cells Engineered Using Human Artificial Chromosome Vectors  

PubMed Central

Human artificial chromosomes (HACs) have unique characteristics as gene-delivery vectors, including episomal transmission and transfer of multiple, large transgenes. Here, we demonstrate the advantages of HAC vectors for reprogramming mouse embryonic fibroblasts (MEFs) into induced pluripotent stem (iPS) cells. Two HAC vectors (iHAC1 and iHAC2) were constructed. Both carried four reprogramming factors, and iHAC2 also encoded a p53-knockdown cassette. iHAC1 partially reprogrammed MEFs, and iHAC2 efficiently reprogrammed MEFs. Global gene expression patterns showed that the iHACs, unlike other vectors, generated relatively uniform iPS cells. Under non-selecting conditions, we established iHAC-free iPS cells by isolating cells that spontaneously lost iHAC2. Analyses of pluripotent markers, teratomas and chimeras confirmed that these iHAC-free iPS cells were pluripotent. Moreover, iHAC-free iPS cells with a re-introduced HAC encoding Herpes Simplex virus thymidine kinase were eliminated by ganciclovir treatment, indicating that the HAC safeguard system functioned in iPS cells. Thus, the HAC vector could generate uniform, integration-free iPS cells with a built-in safeguard system.

Hiratsuka, Masaharu; Uno, Narumi; Ueda, Kana; Kurosaki, Hajime; Imaoka, Natsuko; Kazuki, Kanako; Ueno, Etsuya; Akakura, Yutaro; Katoh, Motonobu; Osaki, Mitsuhiko; Kazuki, Yasuhiro; Nakagawa, Masato; Yamanaka, Shinya; Oshimura, Mitsuo

2011-01-01

310

Phase Transition and Mechanical Properties of PS/PVC/CdS Polymeric Nanocomposites  

NASA Astrophysics Data System (ADS)

The present study reports the phase transition temperature and mechanical properties of CdS dispersed PS-PVC nanocomposite through Dynamic Mechanical Analyzer (DMA). Thick films of polymeric nanocomposites have been synthesized by dispersing nano-filler particles of CdS in PS/PVC binary blend matrix. The surface morphology of PS/PVC blend samples has been characterized by Scanning Electron Microscopy (SEM) while the nanostructure of the CdS filler in PS/PVC/CdS composite has been ascertained through small angle X-ray Diffraction (XRD) technique. The phase transition temperature study of PS/PVC polymeric blends reveals that glass transition temperature, Tg, of the PS phase shifts towards lower temperature with the increase in PVC content in the blend whereas for CdS embedded polymeric phases of blends i.e. for PS/PVC/CdS samples, an increase in respective Tg values have been observed. This is suggestive to the fact that phase transition temperature and mechanical properties have been significantly influenced through the dispersion of CdS nano-filler particles in the studied polymeric blend series.

Mathur, Vishal; Dixit, Manasvi; Saxena, N. S.; Sharma, Kananbala

2010-06-01

311

Reprogramming in vivo produces teratomas and iPS cells with totipotency features.  

PubMed

Reprogramming of adult cells to generate induced pluripotent stem cells (iPS cells) has opened new therapeutic opportunities; however, little is known about the possibility of in vivo reprogramming within tissues. Here we show that transitory induction of the four factors Oct4, Sox2, Klf4 and c-Myc in mice results in teratomas emerging from multiple organs, implying that full reprogramming can occur in vivo. Analyses of the stomach, intestine, pancreas and kidney reveal groups of dedifferentiated cells that express the pluripotency marker NANOG, indicative of in situ reprogramming. By bone marrow transplantation, we demonstrate that haematopoietic cells can also be reprogrammed in vivo. Notably, reprogrammable mice present circulating iPS cells in the blood and, at the transcriptome level, these in vivo generated iPS cells are closer to embryonic stem cells (ES cells) than standard in vitro generated iPS cells. Moreover, in vivo iPS cells efficiently contribute to the trophectoderm lineage, suggesting that they achieve a more plastic or primitive state than ES cells. Finally, intraperitoneal injection of in vivo iPS cells generates embryo-like structures that express embryonic and extraembryonic markers. We conclude that reprogramming in vivo is feasible and confers totipotency features absent in standard iPS or ES cells. These discoveries could be relevant for future applications of reprogramming in regenerative medicine. PMID:24025773

Abad, María; Mosteiro, Lluc; Pantoja, Cristina; Cañamero, Marta; Rayon, Teresa; Ors, Inmaculada; Graña, Osvaldo; Megías, Diego; Domínguez, Orlando; Martínez, Dolores; Manzanares, Miguel; Ortega, Sagrario; Serrano, Manuel

2013-09-11

312

Evaluation of ECHO PS Positioning System in a Porcine Model of Simulated Laparoscopic Ventral Hernia Repair  

PubMed Central

Purpose. Operative efficiency improvements for laparoscopic ventral hernia repair (LVHR) have focused on reducing operative time while maintaining overall repair efficacy. Our objective was to evaluate procedure time and positioning accuracy of an inflatable mesh positioning device (Echo PS Positioning System), as compared to a standard transfascial suture technique, using a porcine model of simulated LVHR. Methods. The study population consisted of seventeen general surgeons (n = 17) that performed simulated LVHR on seventeen (n = 17) female Yorkshire pigs using two implantation techniques: (1) Ventralight ST Mesh + Echo PS Positioning System (Echo PS) and (2) Ventralight ST Mesh + transfascial sutures (TSs). Procedure time and mesh centering accuracy overtop of a simulated surgical defect were evaluated. Results. Echo PS demonstrated a 38.9% reduction in the overall procedure time, as compared to TS. During mesh preparation and positioning, Echo PS demonstrated a 60.5% reduction in procedure time (P < 0.0001). Although a trend toward improved centering accuracy was observed for Echo PS (16.2%), this was not significantly different than TS. Conclusions. Echo PS demonstrated a significant reduction in overall simulated LVHR procedure time, particularly during mesh preparation/positioning. These operative time savings may translate into reduced operating room costs and improved surgeon/operating room efficiency.

Hanna, Erin M.; Voeller, Guy R.; Roth, J. Scott; Scott, Jeffrey R.; Gagne, Darcy H.; Iannitti, David A.

2013-01-01

313

The Serine\\/Threonine\\/Tyrosine Phosphoproteome of the Model Bacterium Bacillus subtilis  

Microsoft Academic Search

Protein phosphorylation on serine, threonine, and tyrosine (Ser\\/Thr\\/Tyr) is well established as a key regulatory post- translational modification in eukaryotes, but little is known about its extent and function in prokaryotes. Although pro- tein kinases and phosphatases have been predicted and identified in a variety of bacterial species, classical bio- chemical approaches have so far revealed only a few sub-

Boris Macek; Ivan Mijakovic; Jesper V. Olsen; Florian Gnad; Chanchal Kumar; Peter R. Jensen; Matthias Mann

2007-01-01

314

Miniaturization and Validation of a High-Throughput Serine Kinase Assay Using the Alpha Screen Platform  

Microsoft Academic Search

Reducing costs while maintaining the highest readout quality is a precept of modern high-throughput screening. Given the trend toward nonradiometric screening platforms, this has been a big challenge for some kinase target classes. Common issues include lowsensitivity, susceptibility to nonspecific interference, or the need for costly reagents. In this study, the authors describe the feasibility ofminiaturization of a serine kinase

Achim Von Leoprechting; Renate Kumpf; Susanne Menzel; Dominique Reulle; Ralf Griebel; Martin J. Valler; Frank H. Büttner

2004-01-01

315

Pleiotrophin regulates serine phosphorylation and the cellular distribution of ?-adducin through activation of protein kinase C  

PubMed Central

Pleiotrophin (PTN) was found to regulate tyrosine phosphorylation of ?-adducin through the PTN/receptor protein tyrosine phosphatase (RPTP)?/? signaling pathway. We now demonstrate that PTN stimulates the phosphorylation of serines 713 and 726 in the myristoylated alanine-rich protein kinase (PK) C substrate domain of ?-adducin through activation of either PKC ? or ?. We also demonstrate that PTN stimulates translocation of phosphoserine 713 and 726 ?-adducin either to nuclei, where it associates with nuclear chromatin and with centrioles of dividing cells, or to a membrane-associated site, depending on the phase of cell growth. Furthermore, we demonstrate that PTN stimulates the degradation of ?-adducin in PTN-stimulated cells. Phosphorylation of serines 713 and 726 in ?-adducin is known to markedly reduce the affinity of ?-adducin for spectrin and actin and to uncouple actin/spectrin/?-adducin multimeric complexes needed for cytoskeletal stability. The data thus suggest that the PTN-stimulated phosphorylation of serines 713 and 726 in ?-adducin disrupts cytoskeletal protein complexes and integrity, features demonstrated in both PTN-stimulated cells and of highly malignant cells that constitutively express the endogenous Ptn gene. The data also support the important conclusion that PTN determines the cellular location of ?-adducin phosphorylated in serines 713 and 726 and raise the possibility that ?-adducin functions in support of structure of heterochromatin and centrioles during mitosis.

Pariser, Harold; Herradon, Gonzalo; Ezquerra, Laura; Perez-Pinera, Pablo; Deuel, Thomas F.

2005-01-01

316

Loss of hippocampal serine protease BSP1/neuropsin predisposes to global seizure activity.  

PubMed

Serine proteases in the adult CNS contribute both to activity-dependent structural changes accompanying learning and to the regulation of excitotoxic cell death. Brain serine protease 1 (BSP1)/neuropsin is a trypsin-like serine protease exclusively expressed, within the CNS, in the hippocampus and associated limbic structures. To explore the role of this enzyme, we have used gene targeting to disrupt this gene in mice. Mutant mice were viable and overtly normal; they displayed normal hippocampal long-term synaptic potentiation (LTP) and exhibited no deficits in spatial navigation (water maze). Nevertheless, electrophysiological studies revealed that the hippocampus of mice lacking this specifically expressed protease possessed an increased susceptibility for hyperexcitability (polyspiking) in response to repetitive afferent stimulation. Furthermore, seizure activity on kainic acid administration was markedly increased in mutant mice and was accompanied by heightened immediate early gene (c-fos) expression throughout the brain. In view of the regional selectivity of BSP1/neuropsin brain expression, the observed phenotype may selectively reflect limbic function, further implicating the hippocampus and amygdala in controlling cortical activation. Within the hippocampus, our data suggest that BSP1/neuropsin, unlike other serine proteases, has little effect on physiological synaptic remodeling and instead plays a role in limiting neuronal hyperexcitability induced by epileptogenic insult. PMID:11549709

Davies, B; Kearns, I R; Ure, J; Davies, C H; Lathe, R

2001-09-15

317

Dysregulation of serine biosynthesis contributes to the growth defect of a Mycobacterium tuberculosis crp mutant  

PubMed Central

Summary Mycobacterium tuberculosis CRPMt, encoded by Rv3676 (crp), is a CRP-like transcription factor that binds with the serC – Rv0885 intergenic region. In the present study, we evaluated CRPMt’s regulation of serC and Rv0885 in M. tuberculosis and M. bovis BCG, using site-specific mutagenesis, promoter fusions and RT-PCR. The CRPMt binding site was required for full expression of serC and Rv0885, and expression of both genes was reduced in M. tuberculosis and M. bovis BCG crp mutants. These data show that CRPMt binding directly activates both serC and Rv0885 expression. M. tuberculosis serC restored the ability of an Escherichia coli serC mutant to grow in serine-dropout medium, demonstrating that M. tuberculosis serC encodes a phosphoserine aminotransferase. Serine supplementation, or overexpression of serC, accelerated the growth of M. tuberculosis and M. bovis BCG crp mutants in mycomedium, but not within macrophages. These results establish a role for CRPMt in the regulation of amino acid biosynthesis, and show that reduced serine production contributes to the slow-growth phenotype of M. tuberculosis and M. bovis BCG crp mutants in vitro. Restoration of serine biosynthesis by serC expression will facilitate identification of additional CRPMt-regulated factors required by M. tuberculosis during macrophage and host infection.

Bai, Guangchun; Schaak, Damen D.; Smith, Eric A.; McDonough, Kathleen A.

2013-01-01

318

Role of the Serine-Threonine Kinase PAK1 in Myxoma Virus Replication  

Microsoft Academic Search

Subversion or appropriation of cellular signal transduction pathways is a common strategy employed by viruses to promote an environment within infected cells that supports the viral replicative cycle. Using subsets of 3T3 murine fibroblasts previously shown to differ in their ability to support myxoma virus (MV) replication, we investigated the role of host serine-threonine kinases (STKs) as potential mediators of

J. B. Johnston; John W. Barrett; Wen Chang; Che-Sheng Chung; Wei Zeng; Jennefer Masters; Melissa Mann; Fuan Wang; Jingxin Cao; Grant McFadden

2003-01-01

319

ERK2 phosphorylation of serine 77 regulates Bmf pro-apoptotic activity.  

PubMed

B-cell lymphoma 2 (Bcl-2) homology 3 (BH3)-only proteins represent a class of pro-apoptotic factors that neutralize pro-survival Bcl-2 proteins, and, in some cases, directly activate Bax. The mechanisms of control and the role of BH3-only proteins, such as Bcl-2 like protein 11 extra large and Bad are well studied. By contrast, relatively little is known about the regulation and role of Bcl-2 modifying factor (Bmf). The B-RAF oncogene is mutated in ?8% of human tumors. We have previously shown that Bmf is upregulated at the transcript level and is required for apoptosis induced by targeting B-RAF signaling in tumor cells harboring mutant B-RAF. In this study, we show that Bmf is regulated at the post-translational level by mutant B-RAF-MEK-ERK2 signaling. Extracellular signal-regulated kinase (ERK2) directly phosphorylates Bmf on serine 74 and serine 77 residues with serine 77 being the predominant site. In addition, serine 77 phosphorylation reduces Bmf pro-apoptotic activity likely through a mechanism independent of altering Bmf localization to the mitochondria and/or interactions with dynein light chain 2 and the pro-survival proteins, B-cell lymphoma extra large, Bcl-2 and Mcl-1. These data identify a novel mode of regulation in Bmf that modulates its pro-apoptotic activity in mutant B-RAF tumor cells. PMID:22258404

Shao, Y; Aplin, A E

2012-01-19

320

Nonproteolytic serine proteinase homologs are involved in prophenoloxidase activation in the tobacco hornworm, Manduca sexta  

Microsoft Academic Search

In insects, the prophenoloxidase activation system is a defense mechanism against parasites and pathogens. Recognition of parasites or pathogens by pattern recognition receptors triggers activation of a serine proteinase cascade, leading to activation of prophenoloxidase-activating proteinase (PAP). PAP converts inactive prophenoloxidase (proPO) to active phenoloxidase (PO), which then catalyzes oxidation of phenolic compounds that can polymerize to form melanin. Because

Xiao-Qiang Yu; Haobo Jiang; Yang Wang; Michael R. Kanost

2003-01-01

321

In-silico comparative study of inhibitory mechanism of Plant Serine Proteinase Inhibitors  

PubMed Central

The nematodes like root-knot and cyst are plant-parasitic pest found in horticultural and agricultural crops. They do damages in the roots of plants as a result losses million tons of production. High cost of nematicides and environment safety concern has necessitated finding of some alternative methods. Under Integrated Pest Management (IPM) such problems are solving significantly by means of target gene inhibition, agrobacterium mediated transformation etc. One of this strategy use Plant Proteinase Inhibitors (PIs) gene which are used to control the proteolysis mechanism of Pest by inhibiting gut Serine Proteinase (SP). Present work investigates the utility of computer aided methods to study the mechanism of Protein-Protein interactions and thereby inhibition of Serine Proteinase by PIs. Hence 3D models of Serine Proteinase as well as Serine Proteinase Inhibitors (SPIs) generated using homology modeling. Validations of constructed models have been done by PROCHECK, VERIFY3D, ERRAT and PROSA. Prediction of Protein interacting surface patches and site specific protein docking was performed by using ZDOCK Server. Backbone refinement of output protein complexes was executed in Fiber Dock server. Interaction study between SP and SPIs complexes shows their comparative inhibition efficacy, measured in terms of number of hydrogen bonds, Van dar wall attraction and docking energy. This work reported that Vigna marina and Phaseolus oligospermus are having better inhibition efficiency in comparison to other inhibitors.

Siva Prasad, Chekkara Venkata Sathya; Gupta, Saurabh; Gaponenko, Alex; Dhar, Murli

2012-01-01

322

Crystal structure of bovine duodenase, a serine protease, with dual trypsin and chymotrypsin-like specificities.  

PubMed

The three-dimensional structure of duodenase, a serine protease from bovine duodenum mucosa, has been determined at 2.4A resolution. The enzyme, which has both trypsin-like and chymotrypsin-like activities, most closely resembles human cathepsin G with which it shares 57% sequence identity and similar specificity. The catalytic Ser195 in duodenase adopts the energetically favored conformation typical of serine proteinases and unlike the strained state typical of lipase/esterases. Of several waters in the active site of duodenase, the one associated with Ser214 is found in all serine proteinases and most lipase/esterases. The conservation of the Ser214 residue in serine proteinase, its presence in the active site, and participation in a hydrogen water network involving the catalytic triad (His57, Asp107, and Ser195) argues for its having an important role in the mechanism of action. It may be referred to as a fourth member of the catalytic triad. Duodenase is one of a growing family of enzymes that possesses trypsin-like and chymotrypsin-like activity. Not long ago, these activities were considered to be mutually exclusive. Computer modeling reveals that the S1 subsite of duodenase has structural features compatible with effective accommodation of P1 residues typical of trypsin (Arg/Lys) and chymotrypsin (Tyr/Phe) substrates. The determination of structural features associated with functional variation in the enzyme family may permit design of enzymes with a specific ratio of trypsin and chymotrypsin activities. PMID:10944388

Pletnev, V Z; Zamolodchikova, T S; Pangborn, W A; Duax, W L

2000-10-01

323

Importance of tetrahedral intermediate formation in the catalytic mechanism of the serine proteases chymotrypsin and subtilisin.  

PubMed

Two new inhibitors in which the terminal ?-carboxyl groups of Z-Ala-Ala-Phe-COOH and Z-Ala-Pro-Phe-COOH have been replaced with a proton to give Z-Ala-Ala-Phe-H and Z-Ala-Pro-Phe-H, respectively, have been synthesized. Using these inhibitors, we estimate that for ?-chymotrypsin and subtilisin Carlsberg the terminal carboxylate group decreases the level of inhibitor binding 3-4-fold while a glyoxal group increases the level of binding by 500-2000-fold. We show that at pH 7.2 the effective molarities of the catalytic hydroxyl group of the active site serine are 41000-229000 and 101000-159000 for ?-chymotrypsin and subtilisin Carlsberg, respectively. It is estimated that oxyanion stabilization and the increased effective molarity of the catalytic serine hydroxyl group can account for the catalytic efficiency of the reaction. We argue that substrate binding induces the formation of a strong hydrogen bond or low-barrier hydrogen bond between histidine-57 and aspartate-102 that increases the pK(a) of the active site histidine, allowing it to be an effective general base catalyst for the formation of the tetrahedral intermediate and increasing the effective molarity of the catalytic hydroxyl group of serine-195. A catalytic mechanism for acyl intermediate formation in the serine proteases is proposed. PMID:22757750

Petrillo, Teodolinda; O'Donohoe, Catrina A; Howe, Nicole; Malthouse, J Paul G

2012-07-25

324

The VA, VCD, Raman and ROA spectra of tri-L-serine in aqueous solution  

NASA Astrophysics Data System (ADS)

The structures of one conformer of the nonionic neutral and zwitterionic species of L-serinyl L-serinyl L-serine (SSS or tri-L-serine), together with its cationic and anionic species and the capped N-acetyl tri-L-serine N'-methylamide analog were optimized with density functional theory with the Becke 3LYP hybrid exchange correlation (XC) functional and the PW91 GGA XC functional and the 6-31G* and aug-cc-pVDZ basis sets. Subsequently, the vibrational absorption, vibrational circular dichroism, Raman and Raman optical activity spectra were simulated in order to compare them to experimentally measured spectra. In addition, we compare to previously reported studies for both structural determination and spectral simulations and measurements. A comparison of the various ways to treat the effects of the environment and solvation on both the structure and the spectral properties is thoroughly investigated for one conformer, with the goal to determine which level of theory is appropriate to use in the systematic search of the conformational space. In addition, the effects of the counterion, here Cl- anion, are also investigated. Here we present the current state of the art in nanobiology, where the latest methods in experimental and theoretical vibrational spectroscopy are used to gain useful information about the coupling of the nuclear, electronic and magnetic degrees of freedom and structure of tri-L-serine and its capped peptide analog with the environment.

Jürgensen, V. Würtz; Jalkanen, K.

2006-03-01

325

Isolation and Properties of Stachyrase A, a Chymotrypsin-Like Serine Proteinase from Stachybotrys chartarum  

PubMed Central

A strain of the common mold Stachybotrys chartarum has been isolated from the lung of a child with pulmonary hemorrhage. We report the purification of stachyrase A, a new serine chymotrypsin-like proteinase from S. chartarum. This enzyme cleaves major protease inhibitors, several biologically active peptides, and collagen, all of which are found in the lung.

Kordula, Tomasz; Banbula, Agnieszka; Macomson, Jeremy; Travis, James

2002-01-01

326

Long Distance Translocation of Sucrose, Serine, Leucine, Lysine, and Carbon Dioxide Assimilates  

PubMed Central

To determine the selectivity of movement of amino acids from source leaves to sink tissues in soybeans (Glycine max [L.] Merr. `Wells'), 14C-labeled serine, leucine, or lysine was applied to an abraded spot on a fully expanded trifoliolate leaflet, and an immature sink leaf three nodes above was monitored with a GM tube for arrival of radioactivity. Comparisons were made with 14C-sucrose and 14CO2 assimilates. Radioactivity was detected in the sink leaf for all compounds applied to the source leaflet. A heat girdle at the source leaf petiole essentially blocked movement of applied compounds, suggesting phloem transport. Transport velocities were similar (ranged from 0.75 to 1.06 cm/min), but mass transfer rates for sucrose were much higher than those for amino acids. Hence, the quantity of amino acids entering the phloem was much smaller than that of sucrose. Extraction of source, path, and sink tissues at the conclusion of the experiments revealed that 80 to 90% of the radioactivity remained in the source leaflet. Serine was partially metabolized in the transport path, whereas lysine and leucine were not. Although serine is found in greater quantities than leucine and lysine in the source leaf and path of soybeans, applied leucine and lysine were transported at comparable velocities and in only slightly lower quantities than was applied serine. Thus, no selective barrier against entry of these amino acids into the phloem exists.

Housley, Thomas L.; Peterson, David M.; Schrader, Larry E.

1977-01-01

327

Genome-wide survey of putative Serine\\/Threonine protein kinases in cyanobacteria  

Microsoft Academic Search

BACKGROUND: Serine\\/threonine kinases (STKs) have been found in an increasing number of prokaryotes, showing important roles in signal transduction that supplement the well known role of two-component system. Cyanobacteria are photoautotrophic prokaryotes able to grow in a wide range of ecological environments, and their signal transduction systems are important in adaptation to the environment. Sequence information from several cyanobacterial genomes

Xiaowen Zhang; Fangqing Zhao; Xiangyu Guan; Yu Yang; Chengwei Liang; Song Qin

2007-01-01

328

Mast cells limit extracellular levels of IL-13 via a serglycin proteoglycan-serine protease axis.  

PubMed

Mast cell (MC) granules contain large amounts of proteases of the chymase, tryptase and carboxypeptidase A (MC-CPA) type that are stored in complex with serglycin,a proteoglycan with heparin side chains. Hence, serglycinprotease complexes are released upon MC degranulation and may influence local inflammation. Here we explored the possibility that a serglycin-protease axis may regulate levels of IL-13, a cytokine involved in allergic asthma. Indeed, we found that wild-type MCs efficiently degraded exogenous or endogenously produced IL-13 upon degranulation,whereas serglycin ?/? MCs completely lacked this ability.Moreover, MC-mediated IL-13 degradation was blocked both by a serine protease inhibitor and by a heparin antagonist,which suggests that IL-13 degradation is catalyzed by serglycin-dependent serine proteases and that optimal IL-13 degradation is dependent on both the serglycin and the protease component of the serglycin-protease complex.Moreover, IL-13 degradation was abrogated in MC-CPA ?/?MC cultures, but was normal in cultures of MCs with an inactivating mutation of MC-CPA, which suggests that the IL-13-degrading serine proteases rely on MC-CPA protein.Together, our data implicate a serglycin-serine protease axis in the regulation of extracellular levels of IL-13. Reduction of IL-13 levels through this mechanism possibly can provide a protective function in the context of allergic inflammation. PMID:23667909

Waern, Ida; Karlsson, Iulia; Thorpe, Michael; Schlenner, Susan M; Feyerabend, Thorsten B; Rodewald, Hans-Reimer; Åbrink, Magnus; Hellman, Lars; Pejler, Gunnar; Wernersson, Sara

2012-12-01

329

Cysteine and serine protease inhibitors block intracellular development and disrupt the secretory pathway of Toxoplasma gondii  

Microsoft Academic Search

A number of cysteine and serine protease inhibitors blocked the intracellular growth and replication of Toxoplasma gondii tachyzoites. Most of these inhibitors caused only minor alterations to parasite morphology irrespective of the effects on the host cells. However, three, cathepsin inhibitor III, TPCK and subtilisin inhibitor III, caused extensive swelling of the secretory pathway of the parasite (i.e. the ER,

Michael K. Shaw; David S. Roos; Lewis G. Tilney

2002-01-01

330

Proteolytic Activation of Influenza Viruses by Serine Proteases TMPRSS2 and HAT from Human Airway Epithelium  

Microsoft Academic Search

Host cell proteases that cleave the hemagglutinin (HA) of influenza viruses in the human respiratory tract are still not identified. Here we cloned two human type II transmembrane serine proteases with known airway localization, TMPRSS2 and HAT, into mammalian expression vector. Cotransfection of mammalian cells with plasmids encoding HA and either protease resulted in HA cleavage in situ. Transient expression

Eva Bottcher; Tatyana Matrosovich; Michaela Beyerle; Hans-Dieter Klenk; Wolfgang Garten; Mikhail Matrosovich

2006-01-01

331

Serine racemase deletion disrupts memory for order and alters cortical dendritic morphology  

PubMed Central

There is substantial evidence implicating N-methyl-d-aspartate receptors (NMDARs) in memory and cognition. It has also been suggested that NMDAR hypofunction might underlie the cognitive deficits observed in schizophrenia since morphological changes, including alterations in the dendritic architecture of pyramidal neurons in the prefrontal cortex (PFC), have been reported in the schizophrenic brain post mortem. Here, we used a genetic model of NMDAR hypofunction, a serine racemase knockout (SR?/?) mouse in which the first coding exon of the mouse serine racemase gene has been deleted, to explore the role of d-serine in regulating cognitive functions as well as dendritic architecture. SR ?/? mice exhibited a significantly disrupted representation of the order of events in distinct experiences as revealed by object recognition and odor sequence tests; however, SR ?/? animals were unimpaired in the detection of novel objects and in spatial displacement, and showed intact relational memory in a test of transitive inference. In addition, SR ?/? mice exhibited normal sociability and preference for social novelty. Neurons in the medial PFC of SR?/? mice displayed reductions in the complexity, total length, and spine density of apical dendrites. These findings demonstrate that d-serine is important for specific aspects of cognition, as well as in regulating dendritic morphology of pyramidal neurons in the mPFC. Moreover, they suggest that NMDAR hypofunction might, in part, be responsible for the cognitive deficits and synaptic changes associated with schizophrenia, and highlight this signaling pathway as a potential target for therapeutic intervention.

DeVito, Loren M.; Balu, Darrick T.; Kanter, Benjamin R.; Lykken, Christine; Basu, Alo C.; Coyle, Joseph T.; Eichenbaum, Howard

2012-01-01

332

Reduction of Acute Alcoholic Intoxication by Alpha Amino Acids: Glycine and Serine.  

National Technical Information Service (NTIS)

The ability of glycine and of serine to protect rats from ethanol induced motor impairment was determined by pretreating the animals with these drugs, administering ethanol 30 minutes later, and evaluating the rats' performance on a rotor-rod test at 30 m...

K. Blum J. E. Wallace R. Friedman

1973-01-01

333

Inhibitor binding induces active site stabilization of the HCV NS3 protein serine protease domain  

PubMed Central

Few structures of viral serine proteases, those encoded by the Sindbis and Semliki Forest viruses, hepatitis C virus (HCV) and cytomegalovirus, have been reported. In the life cycle of HCV a crucial role is played by a chymotrypsin-like serine protease encoded at the N–terminus of the viral NS3 protein, the solution structure of which we present here complexed with a covalently bound reversible inhibitor. Unexpectedly, the residue in the P2 position of the inhibitor induces an effective stabilization of the catalytic His–Asp hydrogen bond, by shielding that region of the protease from the solvent. This interaction appears crucial in the activation of the enzyme catalytic machinery and represents an unprecedented observation for this family of enzymes. Our data suggest that natural substrates of this serine protease could contribute to the enzyme activation by a similar induced-fit mechanism. The high degree of similarity at the His–Asp catalytic site region between HCV NS3 and other viral serine proteases suggests that this behaviour could be a more general feature for this category of viral enzymes.

Barbato, G.; Cicero, D.O.; Cordier, F.; Narjes, F.; Gerlach, B.; Sambucini, S.; Grzesiek, S.; Matassa, V.G.; De Francesco, R.; Bazzo, R.

2000-01-01

334

Mice Deficient for the Type II Transmembrane Serine Protease, TMPRSS1\\/hepsin, Exhibit Profound Hearing Loss  

Microsoft Academic Search

Defective proteolysis has been implicated in hearing loss through the discovery of mutations causing autoso- mal recessive nonsyndromic deafness in a type II trans- membrane serine protease gene, TMPRSS3. To investi- gate their physiological function and the contribution of this family of proteases to the auditory function, we analyzed the hearing status of mice deficient for hepsin, also known as

Michel Guipponi; Justin Tan; Ping Z. F. Cannon; Lauren Donley; Pauline Crewther; Maria Clarke; Qingyu Wu; Robert K. Shepherd; Hamish S. Scott

2007-01-01

335

Genomic structure and expression analyses of serine acetyltransferase gene in Citrullus vulgaris (watermelon)  

Microsoft Academic Search

The genomic clones of Sat gene encoding serine acetyltransferase (SATase), a key enzyme in cysteine biosynthesis in plants, were isolated from the genomic library of Citrullus vulgaris (watermelon). The determination of nucleotide sequence of 5.7 kilobase pair (kbp) length revealed the presence of two introns of 1939 basepair (bp) and 515 bp length in the gene. The transcription start point

Kazuki Saito; Kenji Inoue; Rumiko Fukushima; Masaaki Noji

1997-01-01

336

Serine/threonine protein phosphatases: multi-purpose enzymes in control of defense mechanisms  

Technology Transfer Automated Retrieval System (TEKTRAN)

Serine/threonine protein phosphatases are a group of enzymes involved in the regulation of defense mechanisms in plants. This paper describes the effects of an inhibitor of these enzymes on the expression of all of the genes associated with these defense mechanisms. The results suggest that inhibi...

337

Relationships Between Educator Beliefs, Perceptions of Educational Practices and Skills, PS\\/RtI Implementation, and Educational Outcomes  

Microsoft Academic Search

This study examined the relationships between pilot school status and Problem-Solving\\/Response to Intervention (PS\\/RtI) implementation, educator variables and PS\\/RtI implementation, and PS\\/RtI implementation and student and systemic outcomes following the final year of a 3-year PS\\/RtI implementation Project. School-Based Leadership Team (SBLT) members from 34 pilot schools in seven demonstration districts received training, as well as ongoing technical assistance and

Kevin Stockslager

2011-01-01

338

Hepatitis C virus NS3 serine proteinase: trans-cleavage requirements and processing kinetics.  

PubMed Central

The hepatitis C virus H strain (HCV-H) polyprotein is cleaved to produce at least 10 distinct products, in the order of NH2-C-E1-E2-p7-NS2-NS3-NS4A-NS4B-NS5A-NS5B -COOH. An HCV-encoded serine proteinase activity in NS3 is required for cleavage at four sites in the nonstructural region (3/4A, 4A/4B, 4B/5A, and 5A/5B). In this report, the HCV-H serine proteinase domain (the N-terminal 181 residues of NS3) was tested for its ability to mediate trans-processing at these four sites. By using an NS3-5B substrate with an inactivated serine proteinase domain, trans-cleavage was observed at all sites except for the 3/4A site. Deletion of the inactive proteinase domain led to efficient trans-processing at the 3/4A site. Smaller NS4A-4B and NS5A-5B substrates were processed efficiently in trans; however, cleavage of an NS4B-5A substrate occurred only when the serine proteinase domain was coexpressed with NS4A. Only the N-terminal 35 amino acids of NS4A were required for this activity. Thus, while NS4A appears to be absolutely required for trans-cleavage at the 4B/5A site, it is not an essential cofactor for serine proteinase activity. To begin to examine the conservation (or divergence) of serine proteinase-substrate interactions during HCV evolution, we demonstrated that similar trans-processing occurred when the proteinase domains and substrates were derived from two different HCV subtypes. These results are encouraging for the development of broadly effective HCV serine proteinase inhibitors as antiviral agents. Finally, the kinetics of processing in the nonstructural region was examined by pulse-chase analysis. NS3-containing precursors were absent, indicating that the 2/3 and 3/4A cleavages occur rapidly. In contrast, processing of the NS4A-5B region appeared to involve multiple pathways, and significant quantities of various polyprotein intermediates were observed. NS5B, the putative RNA polymerase, was found to be significantly less stable than the other mature cleavage products. This instability appeared to be an inherent property of NS5B and did not depend on expression of other viral polypeptides, including the HCV-encoded proteinases. Images

Lin, C; Pragai, B M; Grakoui, A; Xu, J; Rice, C M

1994-01-01

339

Dynamic dipole polarizabilities of H- and Ps- in weakly coupled plasmas  

NASA Astrophysics Data System (ADS)

The effects of weakly coupled plasmas on the dynamic dipole polarizabilities of the H- and Ps- ions are investigated using highly correlated exponential wave functions. The Debye-Hückel shielding approach of plasma modeling is used to represent weakly coupled plasma environments. In free-atomic cases, results obtained from the present study for H- are in agreement with the available calculations and results for Ps- are reported for the first time. Frequency-dependent polarizabilities of H- and Ps- as functions of screening parameter are also presented for the first time.

Kar, Sabyasachi; Li, H. W.; Jiang, Pinghui

2013-08-01

340

pS2 (TFF1) expression in prostate carcinoma: correlation with steroid receptor status.  

PubMed

pS2 or TFF1 is a member of the trefoil factor family, which is distributed throughout the gastrointestinal tract in both normal and diseased tissues. It is also considered to be one of the major estrogen-regulated proteins and an indicator of estrogen receptor (ER) functionality. pS2 has previously been investigated in benign and malignant prostate lesions with little information about its relationship to steroid receptor status. Our purpose was to correlate pS2 expression with steroid receptor status (ER alpha and progesterone receptor (PR)) and other pathologic variables in prostate carcinoma. 15 benign prostate hyperplasia (BPH) and 47 prostate carcinoma cases were investigated by means of immunohistochemistry for pS2, ER and PR expression. 80% of BPH showed pS2 cytoplasmic immunoreactivity in hyperplastic acini and about half of these cases also exhibited nuclear staining decorating basal or both basal and luminal nuclei. pS2 was highly expressed in prostate carcinoma (91.4%) with both cytoplasmic and nuclear patterns of staining. The latter pattern was significantly associated with carcinoma having a low Gleason score (p=0.02). pS2 lacked any significant correlation with steroid receptor status, stage or grade. Univariate survival analysis revealed a significant impact of stage (p=0.03) and nodal status (p<0.0001) on patient outcome. The diagnostic value of pS2 expression in prostate carcinoma validated 74.19% accuracy, 91.48% sensitivity and 78.18% positive predictive value. The high sensitivity of pS2 expression in prostate carcinoma could make it a suitable marker for diagnosis of prostate carcinoma, especially in metastatic cases of unknown origin. The absence of correlation and dissimilarity in immunolocalization between pS2 and ER alpha leads to the assumption that ER alpha could not be the regulatory protein for pS2 and may raise questions about the functionality of ER alpha in prostate. The nuclear pattern of pS2 immunoreactivity either in benign or malignant prostatic lesions is similar to the published data on ER beta distribution and could also identify a subset of carcinoma patients with a favorable prognosis. PMID:19132993

Abdou, Asmaa Gaber; Aiad, Hayam Abdel Samie; Sultan, Sultan Mohamed

2008-11-01

341

Room temperature light emission from the low-dimensional semiconductors AZrPS{sub 6} ( A = K, Rb, Cs).  

SciTech Connect

The new semiconducting thiophosphate compounds KZrPS{sub 6}, RbZrPS{sub 6}, and CsZrPS{sub 6} exhibit red light emission at room temperature. The materials have longer photoluminescence lifetimes than most of the inorganic chalcogenide semiconductors. They can be solution processed into thin films for potential device fabrication.

Banerjee, S.; Szarko, J. M.; Yuhas, B. D.; Malliakas, C. D.; Chen, L. X.; Kanatzidis, M. G. (Materials Science Division); (Northwestern Univ.)

2010-03-29

342

Roscovitine Inhibits EBNA1 Serine 393 Phosphorylation, Nuclear Localization, Transcription, and Episome Maintenance? †  

PubMed Central

Latent Epstein-Barr virus (EBV) infection causes human lymphomas and carcinomas. EBV usually persists as an episome in malignant cells. EBV episome persistence, replication, and gene expression are dependent on EBNA1 binding to multiple cognate sites in oriP. To search for inhibitors of EBNA1- and oriP-dependent episome maintenance or transcription, a library of 40,550 small molecules was screened for compounds that inhibit EBNA1- and oriP-dependent transcription and do not inhibit EBNA1- and oriP-independent transcription. This screening identified roscovitine, a selective inhibitor of cyclin-dependent kinase 1 (CDK1), CDK2, CDK5, and CDK7. Based on motif predictions of EBNA1 serine 393 as a CDK phosphorylation site and 486RALL489 and 580KDLVM584 as potential cyclin binding domains, we hypothesized that cyclin binding to EBNA1 may enable CDK1, -2, -5, or -7 to phosphorylate serine 393. We found that Escherichia coli-expressed EBNA1 amino acids 387 to 641 were phosphorylated in vitro by CDK1-, -2-, -5-, and -7/cyclin complexes and serine 393 phosphorylation was roscovitine inhibited. Further, S393A mutation abrogated phosphorylation. S393A mutant EBNA1 was deficient in supporting EBNA1- and oriP-dependent transcription and episome persistence, and roscovitine had little further effect on the diminished S393A mutant EBNA1-mediated transcription or episome persistence. Immunoprecipitated FLAG-EBNA1 was phosphorylated in vitro, and roscovitine inhibited this phosphorylation. Moreover, roscovitine decreased nuclear EBNA1 and often increased cytoplasmic EBNA1, whereas S393A mutant EBNA1 was localized equally in the nucleus and cytoplasm and was unaffected by roscovitine treatment. These data indicate that roscovitine effects are serine 393 specific and that serine 393 is important in EBNA1- and oriPCp-dependent transcription and episome persistence.

Kang, Myung-Soo; Lee, Eun Kyung; Soni, Vishal; Lewis, Timothy A.; Koehler, Angela N.; Srinivasan, Viswanathan; Kieff, Elliott

2011-01-01

343

In Vivo Role of Alternative Splicing and Serine Phosphorylation of the Microphthalmia-Associated Transcription Factor  

PubMed Central

The microphthalmia-associated transcription factor (MITF) is a basic helix-loop-helix leucine zipper protein that plays major roles in the development and physiology of vertebrate melanocytes and melanoma cells. It is regulated by post-translational modifications, including phosphorylation at serine 73, which based on in vitro experiments imparts on MITF an increased transcriptional activity paired with a decreased stability. Serine 73 is encoded by the alternatively spliced exon 2B, which is preferentially skipped in mice carrying a targeted serine-73-to-alanine mutation. Here, we measured the relative abundance of exon 2B+ and exon 2B? RNAs in freshly isolated and FACS-sorted wild-type melanoblasts and melanocytes and generated a series of knock-in mice allowing forced incorporation of either alanine, aspartate, or wild-type serine at position 73. None of these knock-in alleles, however, creates a striking pigmentation phenotype on its own, but differences between them can be revealed either by a general reduction of Mitf transcript levels or in heteroallelic combinations with extant Mitf mutations. In fact, compared with straight serine-73 knock-in mice with their relative reduction of 2B+ Mitf, forced incorporation of alanine 73 leads to greater increases in MITF protein levels, melanoblast and melanocyte numbers, and extent of pigmentation in particular allelic combinations. These results underscore, in vivo, the importance of the link between alternative splicing and post-translational modifications and may bear on the recent observation that exon 2B skipping can be found in metastatic melanoma.

Debbache, Julien; Raza Zaidi, M.; Davis, Sean; Guo, Theresa; Bismuth, Keren; Wang, Xin; Skuntz, Susan; Maric, Dragan; Pickel, James; Meltzer, Paul; Merlino, Glenn; Arnheiter, Heinz

2012-01-01

344

Compact integrated tunable chromatic dispersion compensator with a 4000 ps\\/nm tuning range  

Microsoft Academic Search

A +\\/-2000 ps\\/nm continuous tuning range with low group delay ripple was demonstrated for 10 Gb\\/s NRZ signals using ring resonator allpass filters with diameters of 2 mm in silica-on-silicon planar waveguides.

C. K. Madsen; S. Chandrasekhar; E. J. Laskowski; K. Bogart; M. A. Cappuzzo; A. Paunescu; L. W. Stulz; L. T. Gomez

2001-01-01

345

Study of Neutron Induced Defects in Ceramics using the GiPS Facility  

NASA Astrophysics Data System (ADS)

Preliminary results are presented from a study of neutron irradiation damage in Sapphire and B4C, produced with a fluence of 6×1018 n/cm2 and ~1015 n/cm2, respectively. Measurements were performed at the GiPS facility and the SPONSOR beam at HZDR, and in the PAL spectrometer at NRCN. Bulk and vacancies lifetimes were identified in the Sapphire, ~150ps and ~188ps, respectively, with complete trapping in the irradiation induced vacancies. Irradiation damage in B4C found to be limited to the surface. A single lifetime of ~166ps was measured in both irradiated and non-irradiated samples, and was associated with the bulk.

May-Tal Beck, S.; Butterling, M.; Anwand, W.; Beck, A.; Wagner, A.; Brauer, G.; Ocherashvili, A.; Israelashvili, I.; Hen, O.

2013-06-01

346

Molecular Pathways Governing Development of Vascular Endothelial Cells from ES/iPS Cells.  

PubMed

Assembly of complex vascular networks occurs in numerous biological systems through morphogenetic processes such as vasculogenesis, angiogenesis and vascular remodeling. Pluripotent stem cells such as embryonic stem (ES) and induced pluripotent stem (iPS) cells can differentiate into any cell type, including endothelial cells (ECs), and have been extensively used as in vitro models to analyze molecular mechanisms underlying EC generation and differentiation. The emergence of these promising new approaches suggests that ECs could be used in clinical therapy. Much evidence suggests that ES/iPS cell differentiation into ECs in vitro mimics the in vivo vascular morphogenic process. Through sequential steps of maturation, ECs derived from ES/iPS cells can be further differentiated into arterial, venous, capillary and lymphatic ECs, as well as smooth muscle cells. Here, we review EC development from ES/iPS cells with special attention to molecular pathways functioning in EC specification. PMID:23765563

Tan, Keai Sinn; Tamura, Kiyomi; Lai, Mei I; Veerakumarasivam, Abhimanyu; Nakanishi, Yoichi; Ogawa, Minetaro; Sugiyama, Daisuke

2013-10-01

347

Chemically defined conditions for human iPS cell derivation and culture  

PubMed Central

We reexamine the individual components for human ES and iPS cell culture, and formulate a cell culture system in which all protein reagents for liquid media, attachment surfaces, and splitting are chemically defined. A major improvement is the lack of a serum albumin component, as variations in either animal or human sourced albumin batches have previously plagued human ES and iPS cell culture with inconsistencies. Using this new medium (E8) and vitronectin-coated surfaces, we demonstrate improved derivation efficiencies of vector-free human iPS cells with an episomal approach. This simplified E8 medium should facilitate both the research use and clinical applications of human ES and iPS cells and their derivatives, and should be applicable to other reprogramming methods.

Chen, Guokai; Gulbranson, Daniel R.; Hou, Zhonggang; Bolin, Jennifer M.; Ruotti, Victor; Probasco, Mitchell D.; Smuga-Otto, Kimberly; Howden, Sara E.; Diol, Nicole R.; Propson, Nicholas E.; Wagner, Ryan; Lee, Garrett O.; Antosiewicz-Bourget, Jessica; Teng, Joyce M. C.; Thomson, James A.

2011-01-01

348

7 CFR 1753.37 - Plans and specifications (P&S).  

Code of Federal Regulations, 2010 CFR

...proposal. (2) Guidelines for the preparation of the detailed equipment specifications are contained in the Telecommunications Engineering and Construction Manual (TE&CM), which is available from RUS. (c) RUS review of P&S is...

2010-01-01

349

7 CFR 1753.37 - Plans and specifications (P&S).  

Code of Federal Regulations, 2010 CFR

...proposal. (2) Guidelines for the preparation of the detailed equipment specifications are contained in the Telecommunications Engineering and Construction Manual (TE&CM), which is available from RUS. (c) RUS review of P&S is...

2009-01-01

350

76 FR 35683 - Medicare Program; Conditions of Participation (CoPs) for Community Mental Health Centers  

Federal Register 2010, 2011, 2012, 2013

...117 June 17, 2011 Part V Department of Health and Human Services...Participation (CoPs) for Community Mental Health Centers; Proposed Rule Federal Register...DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for...

2011-06-17

351

Cardiomyocyte Contractile Dysfunction in the APPswe/PS1dE9 Mouse Model of Alzheimer's Disease  

PubMed Central

Objectives Ample clinical and experimental evidence indicated that patients with Alzheimer's disease display a high incidence of cardiovascular events. This study was designed to examine myocardial histology, cardiomyocyte shortening, intracellular Ca2+ homeostasis and regulatory proteins, electrocardiogram, adrenergic response, endoplasmic reticulum (ER) stress and protein carbonyl formation in C57 wild-type (WT) mice and an APPswe/PS1dE9 transgenic (APP/PS1) model for Alzheimer's disease. Methods Cardiomyocyte mechanical properties were evaluated including peak shortening (PS), time-to-PS (TPS), time-to-relengthening (TR), maximal velocity of shortening and relengthening (±dL/dt), intracellular Ca2+ transient rise and decay. Results Little histological changes were observed in APP/PS1 myocardium. Cardiomyocytes from APP/PS1 but not APP or PS1 single mutation mice exhibited depressed PS, reduced±dL/dt, normal TPS and TR compared with WT mice. Rise in intracellular Ca2+ was lower accompanied by unchanged resting/peak intracellular Ca2+ levels and intracellular Ca2+ decay in APP/PS1 mice. Cardiomyocytes from APP/PS1 mice exhibited a steeper decline in PS at high frequencies. The responsiveness to adrenergic agonists was dampened although ?1-adrenergic receptor expression was unchanged in APP/PS1 hearts. Expression of the Ca2+ regulatory protein phospholamban and protein carbonyl formation were downregulated and elevated, respectively, associated with unchanged SERCA2a, Na+-Ca2+ exchanger and ER stress markers in APP/PS1 hearts. Our further study revealed that antioxidant N-acetylcysteine attenuated the contractile dysfunction in APP/PS1 mice. Conclusions Our results depicted overt cardiomyocyte mechanical dysfunction in the APP/PS1 Alzheimer's disease model, possibly due to oxidative stress.

Turdi, Subat; Guo, Rui; Huff, Anna F.; Wolf, Eliza M.; Culver, Bruce; Ren, Jun

2009-01-01

352

Characterization of in vivo MRI detectable thalamic amyloid plaques from APP\\/PS1 mice  

Microsoft Academic Search

Amyloid deposits are one of the hallmarks of Alzheimer's disease. Recent studies, in transgenic mice modeling Alzheimer's disease showed that, using in vivo, contrast agent-free, MRI, thalamic amyloid plaques are more easily detected than other plaques of the brain. Our study evaluated the characteristics of these thalamic plaques in a large population of APP\\/PS1, PS1 and C57BL\\/6 mice. Thalamic spots

Marc Dhenain; Nadine El Tannir El Tayara; Ting-Di Wu; Maryvonne Guégan; Andreas Volk; Carmen Quintana; Benoît Delatour

2009-01-01

353

In vivo MRI and histological evaluation of brain atrophy in APP\\/PS1 transgenic mice  

Microsoft Academic Search

Regional cerebral atrophy was evaluated in APP\\/PS1 mice harboring mutated transgenes linked to familial Alzheimer's disease, using complementary methods. In vivo high resolution MRI was selected for measurements of brain atrophy and associated cerebrospinal fluid dilation; histological analysis was performed to reveal localized atrophies and to evaluate amyloid burden.Young APP\\/PS1 mice examined at a pre-amyloid stage (10 weeks) showed disruption

Benoît Delatour; Maryvonne Guégan; Andreas Volk; Marc Dhenain

2006-01-01

354

Multi-frame x-ray imaging with a large area 40ps camera  

SciTech Connect

The authors have developed a large area short pulse framing camera that is capable of sixteen frames and shutter times of 40ps per frame. This is accomplished with a high fidelity electrical circuit and a L/D = 20 microchannel plate, driven by a short pulse (80ps) high amplitude electrical driver. They show results of this work they have done to support this type of shutter time and the difficulties associated with large area high speed shuttering.

Bell, P.M.; Kilkenny, J.D.; Landen, O.L.; Hanks, R.L.; Wiedwald, J.D. [Lawrence Livermore National Lab., CA (US); Bradley, D.K. [Univ. of Rochester, NY (US). Lab. for Laser Energetics

1992-11-09

355

Interpolating time counter with 100 ps resolution on a single FPGA device  

Microsoft Academic Search

This paper describes the logic and performance of an interpolating time counter integrated on a single FPGA device. The resolution of 100 ps (LSB) was obtained because of the new design of the FPGA delay lines used for precise time-to-digital conversion, and the use of enhanced CMOS FPGA technology. The worst-case random error of 170 ps has been lowered to

Ryszard Szplet; Jozef Kalisz; Rafal Szymanowski

2000-01-01

356

Synthesis of core–shell structured PS\\/Fe 3O 4 microbeads and their magnetorheology  

Microsoft Academic Search

Most magnetic materials possess serious sedimentation problem due to their large density when they are adopted as magnetorheological (MR) materials. In this communication, we fabricated novel core–shell structured polystyrene(PS)\\/Fe3O4 microbeads via a facile method. Porous morphology of the PS obtained by etching silica particles and the loaded Fe3O4 was observed via both SEM and TEM images. XRD pattern confirms crystalline

Fei Fei Fang; Ji Hye Kim; Hyoung Jin Choi

2009-01-01

357

PS-InSAR time series analysis as a tool for measuring landslide dynamics  

Microsoft Academic Search

PS-InSAR analysis is today a widely accepted methodology for the accurate measurement of ground displacements related to processes with slow kinematics, such as ground settlement, subsidence, uplift and slow moving landslides. The advanced use of PS-InSAR information has, however, very promising potential also for the understanding of the landslide behavior in time and to study the correlations between such dynamics

V. Pancioli; P. Lu; F. Catani; F. Cigna

2009-01-01

358

Head-tail instability and microwave instability in the KEK-PS  

SciTech Connect

Head-tail instability and microwave instability has been studied and cured in the course of the intensity up-grade program of the KEK-PS. Experimental results, its interpretations and cures are given on the head-tail instabilities, emerging just after the acceleration start, and the microwave instability, arising after the transition energy in the 12 GeV PS main ring.

Toyama, T.; Arakawa, D.; Igarashi, S.; Kishiro, J.; Koba, K.; Nakamura, E.; Takayama, K.; Yoshii, M. [KEK, High Energy Accelerator Research Organization 1-1 Oho, Tsukuba-shi, Ibaraki-ken 305-0801 (Japan)

1999-12-03

359

Lead ion beam emittance and transmission studies in the PS-SPS complex at CERN  

Microsoft Academic Search

In the Lead Ion Facility at CERN [1] Pb53+ ion beams are accelerated up to a kinetic energy of 4.2 GeV\\/u in the CERN PS, extracted and stripped to Pb82+ in the transfer line from PS to SPS where they are injected and accelerated up to 157 GeV\\/u. The stripping efficiency, emittance growth and energy loss in Al strippers of

Gianluigi Arduini; R. Bailey; T. Bohl; H. Burkhardt; R. Cappi; C. Carter; Karel Cornelis; M. Dach; G. de Rijk; A. Faugier; G. Ferioli; H. Jakob; M. Jonker; Django Manglunki; G. Martini; M. Martini; J. P. Riunaud; C. Scheidenberger; B. Vandorpe; L. Vos; M. Zanolli

1996-01-01

360

Blends of PS with SBR Devulcanized By Ultrasound: Rheology and Morphology  

Microsoft Academic Search

The rheological properties and the morphology of blends of styrene-butadiene rubber (SBR), devulcanizated by ultrasound (dSBR), with polystyrene (PS) were studied. A compatibilizer, a styrene-butadiene block copolymer (SBS) was also added to dSBR\\/PS blends. The shear viscosity at low and high shear rates, the complex dynamic viscosity and the creep behavior were measured. It was observed that the addition of

C. H. Scuracchio; R. E. S. Bretas; A. I. Isayev

2004-01-01

361

Pyruvate kinase M2 promotes de novo serine synthesis to sustain mTORC1 activity and cell proliferation  

PubMed Central

Despite the fact that most cancer cells display high glycolytic activity, cancer cells selectively express the less active M2 isoform of pyruvate kinase (PKM2). Here we demonstrate that PKM2 expression makes a critical regulatory contribution to the serine synthetic pathway. In the absence of serine, an allosteric activator of PKM2, glycolytic efflux to lactate is significantly reduced in PKM2-expressing cells. This inhibition of PKM2 results in the accumulation of glycolytic intermediates that feed into serine synthesis. As a consequence, PKM2-expressing cells can maintain mammalian target of rapamycin complex 1 activity and proliferate in serine-depleted medium, but PKM1-expressing cells cannot. Cellular detection of serine depletion depends on general control nonderepressible 2 kinase-activating transcription factor 4 (GCN2-ATF4) pathway activation and results in increased expression of enzymes required for serine synthesis from the accumulating glycolytic precursors. These findings suggest that tumor cells use serine-dependent regulation of PKM2 and GCN2 to modulate the flux of glycolytic intermediates in support of cell proliferation.

Ye, Jiangbin; Mancuso, Anthony; Tong, Xuemei; Ward, Patrick S.; Fan, Jing; Rabinowitz, Joshua D.; Thompson, Craig B.

2012-01-01

362

Pyruvate kinase M2 promotes de novo serine synthesis to sustain mTORC1 activity and cell proliferation.  

PubMed

Despite the fact that most cancer cells display high glycolytic activity, cancer cells selectively express the less active M2 isoform of pyruvate kinase (PKM2). Here we demonstrate that PKM2 expression makes a critical regulatory contribution to the serine synthetic pathway. In the absence of serine, an allosteric activator of PKM2, glycolytic efflux to lactate is significantly reduced in PKM2-expressing cells. This inhibition of PKM2 results in the accumulation of glycolytic intermediates that feed into serine synthesis. As a consequence, PKM2-expressing cells can maintain mammalian target of rapamycin complex 1 activity and proliferate in serine-depleted medium, but PKM1-expressing cells cannot. Cellular detection of serine depletion depends on general control nonderepressible 2 kinase-activating transcription factor 4 (GCN2-ATF4) pathway activation and results in increased expression of enzymes required for serine synthesis from the accumulating glycolytic precursors. These findings suggest that tumor cells use serine-dependent regulation of PKM2 and GCN2 to modulate the flux of glycolytic intermediates in support of cell proliferation. PMID:22509023

Ye, Jiangbin; Mancuso, Anthony; Tong, Xuemei; Ward, Patrick S; Fan, Jing; Rabinowitz, Joshua D; Thompson, Craig B

2012-04-16

363

Integrin ?PS3/??-mediated phagocytosis of apoptotic cells and bacteria in Drosophila.  

PubMed

Integrins exert a variety of cellular functions as heterodimers of two transmembrane subunits named ? and ?. Integrin ??, a ?-subunit of Drosophila integrin, is involved in the phagocytosis of apoptotic cells and bacteria. Here, we searched for an ?-subunit that forms a complex and cooperates with ??. Examinations of RNAi-treated animals suggested that ?PS3, but not any of four other ?-subunits, is required for the effective phagocytosis of apoptotic cells in Drosophila embryos. The mutation of ?PS3-encoding scb, deficiency, insertion of P-element, or alteration of nucleotide sequences, brought about a reduction in the level of phagocytosis. The defect in phagocytosis by deficiency was reverted by the forced expression of scb. Furthermore, flies in which the expression of both ?PS3 and ?? was inhibited by RNAi showed a level of phagocytosis almost equal to that observed in flies with RNAi for either subunit alone. A loss of ?PS3 also decreased the activity of larval hemocytes in the phagocytosis of Staphylococcus aureus. Finally, a co-immunoprecipitation analysis using a Drosophila cell line treated with a chemical cross-linker suggested a physical association between ?PS3 and ??. These results collectively indicated that integrin ?PS3/?? serves as a receptor in the phagocytosis of apoptotic cells and bacteria by Drosophila phagocytes. PMID:23426364

Nonaka, Saori; Nagaosa, Kaz; Mori, Toshinobu; Shiratsuchi, Akiko; Nakanishi, Yoshinobu

2013-02-20

364

Generation of clinically relevant "induced pluripotent stem" (iPS) cells.  

PubMed

Proviral expression of early development genes Oct4 and Sox2, in concert with cMyc and Klf4 or Nanog and Lin28, can induce differentiated cells to adopt morphological and functional characteristics of pluripotency indistinguishable from embryonic stem cells. Termed induced pluripotent stem (iPS) cells, in mice the pluripotency of these cells was confirmed by altered gene/surface antigen expression, remodeling of the epigenome, ability to contribute to embryonic lineages following blastocyst injection and commitment to all three germ layers in teratomas and liveborn chimeras. Importantly, in vitro directed differentiation of iPS cells yield cells capable of treating mouse models of humanized disease. Despite these impressive results, iPS cell conversion is frustratingly inefficient. Also, the unpredictable and random mutagenesis imposed on the host cell genome, inherent with integrative viral methodologies, continues to hamper use of these cells in a therapeutic setting. This has initiated exploration of non-integrating strategies for generating iPS cells. Here, we review mechanisms that drive conversion of somatic cells to iPS cells and the strategies adopted to circumvent integrative viral strategies. Finally, we discuss practical, ethical and legal considerations that require addressing before iPS cells can realize their potential as patient-specific cells for treatment of degenerative disease. PMID:23264997

Heffernan, Corey; Sumer, Huseyin; Verma, Paul J

2011-01-01

365

Efficient Generation of Virus-Free iPS Cells Using Liposomal Magnetofection  

PubMed Central

The generation of induced pluripotent stem (iPS) cells is a powerful tool in regenerative medicine, and advances in nanotechnology clearly have great potential to enhance stem cell research. Here, we introduce a liposomal magnetofection (LMF) method for iPS cell generation. Efficient conditions for generating virus-free iPS cells from mouse embryonic fibroblast (MEF) cells were determined through the use of different concentrations of CombiMag nanoparticle-DNA(pCX-OKS-2A and pCX-cMyc)-lipoplexes and either one or two cycles of the LMF procedure. The cells were prepared in a short reprogramming time period (?8 days, 0.032–0.040%). Among the seven LMF-iPS cell lines examined, two were confirmed to be integration-free, and an integration-free LMF-iPS cell line was produced under the least toxic conditions (single LMF cycle with a half-dose of plasmid). This cell line also displayed in vitro/in vivo pluripotency, including teratoma formation and chimeric mouse production. In addition, the safety of CombiMag-DNA lipoplexes for the transfection of MEF cells was confirmed through lactate dehydrogenase activity assay and transmission electron microscopy. These results demonstrated that the LMF method is simple, effective, and safe. LMF may represent a superior technique for the generation of virus-free or integration-free iPS cell lines that could lead to enhanced stem cell therapy in the future.

Park, Hyo Young; Noh, Eun Hyung; Chung, Hyung-Min; Kang, Man-Jong; Kim, Eun Young; Park, Se Pill

2012-01-01

366

iPS Cell Intervention Rescues Wall Motion Disparity Achieving Biological Cardiac Resynchronization Post-Infarction.  

PubMed

Dyssynchronous myocardial motion aggravates cardiac pump function. Cardiac resynchronization using pacing devices is a standard-of-care in the management of heart failure. Post-infarction, however, scar tissue formation impedes the efficacy of device-based therapy. The present study tests a regenerative approach aimed at targeting the origin of abnormal motion to prevent dyssynchronous organ failure. Induced pluripotent stem (iPS) cells harbor a reparative potential, and were here bioengineered from somatic fibroblasts reprogrammed with the stemness factors OCT3/4, SOX2, KLF4, and c-MYC. In a murine infarction model, within 30-min after coronary ligation, iPS cells were delivered to mapped infarcted areas. Focal deformation and dysfunction underlying progressive heart failure was resolved prospectively using speckle-tracking imaging. Tracked at high temporal and spatial resolution, regional iPS cell transplantation restored, within 10 days post-infarction, the contractility of targeted infarcted foci and nullified conduction delay in adjacent non-infarcted regions. Local iPS cell therapy, but not delivery of parental fibroblasts or vehicle, prevented or normalized abnormal strain patterns correcting the decrease in peak strain, disparity of time-to-peak strain, and pathological systolic stretch. Focal benefit of iPS cell intervention translated into improved left ventricular conduction and contractility, reduced scar, and reversal of structural remodeling, protecting from organ decompensation. Thus, in ischemic cardiomyopathy targeted iPS cell transplantation synchronized failing ventricles, offering a regenerative strategy to achieve biological resynchronization. PMID:23568891

Yamada, Satsuki; Nelson, Timothy; Kane, Garvan; Martinez-Fernandez, Almudena; Crespo-Diaz, Ruben J; Ikeda, Yasuhiro; Terzic, Carmen; Terzic, Andre

2013-05-13

367

Light-induced short-term adaptation mechanisms under redox control in the PS II-LHCII supercomplex: LHC II state transitions and PS II repair cycle  

NASA Astrophysics Data System (ADS)

Oxygenic photosynthesis takes place in the thylakoid membranes of cyanobacteria, algae and higher plants. While cyanobacteria have adapted to relatively constant environments, higher plants had to evolve mechanisms to adapt to continuous environmental changes. These include changes in light intensity, temperature and availability of water. One of the great challenges in plant cell biology is therefore to determine the regulatory mechanisms employed by higher plants and some algae to adapt to these constant environmental changes. The particular emphasis of this review is the description and characterisation of light-induced redox-controlled processes regulating the photosynthetic reactions, which involves maintaining maximal electron transport flow through the PS II-Cytb6f-PS I-FoF1ATPase electron transport chain and minimising light-induced oxidative damage to PS II which drives the highly oxidising water-splitting reaction. Two of the mechanisms involved in such short-term regulation processes are known as light harvesting complex II (LHC II) state transitions and photosystem II (PS II) repair cycle. They are followed by, and indeed may be a precondition in order to establish, the onset of the subsequent long-term mechanisms of regulation. In particular, the redox control of LHC II state transitions by reversible phosphorylation has been in the focus of many investigations, leading to many new results demonstrating the complexity of thylakoid-associated redox control mechanisms.

Kruse, Olaf

2001-05-01

368

A Myb transcription factor of Phytophthora sojae, regulated by MAP kinase PsSAK1, is required for zoospore development.  

PubMed

PsSAK1, a mitogen-activated protein (MAP) kinase from Phytophthora sojae, plays an important role in host infection and zoospore viability. However, the downstream mechanism of PsSAK1 remains unclear. In this study, the 3'-tag digital gene expression (DGE) profiling method was applied to sequence the global transcriptional sequence of PsSAK1-silenced mutants during the cysts stage and 1.5 h after inoculation onto susceptible soybean leaf tissues. Compared with the gene expression levels of the recipient P. sojae strain, several candidates of Myb family were differentially expressed (up or down) in response to the loss of PsSAK1, including of a R2R3-type Myb transcription factor, PsMYB1. qRT-PCR indicated that the transcriptional level of PsMYB1 decreased due to PsSAK1 silencing. The transcriptional level of PsMYB1 increased during sporulating hyphae, in germinated cysts, and early infection. Silencing of PsMYB1 results in three phenotypes: a) no cleavage of the cytoplasm into uninucleate zoospores or release of normal zoospores, b) direct germination of sporangia, and c) afunction in zoospore-mediated plant infection. Our data indicate that the PsMYB1 transcription factor functions downstream of MAP kinase PsSAK1 and is required for zoospore development of P. sojae. PMID:22768262

Zhang, Meng; Lu, Jing; Tao, Kai; Ye, Wenwu; Li, Aining; Liu, Xiaoyun; Kong, Liang; Dong, Suomeng; Zheng, Xiaobo; Wang, Yuanchao

2012-06-29

369

Therapeutic effect of human iPS-cell-derived myeloid cells expressing IFN-? against peritoneally disseminated cancer in xenograft models.  

PubMed

We recently developed a method to generate myeloid cells with proliferation capacity from human iPS cells. iPS-ML (iPS-cell-derived myeloid/macrophage line), generated by introducing proliferation and anti-senescence factors into iPS-cell-derived myeloid cells, grew continuously in an M-CSF-dependent manner. A large number of cells exhibiting macrophage-like properties can be readily obtained by using this technology. In the current study, we evaluated the possible application of iPS-ML in anti-cancer therapy. We established a model of peritoneally disseminated gastric cancer by intraperitoneally injecting NUGC-4 human gastric cancer cells into SCID mice. When iPS-ML were injected intraperitoneally into the mice with pre-established peritoneal NUGC-4 tumors, iPS-ML massively accumulated and infiltrated into the tumor tissues. iPS-ML expressing IFN-? (iPS-ML/IFN-?) significantly inhibited the intra-peritoneal growth of NUGC-4 cancer. Furthermore, iPS-ML/IFN-? also inhibited the growth of human pancreatic cancer MIAPaCa-2 in a similar model. iPS-ML are therefore a promising treatment agent for peritoneally disseminated cancers, for which no standard treatment is currently available. PMID:23826321

Koba, Chihiro; Haruta, Miwa; Matsunaga, Yusuke; Matsumura, Keiko; Haga, Eriko; Sasaki, Yuko; Ikeda, Tokunori; Takamatsu, Koutaro; Nishimura, Yasuharu; Senju, Satoru

2013-06-24

370

PS-341 and Histone Deacetylase Inhibitor Synergistically Induce Apoptosis in Head and Neck Squamous Cell Carcinoma Cells  

PubMed Central

Proteasome inhibitor PS-341 (also known as Bortezomib) and histone deacetylase (HDAC) inhibitors have emerged as novel therapeutic agents for a variety of malignancies. In this study, we examined whether PS-341 and the HDAC inhibitor trichostatin A (TSA) induced apoptosis in head and neck squamous cell carcinoma (HNSCC), a common and lethal malignancy. We found that, while TSA treatment alone did not induce apoptosis in HNSCC cells, it significantly enhanced PS-341-induced apoptosis in HNSCC cells in vitro. Consistently, TSA significantly improved PS-341-mediated inhibition of HNSCC tumor growth in nude mice. Mechanistically, we found that TSA increased PS-341-induced Noxa expression and caspase activation in HNSCC cells. The knock-down of Noxa significantly reduced apoptosis induced by co-treatment of PS-341 and TSA. Taken together, our results provide new insight into the mechanisms of synergistic antitumor activity of PS-341 and HDAC inhibitor regimen, offering a new therapeutic strategy for HNSCC patients.

Kim, JinKoo; Guan, Jean; Chang, Insoon; Chen, Xiaohong; Han, Demin; Wang, Cun-Yu

2010-01-01

371

Validity and Reliability of the Dutch Adaptation of the Psoriatic Arthritis Quality of Life (PsAQoL) Questionnaire  

PubMed Central

Objective The Psoriatic Arthritis Quality of Life (PsAQoL) questionnaire is a disease- specific instrument developed to measure quality of life (QoL) in patients with psoriatic arthritis (PsA). The aim of this study was to translate the measure into Dutch and to determine its psychometric properties. Method Translation of the original English PsAQoL into Dutch was performed by bilingual and lay panel. Ten field-test interviews with PsA patients were performed to assess face and content validity. In total, 211 PsA patients were included in a test-retest postal survey to investigate the reliability and construct validity of the Dutch adaptation of the PsAQoL. The PsAQoL, Health Assessment Questionnaire (HAQ) and Skindex-17 were administered on two different occasions approximately two weeks apart. Results The Dutch version of the PsAQoL was found to be relevant, understandable and easy to complete in only a few minutes. It correlated as expected with the HAQ (Spearman’s ??=?0.72) and the 2 subscales of the Skindex-17 (??=?0.40 for the psychosocial and ??=?0.46 for the symptom scale). Furthermore, the measure had good internal consistency (Cronbach’s ??=?0.92) and test-retest reliability (??=?0.89). The PsAQoL was able to define groups of patients based on self-reported general health status, self-reported severity of PsA and flare of arthritis. Duration of PsA did not influence PsAQoL scores. Conclusions The Dutch version of the PsAQoL is a valid and reliable questionnaire suitable for use in clinical or research settings to asses PsA-specific QoL.

McKenna, Stephen P.; Houtman, Pieternella M.; Brouwer, Elisabeth; Spoorenberg, Anneke

2013-01-01

372

Alkaline serine protease produced from citric acid by Bacillus alcalophilus subsp. halodurans KP 1239.  

PubMed

Maximum production of alkaline serine protease by Bacillus alcalophilus subsp. halodurans KP 1239 was achieved after 24 h cultivation, at an initial pH of 7.6, on a medium containing 1.0% sodium citrate, 0.3% yeast extract, and 0.3% KH2PO4. The enzyme was purified to crystalline form from culture broth. The enzyme was most active at 60 degrees C and at pH 11.5. The molecular weight, isoelectric point and sedimentation coefficient in water at 20 degrees C were estimated as 29,000, 8.8 and 3.3S, respectively. The N-terminal amino acid sequence was Ala-Gln-Ser-Val-Pro-Trp-Gly-Ile-Ser-Arg-Val-Gln-Ala-Pro-Ala-Ala- His-Asn-Arg-Gly-. The enzyme shared its antigenic determinants with B. alcalophilus ATCC 21522 serine protease, but not with the subtilisins Carlsberg and BPN'. PMID:1370021

Takii, Y; Kuriyama, N; Suzuki, Y

1990-10-01

373

On the modeling of snake venom serine proteinase interactions with benzamidine-based thrombin inhibitors  

PubMed Central

Pit viper venoms contain a number of serine proteinases that exhibit one or more thrombin-like activities on fibrinogen and platelets, this being the case for the kinin-releasing and fibrinogen-clotting KN-BJ from the venom of Bothrops jararaca. A three-dimensional structural model of the KN-BJ2 serine proteinase was built by homology modeling using the snake venom plasminogen activator TSV-PA as a major template and porcine kallikrein as additional structural support. A set of intrinsic buried waters was included in the model and its behavior under dynamic conditions was molecular dynamics simulated, revealing a most interesting similarity pattern to kallikrein. The benzamidine-based thrombin inhibitors ?-NAPAP, 3-TAPAP, and 4-TAPAP were docked into the refined model, allowing for a more insightful functional characterization of the enzyme and a better understanding of the reported comparatively low affinity of KN-BJ2 toward those inhibitors.

Henriques, Elsa S.; Fonseca, Nelson; Ramos, Maria Joao

2004-01-01

374

Inhibition of protein kinases by balanol: specificity within the serine/threonine protein kinase subfamily.  

PubMed

Balanol is a potent inhibitor of cyclic AMP-dependent protein kinase and protein kinase C, acting competitively with ATP with an affinity 3000 times that of ATP. We tested the capacity of balanol to inhibit representative serine- and threonine-specific protein kinases from the protein kinase subfamily that shares a common conserved catalytic core with cyclic AMP-dependent protein kinase. Balanol's pattern of interactions indicates considerable diversity of the ATP/balanol-binding sites of protein kinases within familial groups and even among isoforms of the same kinase. We propose that balanol is a protean structure that may be modified to produce selective, high-affinity inhibitors and probes of the ATP-binding sites of serine/threonine protein kinases. PMID:10419556

Setyawan, J; Koide, K; Diller, T C; Bunnage, M E; Taylor, S S; Nicolaou, K C; Brunton, L L

1999-08-01

375

The Effects of Midgut Serine Proteases on Dengue Virus Type 2 Infectivity of Aedes aegypti  

PubMed Central

Dengue viruses (DENV) cause significant morbidity and mortality worldwide and are transmitted by the mosquito Aedes aegypti. Mosquitoes become infected after ingesting a viremic bloodmeal, and molecular mechanisms involved in bloodmeal digestion may affect the ability of DENV to infect the midgut. We used RNA interference (RNAi) to silence expression of four midgut serine proteases and assessed the effect of each RNAi phenotype on DENV-2 infectivity of Aedes aegypti. Silencing resulted in significant reductions in protease mRNA levels and correlated with a reduction in activity except in the case of late trypsin. RNA silencing of chymotrypsin, early and late trypsin had no effect on DENV-2 infectivity. However, silencing of 5G1 or the addition of soybean trypsin inhibitor to the infectious bloodmeals significantly increased midgut infection rates. These results suggest that some midgut serine proteases may actually limit DENV-2 infectivity of Ae. aegypti.

Brackney, Doug E.; Foy, Brian D.; Olson, Ken E.

2009-01-01

376

Haploinsufficiency of cytosolic serine hydroxymethyltransferase in the Smith-Magenis syndrome.  

PubMed Central

Folate-dependent one-carbon metabolism is critical for the synthesis of numerous cellular constituents required for cell growth, and serine hydroxymethyltransferase (SHMT) is central to this process. Our studies reveal that the gene for cytosolic SHMT (cSHMT) maps to the critical interval for Smith-Magenis syndrome (SMS) on chromosome 17p11.2. The basic organization of the cSHMT locus on chromosome 17 was determined and was found to be deleted in all 26 SMS patients examined by PCR, FISH, and/or Southern analysis. Furthermore, with respect to haploinsufficiency, cSHMT enzyme activity in patient lymphoblasts was determined to be approximately 50% that of unaffected parent lymphoblasts. Serine, glycine, and folate levels were also assessed in three SMS patients and were found to be within normal ranges. The possible effects of cSHMT hemizygosity on the SMS phenotype are discussed. Images Figure 1 Figure 2 Figure 3

Elsea, S H; Juyal, R C; Jiralerspong, S; Finucane, B M; Pandolfo, M; Greenberg, F; Baldini, A; Stover, P; Patel, P I

1995-01-01

377

QSAR and docking studies of HCV NS3 serine protease inhibitors.  

PubMed

Hepatitis C virus (HCV) is a Hepacivirus that causes chronic liver disease, leading to hepatocellular carcinoma, cirrhosis, and chronic hepatitis in about 3% of the world population. In this study, novel HCV NS3 serine protease inhibitors based on 93 boceprevir analogs were studied by QSAR analyses using thermodynamic, structural and topological descriptors, including E-state descriptors. Novel compounds were proposed using the QSAR models. Both models were highly predictive, with calibration, leave-one-out validation and external validation R2 of 0.66, 0.65 and 0.52, respectively. The most promising structures were docked into the HCV NS3 serine protease active site demonstrating, then, the high affinity of some new structures. PMID:23140577

da Cunha, Elaine F F; Matos, Karina S; Ramalho, Teodorico C

2013-09-01

378

Function and regulation of serine/threonine phosphatases in the healthy and diseased heart.  

PubMed

Protein phosphorylation is a major control mechanism of a wide range of physiological processes and plays an important role in cardiac pathophysiology. Serine/threonine protein phosphatases control the dephosphorylation of a variety of cardiac proteins, thereby fine-tuning cardiac electrophysiology and function. Specificity of protein phosphatases type-1 and type-2A is achieved by multiprotein complexes that target the catalytic subunits to specific subcellular domains. Here, we describe the composition, regulation and target substrates of serine/threonine phosphatases in the heart. In addition, we provide an overview of pharmacological tools and genetic models to study the role of cardiac phosphatases. Finally, we review the role of protein phosphatases in the diseased heart, particularly in ventricular arrhythmias and atrial fibrillation and discuss their role as potential therapeutic targets. PMID:24051368

Heijman, Jordi; Dewenter, Matthias; El-Armouche, Ali; Dobrev, Dobromir

2013-09-16

379

Eukaryotic phytochromes: Light-regulated serine/threonine protein kinases with histidine kinase ancestry  

PubMed Central

The discovery of cyanobacterial phytochrome histidine kinases, together with the evidence that phytochromes from higher plants display protein kinase activity, bind ATP analogs, and possess C-terminal domains similar to bacterial histidine kinases, has fueled the controversial hypothesis that the eukaryotic phytochrome family of photoreceptors are light-regulated enzymes. Here we demonstrate that purified recombinant phytochromes from a higher plant and a green alga exhibit serine/threonine kinase activity similar to that of phytochrome isolated from dark grown seedlings. Phosphorylation of recombinant oat phytochrome is a light- and chromophore-regulated intramolecular process. Based on comparative protein sequence alignments and biochemical cross-talk experiments with the response regulator substrate of the cyanobacterial phytochrome Cph1, we propose that eukaryotic phytochromes are histidine kinase paralogs with serine/threonine specificity whose enzymatic activity diverged from that of a prokaryotic ancestor after duplication of the transmitter module.

Yeh, Kuo-Chen; Lagarias, J. Clark

1998-01-01

380

Enhancement of cyanogen bromide cleavage yields for methionyl-serine and methionyl-threonine peptide bonds.  

PubMed

Cyanogen bromide (CNBr) is a common chemical used to hydrolyze peptide bonds C-terminal to methionine residues in peptides and proteins. In most cases, the efficiency of this bond cleavage is greater than 90% except in situations where a serine or threonine residue follows methionine in the amino acid sequence. We have explored the mechanism of the methionyl-serine and methionyl-threonine CNBr cleavage inefficiencies and have developed a simple methodology to more than double cleavage yields relative to standard literature conditions. This method entails increasing the concentration of water during the cleavage reaction either by reducing the formic acid concentration or by performing the cleavage in an acidic aqueous medium. This approach provides a more desirable methodology from the perspective of enhanced yields and greater ease of handling in cases of large-scale use. PMID:9887207

Kaiser, R; Metzka, L

1999-01-01

381

Bioinformatic search of plant microtubule-and cell cycle related serine-threonine protein kinases  

Microsoft Academic Search

A bioinformatic search was carried for plant homologues of human serine-threonine protein kinases involved in regulation of cell division and microtubule protein phosphorylation (SLK, PAK6, PAK7, MARK1, MAST2, TTBK1, TTBK2, AURKA, PLK1, PLK4 and PASK). A number of SLK, MAST2 and AURKA plant homologues were identified. The closest identified homologue of human AURKA kinase was a protein of unknown function,

Pavel A Karpov; Elena S Nadezhdina; Alla I Yemets; Vadym G Matusov; Alexey Yu Nyporko; Nadezhda Yu Shashina; Yaroslav B Blume

2010-01-01

382

The Catalytic Role of the Active Site Aspartic Acid in Serine Proteases  

Microsoft Academic Search

The role of the aspartic acid residue in the serine protease catalytic triad Asp, His, and Ser has been tested by replacing Asp102 of trypsin with Asn by site-directed mutagenesis. The naturally occurring and mutant enzymes were produced in a heterologous expression system, purified to homogeneity, and characterized. At neutral pH the mutant enzyme activity with an ester substrate and

Charles S. Craik; Steven Roczniak; Corey Largman; William J. Rutter

1987-01-01

383

The phosphorylation of caveolin-2 on serines 23 and 36 modulates caveolin-1-dependent caveolae formation  

Microsoft Academic Search

Caveolin-1 and -2 are the two major coat proteins found in plasma membrane caveolae of most of cell types. Here, by using adenoviral transduction of either caveolin-1 or caveolin-2 or both isoforms into cells lacking both caveolins, we demonstrate that caveolin-2 positively regulates caveolin-1-dependent caveolae formation. More importantly, we show that caveolin-2 is phosphorylated in vivo at two serine residues

Grzegorz Sowa; Marc Pypaert; David Fulton; William C. Sessa

2003-01-01

384

Effects of Enterococcus faecalis fsr Genes on Production of Gelatinase and a Serine Protease and Virulence  

Microsoft Academic Search

Three agr-like genes (fsrA, fsrB, and fsrC, for Enterococcus faecalis regulator) were found upstream of the previously reported gelatinase gene (gelE) and a downstream putative serine protease gene (sprE; accession number Z12296) of Enterococcus faecalis OG1RF. The deduced amino acid sequence of fsrA shows 26% identity and 38% similarity to Staphylococcus aureus AgrA (the response regulator of the accessory gene

XIANG QIN; KAVINDRA V. SINGH; GEORGE M. WEINSTOCK; BARBARA E. MURRAY

2000-01-01

385

Akt Phosphorylation of Serine 21 on Pak1 Modulates Nck Binding and Cell Migration  

Microsoft Academic Search

The p21-activated protein kinases (Paks) regulate cellular proliferation, differentiation, transformation, and survival through multiple downstream signals. Paks are activated directly by the small GTPases Rac and Cdc42 and several protein kinases including Akt and PDK-1. We found that Akt phosphorylated and modestly activated Pak1 in vitro. The major site phosphorylated by Akt on Pak1 mapped to serine 21, a site

Guo-Lei Zhou; Ya Zhuo; Charles C. King; Benjamin H. Fryer; Gary M. Bokoch; Jeffrey Field

2003-01-01

386

Crystal structure of the high-alkaline serine protease PB92 from Bacillus alcalophilus  

Microsoft Academic Search

The crystal structure of a serine protease from the alkalophilic strain Bacillus alcalophilus PB92 has been determined by X-ray diffraction at 1.75 Å resolution. The structure has been solved by molecular replacement using the atomic model of subtilisin Carlsberg. The model of the PB92 protease has been refined to an R-factor of 14.0% and contains 1882 protein atoms, two calcium

B. W. Dijkstra; L. J. S. M. Mulleners; O. Misset; K. H. Kalk; H. Kelders; A. V. Teplyakov; J. M. van der Laan

1992-01-01

387

Alkaline serine protease produced from citric acid by Bacillus alcalophilus subsp. halodurans KP 1239  

Microsoft Academic Search

Maximum production of alkaline serine protease by Bacillus alcalophilus subsp. halodurans KP 1239 was achieved after 24 h cultivation, at an initial pH of 7.6, on a medium containing 1.0% sodium citrate, 0.3% yeast extract, and 0.3% KH2PO4. The enzyme was purified to crystalline form from culture broth. The enzyme was most active at 60° C and at pH 11.5.

Yukio Takii; Naohiro Kuriyama; Yuzuru Suzuki

1990-01-01

388

Nucleocytoplasmic shuttling of the HSV2 serine\\/threonine kinase Us3  

Microsoft Academic Search

The alphaherpesvirus serine\\/threonine kinase Us3 plays diverse roles in virus multiplication and modifies both nuclear and cytoplasmic substrates. We recently reported that treatment of HSV-2 Us3-transfected and HSV-2-infected cells with leptomycin B, an inhibitor of nuclear export mediated by interaction of chromosomal regional maintenance protein (CRM1) with leucine rich nuclear export signals (NESs), resulted in nuclear trapping of Us3. Here,

Renée L. Finnen; Susan M. Johnston; Casey E. Neron; Bruce W. Banfield

2011-01-01

389

Serine 68 Phospholemman Phosphorylation during Forskolin-Induced Swine Carotid Artery Relaxation  

Microsoft Academic Search

Background: Phospholemman (PLM) is an abundant phosphoprotein in the plasma membrane of cardiac, skeletal and smooth muscle. It is a member of the FXYD family of proteins that bind to and regulate the Na,K-ATPase. Protein kinase A (PKA) is known to phosphorylate PLM on serine 68 (S68), although the functional effect of S68 PLM phosphorylation is unclear. We therefore evaluated

Christopher M. Rembold; Marcia L. Ripley; Melissa K. Meeks; Lisa M. Geddis; Howard C. Kutchai; Francesca M. Marassi; Joseph Y. Cheung; J. Randall Moorman

2005-01-01

390

Gene organization of a Plasmodium falciparum serine hydroxymethyltransferase and its functional expression in Escherichia coli  

Microsoft Academic Search

The global emergence of drug-resistant malarial parasites necessitates identification and characterization of novel drug targets. Three reactions are involved in methylenetetrahydrofolate recycling: Thymidylate synthase (TS), dihydrofolate reductase (DHFR), and serine hydroxymethyltransferase (SHMT). Malarial bifunctional DHFR-TS is a well-studied, important target of established drugs such as pyrimethamine and cycloguanil. In sharp contrast, malarial SHMT remains largely uncharacterized. In the present study,

Suad Alfadhli; Pradipsinh K Rathod

2000-01-01

391

Serine Threonine Receptor-Associated Protein (STRAP) plays a role in the maintenance of mesenchymal morphology  

Microsoft Academic Search

The stromal tissue, made of extracellular matrix and mesenchymal cells, is vital for the functional design of all complex tissues. Fibroblasts are key components of stromal tissue and play a crucial role during organ development, wound repair, angiogenesis and fibrosis. We have previously reported the identification of a novel WD-domain protein, STRAP11STRAP: Serine Threonine Receptor-Associated Protein, TGF-?: transforming growth factor-?,

Nilesh D. Kashikar; Jennifer Reiner; Arunima Datta; Pran K. Datta

2010-01-01

392

Identification and Characterization of SSTK, a Serine\\/Threonine Protein Kinase Essential for Male Fertility  

Microsoft Academic Search

Here we describe and characterize a small serine\\/threonine kinase (SSTK) which consists solely of the N- and C-lobes of a protein kinase catalytic domain. SSTK protein is highly conserved among mammals, and no close homologues were found in the genomes of nonmammalian organisms. SSTK specifically interacts with HSP90-1, HSC70, and HSP70 proteins, and this association appears to be required for

Nikolay A. Spiridonov; Lily Wong; Patricia M. Zerfas; Matthew F. Starost; Svetlana D. Pack; Cloud P. Paweletz; Gibbes R. Johnson

2005-01-01

393

Activation of pro-caspase-7 by serine proteases includes a non-canonical specificity.  

PubMed Central

As a model to investigate the mechanism of caspase activation we have analysed the processing of pro-caspase-7 by serine proteases with varied specificities. The caspase-7 zymogen was rapidly activated by granzyme B and more slowly by subtilisin and cathepsin G, generating active enzymes with similar kinetic properties. Significantly, cathepsin G activated the zymogen by cleaving at a Gln-Ala bond, indicating that the canonical cleavage specificity at aspartic acid is not required for activation.

Zhou, Q; Salvesen, G S

1997-01-01

394

Endogenous Serine Protease Inhibitor Modulates Epileptic Activity and Hippocampal Long-Term Potentiation  

Microsoft Academic Search

Protease nexin-1 (PN-1), a member of the serpin superfamily, controls the activity of extracellular serine proteases and is expressed in the brain. Mutant mice overexpressing PN-1 in brain under the control of the Thy-1 promoter (Thy 1\\/PN-1) or lacking PN-1 (PN-12\\/2) were found to develop epileptic activ- ity in vivo and in vitro. Theta burst-induced long-term potenti- ation (LTP) and

Andreas Luthi; Herman van der Putten; Florence M. Botteri; Isabelle M. Mansuy; Marita Meins; Uwe Frey; Gilles Sansig; Chantal Portet; Markus Schmutz; Markus Schroder; Cordula Nitsch; Jean-Paul Laurent; Denis Monard

1997-01-01

395

Modulation of the exocellular serine-thiol proteinase activity of Paracoccidioides brasiliensis by neutral polysaccharides  

Microsoft Academic Search

Our group characterized an exocellular serine-thiol proteinase activity in the yeast phase of Paracoccidioides brasiliensis (PbST), a dimorphic human pathogen. The fungal proteinase is able to cleave in vitro, at pH 7.4, proteins associated with the basal membrane, such as human laminin and fibronectin, type IV collagen and proteoglycans. In the present study, we investigated the influence of glycosaminoglycans (GAGs)

Alisson L. Matsuo; Ivarne I. L. Tersariol; Silvia I. Kobata; Luiz R. Travassos; Adriana K. Carmona; Rosana Puccia

2006-01-01

396

Regulation of VASP serine 157 phosphorylation in human neutrophils after stimulation by a chemoattractant  

Microsoft Academic Search

Vasodilator-stimulated phosphoprotein (VASP) is a cAMP-dependent protein kinase A (PKA) substrate, which links cellular signaling to cytoskeletal organization and cellular movement. VASP is phosphorylated by PKA on serine 157 (Ser 157), which is required for VASP function in platelet adhesion and fibroblast motility. Our hy- pothesis is that PKA regulates neutrophil migration through VASP Ser 157 phosphorylation. The ob- jective

Rachael E. Eckert; Samuel L. Jones

2007-01-01

397

Matriptase-3 is a novel phylogenetically preserved membrane-anchored serine protease with broad serpin reactivity.  

PubMed

We report in the present study the bioinformatic identification, molecular cloning and biological characterization of matriptase-3, a novel membrane-anchored serine protease that is phylogenetically preserved in fish, birds, rodents, canines and primates. The gene encoding matriptase-3 is located on syntenic regions of human chromosome 3q13.2, mouse chromosome 16B5, rat chromosome 11q21 and chicken chromosome 1. Bioinformatic analysis combined with cDNA cloning predicts a functional TTSP (type II transmembrane serine protease) with 31% amino acid identity with both matriptase/MT-SP1 and matriptase-2. This novel protease is composed of a short N-terminal cytoplasmic region followed by a transmembrane domain, a stem region with one SEA, two CUB and three LDLRa (low-density lipoprotein receptor domain class A) domains and a C-terminal catalytic serine protease domain. Transcript analysis revealed restricted, species-conserved expression of matriptase-3, with the highest mRNA levels in brain, skin, reproductive and oropharyngeal tissues. The full-length matriptase-3 cDNA directed the expression of a 90 kDa N-glycosylated protein that localized to the cell surface, as assessed by cell-surface biotin labelling. The purified activated matriptase-3 serine protease domain expressed in insect cells hydrolysed synthetic peptide substrates, with a strong preference for Arg at position P(1), and showed proteolytic activity towards several macromolecular substrates, including gelatin, casein and albumin. Interestingly, activated matriptase-3 formed stable inhibitor complexes with an array of serpins, including plasminogen activator inhibitor-1, protein C inhibitor, alpha1-proteinase inhibitor, alpha2-antiplasmin and antithrombin III. Our study identifies matriptase-3 as a novel biologically active TTSP of the matriptase subfamily having a unique expression pattern and post-translational regulation. PMID:15853774

Szabo, Roman; Netzel-Arnett, Sarah; Hobson, John P; Antalis, Toni M; Bugge, Thomas H

2005-08-15

398

Biosynthesis and properties of an extracellular thermostable serine alkaline protease from Virgibacillus pantothenticus  

Microsoft Academic Search

In this communication, we report the presence of a newly identified serine alkaline protease producing bacteria, Virgibacillus pantothenticus (MTCC 6729) in the fresh chicken meat samples and the factors affecting biosynthesis as well as characterization of protease.\\u000a The strain produced only 14.3 U ml?1 protease in the standard medium after 72 h of incubation, while in optimized culture conditions the production of protease

Amit Gupta; Babu Joseph; Abin Mani; George Thomas

2008-01-01

399

Serine racemase homologue of Saccharomyces cerevisiae has L- threo-3-hydroxyaspartate dehydratase activity  

Microsoft Academic Search

The NH2-terminal amino acid sequence of L-threo-3-hydroxyaspartate dehydratase from Pseudomonas sp. T62 showed significant similarity to that of the SRY1 gene product of Saccharomyces cerevisiae (serine racemase in yeast). SRY1 was cloned and expressed in Escherichia coli, and the gene product was purified and partially characterized. The SRY1 gene product exhibited dehydratase activity specific for L-threo-3-hydroxyaspartate (Km=3.9 mM, Vmax=110 ?mol

Masaru Wada; Shigeru Nakamori; Hiroshi Takagi

2003-01-01

400

Engineering of the Lactococcus lactis serine proteinase by construction of hybrid enzymes  

Microsoft Academic Search

Plasmids containing wild-type and hybrid proteinase genes were constructed from DNA fragments of the prtP genes of Lactococcus lactis strains Wg2 and SK11. These plasmids were introduced into the plasmid-free strain L. lactis MG1363. The serine proteinases produced by these L. lactis strains were isolated, and their cleavage specificity and rate towards ?s1-and ?-casein was investigated. The catalytic properties of

Pieter Vos; Ingrid J. Boerrigter; Girbe Buist; Alfred J. Haandrikman; Monique Nijhuis; Marjon B. de Reuver; Roland J. Siezen; Gerard Venema; Willem M. de Vos; Jan Kok

1991-01-01

401

The serine\\/threonine kinase cyclin G-associated kinase regulates epidermal growth factor receptor signaling  

Microsoft Academic Search

Cyclin G-associated kinase (GAK) is a serine\\/threonine kinase that features high homology outside its kinase domain with auxilin. Like auxilin, GAK has been shown to be a cofactor for uncoating clathrin vesicles in vitro. We investigated epidermal growth factor (EGF) receptor-mediated signaling in cells, in which GAK is down-regulated by small hairpin RNAs. Here, we report that down-regulation of GAK

Lei Zhang; Ole Gjoerup; Thomas M. Roberts

2004-01-01

402

Expression and Characterization of the Mycobacterium tuberculosis Serine\\/Threonine Protein Kinase PknB  

Microsoft Academic Search

PknB is a member of the newly discovered eukaryotic-like protein serine\\/threonine kinase (PSTK) family of proteins. The pknB gene was cloned and expressed in Escherichia coli. The active recombinant protein was purified and shown to be reactive with antiphosphoserine antibodies, as well as with antibodies to the phosphorylated eukaryotic Ser\\/Thr kinases mitogen-activated protein kinase kinase 3 and 6, P38, and

YOSSEF AV-GAY; SARWAT JAMIL; STEVEN J. DREWS

1999-01-01

403

Characterization of Plasmodium falciparum serine hydroxymethyltransferase—A potential antimalarial target  

Microsoft Academic Search

Serine hydroxymethyltransferase (SHMT) is a ubiquitous enzyme required for folate recycling and dTMP synthesis. A cDNA encoding Plasmodium falciparum (Pf) SHMT was expressed as a hexa-histidine tagged protein in Escherichia coli BL21-CodonPlus® (DE3)-RIL. The protein was purified and the process yielded 3.6mg protein\\/l cell culture. Recombinant His6-tagged PfSHMT exhibits a visible spectrum characteristic of pyridoxal-5?-phosphate enzyme and catalyzes the reversible

Somchart Maenpuen; Kittipat Sopitthummakhun; Yongyuth Yuthavong; Pimchai Chaiyen; Ubolsree Leartsakulpanich

2009-01-01

404

A Novel Transmembrane Serine Protease (TMPRSS3) Overexpressed in Pancreatic Cancer1,2  

Microsoft Academic Search

We report the characterization of a novel serine protease of the chy- motrypsin family, recently isolated by cDNA-representational difference analysis, as a gene overexpressed in pancreatic cancer. The 2.3-kb mRNA of the gene, named TMPRSS3, is strongly expressed in a subset of pan- creatic cancer and various other cancer tissues, and its expression corre- lates with the metastatic potential of

Christine Wallrapp; Susanne Hahnel; Friederike Muller-Pillasch; Beata Burghardt; Takeshi Iwamura; Manuel Ruthenburger; Markus M. Lerch; Guido Adler; Thomas M. Gress

2000-01-01

405

Purification, Characterization, and Heterologous Expression in Fusarium venenatum of a Novel Serine Carboxypeptidase from Aspergillus oryzae  

Microsoft Academic Search

A novel serine carboxypeptidase (EC 3.4.16.1) was found in an Aspergillus oryzae fermentation broth and was purified to homogeneity. This enzyme has a molecular weight of ca. 67,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and its specific activity is 21 U\\/mg for carbobenzoxy (Z)-Ala-Glu at pH 4.5 and 25°C. It has a ratio of bimolecular constants for Z-Ala-Lys

ALEXANDER M. BLINKOVSKY; TONY BYUN; KIMBERLY M. BROWN; ELIZABETH J. GOLIGHTLY; Novo Nordisk

1999-01-01

406

Purification and molecular cloning of a novel serine protease from the centipede, Scolopendra subspinipes mutilans  

Microsoft Academic Search

A novel serine protease, named as scolonase, was purified and characterized from the tissue of the Korean centipede, Scolopendra subspinipes mutilans. Purified scolonase showed an apparent molecular weight of 25 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and an isoelectric point of 4.8 on isoelectric focusing gel. Scolonase was able to preferentially hydrolyze arginine over lysine at the cleavage

Weon-Kyoo You; Young-Doug Sohn; Ki-Yong Kim; Doo-Hong Park; Yangsoo Jang; Kwang-Hoe Chung

2004-01-01

407

In vivo decomposition of phosphoserine and serine in noncollagenous protein from human dentin  

Microsoft Academic Search

Summary  HCl-soluble proteins in human dentin ranging in age from 3 to 45 years exhibit amino acid compositional changes consistent\\u000a with ?-elimination and hydrolysis of phosphoserine as well as dehydration and aldol cleavage of serine. This is the first\\u000a evidence of nonenzymatic mechanisms forin vivo degradation of hydroxy and substituted hydroxy amino acids in dentin. Decomposition of phosphoseryl residues reduces the

Patricia M. Masters

1985-01-01

408

Frequent Alterations in the Expression of Serine\\/Threonine Kinases in Human Cancers  

Microsoft Academic Search

Protein kinases constitute a large family of regulatory enzymes involved in the homeostasis of virtually every cellular process. Subversion of protein kinases has been frequently implicated in malignant transformation. Within the family, serine\\/threonine kinases (STK) have received comparatively lesser attention, vis-a-vis tyrosine kinases, in terms of their involvement in human cancers. Here, we report a large-scale screening of 125 STK,

Maria Capra; Paolo Giovanni Nuciforo; Stefano Confalonieri; Micaela Quarto; Manuela Nebuloni; Renzo Boldorini; Francesco Pallotti; Giuseppe Viale; Mikhail L. Gishizky; Giulio F. Draetta

2006-01-01

409

Site-Directed Mutagenesis in the Study of Serine Hydroxy methyltransf erase  

Microsoft Academic Search

\\u000a Abstract  Site-directed mutagenesis techniques have been applied to theglyA gene ofE. Coli coding for serine hydroxymethyltransferase, in order to substitute amino acid residues known to be at the active site of\\u000a the enzyme. Two high efficiency mutagenesis methods have been used that specifically select,in vivo orin vitro, mutant DNA with respectto the wild-type one.

Elena Fattori; Sebastiana Angelaccio; Stefano Pascarella; Francesco Bossa; Donatella Barra; Verne Schirch; Corrisp M. Brunori

1990-01-01

410

Site-Directed Mutagenesis Techniques in the Study of Escherichia coliSerine Hydroxymethyltransferase  

Microsoft Academic Search

The 3340-bp fragment containing theEscherichia coli glyA gene coding for serine hydroxymethyltransferase was reduced in size by PCR, and the 1600-bp fragment obtained was cloned into the vector pBR322 in both orientations (5?–3? and 3?–5?). This DNA manipulation allowed us to perform site-directed mutagenesis by PCR on theglyA gene. To overcome the problem of the presence of wild-type protein in

Sandra Iurescia; Ivano Condò; Sebastiana Angelaccio; Sonia Delle Fratte; Francesco Bossa

1996-01-01

411

Neurobiology through the looking-glass: d-serine as a new glial-derived transmitter  

Microsoft Academic Search

d-Amino acids have been known to be present in bacteria for more than 50 years, but only recently they were identified in mammals. The occurrence of d-amino acids in mammals challenge classic concepts in biology in which only l-amino acids would be present or thought to play important roles. Recent discoveries uncovered a role of endogenous d-serine as a putative

Herman Wolosker; Rogerio Panizzutti; Joari De Miranda

2002-01-01

412

Cloning and sequencing of the serine dehydrogenase gene from Agrobacterium tumefaciens.  

PubMed

The structural gene for NADP+-dependent serine dehydrogenase [EC 1.1.1.-] from Agrobacterium tumefaciens ICR 1600 was cloned into Escherichia coli cells and its complete DNA sequence was analyzed. The gene encodes a polypeptide containing 249 amino acid residues. The enzyme had high sequence similarity to short-chain alcohol dehydrogenases from bacteria and unknown proteins of Haemophilus influenzae, Escherichia coli, and Saccharomyces cerevisiae. PMID:12092831

Fujisawa, Hisae; Nagata, Shinji; Chowdhury, Emran Kabir; Matsumoto, Miki; Misono, Haruo

2002-05-01

413

Regulation of Interferon Regulatory Factor3 by the Hepatitis C Virus Serine Protease  

Microsoft Academic Search

Persistent infections with hepatitis C virus (HCV) are likely to depend on viral inhibition of host defenses. We show that the HCV NS3\\/4A serine protease blocks the phosphorylation and effector action of interferon regulatory factor-3 (IRF-3), a key cellular antiviral signaling molecule. Disruption of NS3\\/4A protease function by mutation or a ketoamide peptidomimetic inhibitor relieved this blockade and restored IRF-3

Eileen Foy; Kui Li; Chunfu Wang; Rhea Sumpter; Masanori Ikeda; Stanley M. Lemon; Michael Gale

2003-01-01

414

Taraxalisin – a serine proteinase from dandelion Taraxacum officinale Webb s.l  

Microsoft Academic Search

Latex of dandelion roots contains a serine proteinase that hydrolyzes a chromogenic peptide substrate Glp-Ala-Ala-Leu-pNA optimally at pH 8.0. Maximal activity of the proteinase in the roots is attained in April, at the beginning of plant development after the winter period. The protease was isolated by ammonium sulfate precipitation of the root extract followed by affinity chromatography on a Sepharose-Ala-Ala-Leu-mrp

G. N. Rudenskaya; A. M. Bogacheva; A. Preusser; A. V. Kuznetsova; Ya. E. Dunaevsky; B. N. Golovkin; V. M. Stepanov

1998-01-01

415

Evidence for possible involvement of an elastolytic serine protease in aspergillosis.  

PubMed Central

A number of isolates of Aspergillus fumigatus obtained from the hospital environment produced extracellular elastolytic activity. This activity was found to be catalyzed by a single 33-kDa protein which was purified and characterized to be a serine protease. A. fumigatus, when grown on the insoluble structural material obtained from murine and bovine lung, produced the same extracellular 33-kDa elastolytic protease, indicating that this enzyme is likely to be produced when the organism infects the lung. Polymerase chain reaction with an oligonucleotide primer based on the N-terminal amino acid sequence of the elastolytic enzyme yielded a cDNA which was cloned and sequenced. The active serine motif showed more similarity to subtilisin than to mammalian elastase. The amino acid sequence showed 80% identity to the alkaline protease from Aspergillus oryzae. Screening of hospital isolates of Aspergillus flavus showed great variation in the production of elastolytic activity and a much lower level of activity than that produced by A. fumigatus. The elastolytic protease from A. flavus was shown to be a serine protease susceptible to modification and inactivation by active serine and histidine-directed reagents. This protease cross-reacted with the antibodies prepared against the elastolytic protease from A. fumigatus. Immunogold localization of the elastolytic enzyme showed that A. fumigatus germinating and penetrating into the lungs of neutropenic mice secreted the elastolytic protease. An elastase-deficient mutant generated from a highly virulent isolate of A. fumigatus caused drastically reduced mortality when nasally introduced into the lung of neutropenic mice. All of the evidence suggests that extracellular elastolytic protease is a significant virulence factor in invasive aspergillosis. Images

Kolattukudy, P E; Lee, J D; Rogers, L M; Zimmerman, P; Ceselski, S; Fox, B; Stein, B; Copelan, E A

1993-01-01

416

Assessment of coronary plaque collagen with polarization sensitive optical coherence tomography (PS-OCT)  

NASA Astrophysics Data System (ADS)

Current evidence indicates that most plaques classified as vulnerable or ruptured plaques do not lead to unstable angina or myocardial infarction. Improved methods are needed to risk stratify plaques to identify those which lead to most acute coronary syndromes. Collagen depletion in the intima overlying lipid collections appears to be a critical component of unstable plaques. In this study, we use polarization sensitive optical coherence tomography (PS-OCT) for the assessment of coronary plaque collagen. Collagen is birefringent, meaning that different polarization states travel through it at different velocities. Changes in PS-OCT images are a measure of tissue birefringence. Twenty-two coronary artery segments were imaged with PS-OCT and analyzed by picrosirius staining (a measure of collagen intensity and fiber size) and trichrome blue. The regression plot between PS-OCT changes and measured collagen yielded a correlation coefficient value of 0.475 (p<0.002). Good correlation was noted between two blinded investigators both with respect to PS-OCT measurements as well as luminosity as assessed by picrosirius. The predictive value of a PS-OCT measurement of negligible birefringence (less than 33% change) for minimal collagen was 93% while the predictive value of high birefringence (greater than 66% change) for high collagen concentrations was 89%. The effect of fiber type (chemical composition) was minimal relative to the effect due to fiber concentration. The capability of PS-OCT to assess plaque collagen content, in addition to its ability to generate high resolution structural assessments, make it a potentially powerful technology for identifying high risk plaques.

Giattina, Susanne D.; Courtney, Brian K.; Herz, Paul R.; Harman, Michelle; Shortkroff, Sonya; Stamper, Debra L.; Liu, Bin; Fujimoto, James G.; Brezinski, Mark E.

2006-03-01

417

Serine phosphorylation regulates disabled-1 early isoform turnover independently of Reelin  

PubMed Central

The Reelin-Disabled 1 (Dab1) signaling pathway plays an important role in neuronal cell migration during brain development. Dab1, an intracellular adapter protein which is tyrosine phosphorylated upon Reelin stimulation, has been directly implicated in the transmission and termination of Reelin-mediated signaling. Two main forms of Dab1 have been identified in the developing chick retina, an early isoform (Dab1-E) expressed in progenitor cells and a late isoform (Dab1-L, a.k.a. Dab1) expressed in differentiated cells. Dab1-E is missing two Src family kinase (SFK) phosphorylation sites that are critical for Reelin-Dab1 signaling and is not tyrosine phosphorylated. We have recently demonstrated a role for Dab1-E in the maintenance of retinal progenitor cells. Here, we report that Dab1-E is phosphorylated at serine/threonine residues independent of Reelin. Cdk2, highly expressed in retinal progenitor cells, mediates Dab1-E phosphorylation at serine 475 which in turn promotes ubiquitination-triggered proteasome degradation of Dab1-E. Inhibition of protein phosphatase 1 and/or protein phosphatase 2A leads to increased Dab1-E instability. We propose that Dab1 turnover is regulated by both Reelin-independent serine/threonine phosphorylation and Reelin-dependent tyrosine phosphorylation.

Gao, Zhihua; Godbout, Roseline

2013-01-01

418

Tyrosine and serine phosphorylation of ?-synuclein have opposing effects on neurotoxicity and soluble oligomer formation  

PubMed Central

Mutations in the neuronal protein ?-synuclein cause familial Parkinson disease. Phosphorylation of ?-synuclein at serine 129 is prominent in Parkinson disease and influences ?-synuclein neurotoxicity. Here we report that ?-synuclein is also phosphorylated at tyrosine 125 in transgenic Drosophila expressing wild-type human ?-synuclein and that this tyrosine phosphorylation protects from ?-synuclein neurotoxicity in a Drosophila model of Parkinson disease. Western blot analysis of fly brain homogenates showed that levels of soluble oligomeric species of ?-synuclein were increased by phosphorylation at serine 129 and decreased by tyrosine 125 phosphorylation. Tyrosine 125 phosphorylation diminished during the normal aging process in both humans and flies. Notably, cortical tissue from patients with the Parkinson disease–related synucleinopathy dementia with Lewy bodies showed less phosphorylation at tyrosine 125. Our findings suggest that ?-synuclein neurotoxicity in Parkinson disease and related synucleinopathies may result from an imbalance between the detrimental, oligomer-promoting effect of serine 129 phosphorylation and a neuroprotective action of tyrosine 125 phosphorylation that inhibits toxic oligomer formation.

Chen, Li; Periquet, Magali; Wang, Xu; Negro, Alessandro; McLean, Pamela J.; Hyman, Bradley T.; Feany, Mel B.

2009-01-01

419

Structure of haptoglobin heavy chain and other serine protease homologs by comparative model building  

SciTech Connect

Proteins often occur in families whose structure is closely similar, even though the proteins may come from widely different sources and have quite distinct functions. It would be useful to be able to construct the three-dimensional structure of these proteins from the known structure of one or more of them without having to solve the structure of each protein ab initio. We have been using comparative model building to derive the structure of an unusual protein of the trypsin-like serine protease family. We have recently extended this comparison to include other serine protease homologs for which a primary structure is available. To generate structures for the different members of the serine protease family, it is necessary to extract the common structural features of the molecule. Fortunately, three independently determined protein structures are available: schymotrypsin, trypsin, and elastase. These three structures were compared in detail and the structurally conserved regions in all three, mainly the BETA-sheet and the ..cap alpha..-helix, were identified. The variable portions occur in the loops on the surface of the molecule. By using these structures, the primary sequences of these three proteins were aligned. From this alignment, it is clear that sequence homology between the proteins occurs mainly in the structurally conserved regions of the molecule, while the variable portions show very little sequence homology.

Grer, J.

1980-10-01

420

Serine/threonine/tyrosine protein kinase phosphorylates oleosin, a regulator of lipid metabolic functions.  

PubMed

Plant oils are stored in oleosomes or oil bodies, which are surrounded by a monolayer of phospholipids embedded with oleosin proteins that stabilize the structure. Recently, a structural protein, Oleosin3 (OLE3), was shown to exhibit both monoacylglycerol acyltransferase and phospholipase A(2) activities. The regulation of these distinct dual activities in a single protein is unclear. Here, we report that a serine/threonine/tyrosine protein kinase phosphorylates oleosin. Using bimolecular fluorescence complementation analysis, we demonstrate that this kinase interacts with OLE3 and that the fluorescence was associated with chloroplasts. Oleosin-green fluorescent protein fusion protein was exclusively associated with the chloroplasts. Phosphorylated OLE3 exhibited reduced monoacylglycerol acyltransferase and increased phospholipase A(2) activities. Moreover, phosphatidylcholine and diacylglycerol activated oleosin phosphorylation, whereas lysophosphatidylcholine, oleic acid, and Ca(2+) inhibited phosphorylation. In addition, recombinant peanut (Arachis hypogaea) kinase was determined to predominantly phosphorylate serine residues, specifically serine-18 in OLE3. Phosphorylation levels of OLE3 during seed germination were determined to be higher than in developing peanut seeds. These findings provide direct evidence for the in vivo substrate selectivity of the dual-specificity kinase and demonstrate that the bifunctional activities of oleosin are regulated by phosphorylation. PMID:22434039

Parthibane, Velayoudame; Iyappan, Ramachandiran; Vijayakumar, Anitha; Venkateshwari, Varadarajan; Rajasekharan, Ram

2012-03-20

421

Effect of serine/threonine kinase inhibitors on motility of human lymphocytes and U937 cells.  

PubMed Central

Mononuclear cell migration across the endothelium and through connective tissue into inflammatory sites is a multi-step process. After adhesion to the endothelium, there is an initial change in shape from spherical to irregular, followed by the migratory phase itself in which the cells constantly change in shape. In this paper we have investigated the possibility that the shape-changing in this latter phase is controlled by serine/threonine phosphorylation. For this purpose, we used a spontaneously shape-changing variant of U937 monocytoid cells as well as human peripheral blood lymphocytes that had been previously activated by anti-CD3. To test the role of phosphorylation in shape-changing, a wide range of serine/threonine kinase inhibitors was tested, including ML-7, KT5720, KT823, H7, H8, staurosporine, calphostin C, sphingosine, bisindolylmaleimide, chelerythrine and KN-62. Only those compounds which inhibited protein kinase C prevented lymphocyte and U937 shape-change and transmigration across polycarbonate filters. However, one specific protein kinase C inhibitor, bisindolylmaleimide, stimulated lymphocyte shape-change. In conclusion, these studies show that activation of a serine/threonine kinase is necessary for the constant shape-changing required for motility of mononuclear cells. The kinase may be a protein kinase C isotype or a closely related enzyme. Images Figure 1

Thorp, K M; Southern, C; Matthews, N

1994-01-01

422

[Interaction between gabapentin and D-serin in the formalin orofacial test].  

PubMed

Gabapentin is a useful agent for the relief of trigeminal neuralgia and orofacial phantom pain. However, there is scarce information on the gabapentin analgesic effect in orofacial pain models. We tested the analgesic action of gabapentin on the formalin-induced face grooming in the rat, an orofacial pain paradigm. IP Gabapentin (10 mg/kg), induced a drastic reduction in face grooming during phase I and II, indicating a clear-cut antinociceptive effect. However, at 1 mg/kg, gabapentin had an analgesic effect only on phase I. D-serine (100 microg, ICV) was silent when given alone and did not antagonize the antinociceptive effect of gabapentin. On the contrary, gabapentin 1 mg/kg plus D-serine significantly reduced face grooming in phase II. These results show a difference between gabapentin induced orofacial analgesia and previous studies showing gabapentin-induced hind paw analgesia in the formalin test, only during phase II, as well as D-serine antagonism of gabapentin. The results are discussed in terms of different pain processing of hind paw, versus orofacial nociceptive stimulation. PMID:20306721

Quiñónez, Belkis; Silva, Elizabeth; González, Luis E; Hernández, Luis

2009-12-01

423

Serine/Threonine/Tyrosine Protein Kinase Phosphorylates Oleosin, a Regulator of Lipid Metabolic Functions1[OA  

PubMed Central

Plant oils are stored in oleosomes or oil bodies, which are surrounded by a monolayer of phospholipids embedded with oleosin proteins that stabilize the structure. Recently, a structural protein, Oleosin3 (OLE3), was shown to exhibit both monoacylglycerol acyltransferase and phospholipase A2 activities. The regulation of these distinct dual activities in a single protein is unclear. Here, we report that a serine/threonine/tyrosine protein kinase phosphorylates oleosin. Using bimolecular fluorescence complementation analysis, we demonstrate that this kinase interacts with OLE3 and that the fluorescence was associated with chloroplasts. Oleosin-green fluorescent protein fusion protein was exclusively associated with the chloroplasts. Phosphorylated OLE3 exhibited reduced monoacylglycerol acyltransferase and increased phospholipase A2 activities. Moreover, phosphatidylcholine and diacylglycerol activated oleosin phosphorylation, whereas lysophosphatidylcholine, oleic acid, and Ca2+ inhibited phosphorylation. In addition, recombinant peanut (Arachis hypogaea) kinase was determined to predominantly phosphorylate serine residues, specifically serine-18 in OLE3. Phosphorylation levels of OLE3 during seed germination were determined to be higher than in developing peanut seeds. These findings provide direct evidence for the in vivo substrate selectivity of the dual-specificity kinase and demonstrate that the bifunctional activities of oleosin are regulated by phosphorylation.

Parthibane, Velayoudame; Iyappan, Ramachandiran; Vijayakumar, Anitha; Venkateshwari, Varadarajan; Rajasekharan, Ram

2012-01-01

424

Attachment site recognition and regulation of directionality by the serine integrases  

PubMed Central

Serine integrases catalyze the integration of bacteriophage DNA into a host genome by site-specific recombination between ‘attachment sites’ in the phage (attP) and the host (attB). The reaction is highly directional; the reverse excision reaction between the product attL and attR sites does not occur in the absence of a phage-encoded factor, nor does recombination occur between other pairings of attachment sites. A mechanistic understanding of how these enzymes achieve site-selectivity and directionality has been limited by a lack of structural models. Here, we report the structure of the C-terminal domains of a serine integrase bound to an attP DNA half-site. The structure leads directly to models for understanding how the integrase-bound attP and attB sites differ, why these enzymes preferentially form attP × attB synaptic complexes to initiate recombination, and how attL × attR recombination is prevented. In these models, different domain organizations on attP vs. attB half-sites allow attachment-site specific interactions to form between integrase subunits via an unusual protruding coiled-coil motif. These interactions are used to preferentially synapse integrase-bound attP and attB and inhibit synapsis of integrase-bound attL and attR. The results provide a structural framework for understanding, testing and engineering serine integrase function.

Rutherford, Karen; Yuan, Peng; Perry, Kay; Sharp, Robert; Van Duyne, Gregory D.

2013-01-01

425

Characterization of a Mn sup 2+ -dependent membrane serine kinase that is activated by tyrosine phosphorylation  

SciTech Connect

It is hypothesized that the insulin receptor (IR) tyrosine kinase may directly phosphorylate and activate one or more serine kinases. The identities of such serine kinases as well as their modes of activation are unclear. The authors have described a serine kinase from rat liver membranes that copurifies with the IR on wheat germ agglutinin (WGA)-sepharose. The kinase is activated after phosphorylation of the WGA-sepharose-purified fraction by casein kinase-1, casein kinase-2, or casein kinase-3. A tyrosine kinase, possibly IR tyrosine kinase, also participates in the activation process since a phosphotyrosine phosphatase inhibitor such as vanadate, p-nitrophenyl phosphate, or phosphotyrosine is required in reaction mixtures for activation to be observed. By contrast, phosphoserine and phosphothreonine do not support activation. The activated kinase can use IR {beta}-subunit, myelin basic protein (MBP), and histones as substrates. IR {beta}-subunit phosphorylation was stimulated by MBP, histones, and polylysine, and inhibited by heparin and poly(glu, tyr). The kinase prefers Mn{sup 2+} over Mg{sup 2+} as a metal cofactor.

Singh, T.J. (Univ. of Waterloo, Ontario (Canada))

1991-03-11

426

New families of carboxyl peptidases: serine-carboxyl peptidases and glutamic peptidases.  

PubMed

Peptidases or proteinases are now classified into seven families based on the nature of the catalytic residues [MEROPS-the peptidase database (http://merops.sanger.ac.uk/)]. They are aspartic- (first described in 1993), cysteine- (1993), serine- (1993) metallo- (1993), threonine- (1997), glutamic- (2004) and asparagine-peptidase (2010). By using an S-PI (pepstatin Ac) as a probe, a new subfamily of serine peptidase, serine-carboxyl peptidase (sedolisin) was discovered in 2001. In addition, the sixth family of peptidase, glutamic peptidase (eqolisin) was also discovered in 2004. The former peptidase is widely distributed in nature from archea to mammals, including humans. One of these enzymes is related to a human fatal hereditable disease, Batten disease. In contrast, the distribution of the latter peptidases is limited, with most of them found in human or plant pathogenic fungi. One such enzyme was isolated from a fungal infection in an HIV-infected patient. In this review, the background of the findings, and crystal structures, catalytic mechanisms, substrates specificities and distribution of the new peptidase families are described. PMID:22016395

Oda, Kohei

2011-10-19

427

A role for glycosylated Serine-rich repeatproteins in Gram-positive bacterial pathogenesis  

PubMed Central

Summary Bacterial attachment to host surfaces is a pivotal event in the biological and infectious processes of both commensal and pathogenic bacteria, respectively. Serine-rich Repeat Proteins (SRRPs) are a family of adhesins in Gram-Positive bacteria that mediate attachment to a variety of host and bacterial surfaces. As such, they contribute towards a wide-range of diseases including sub-acute bacterial endocarditis, community-acquired pneumonia, and meningitis. SRRPs are unique in that they are glycosylated, require a non-canonical Sec-translocase for transport, and are largely composed of a domain containing hundreds of alternating serine residues. These serine-rich repeats are thought to extend a unique non-repeat (NR) domain outward away from the bacterial surface to mediate adhesion. Thus far, NR domains have been determined to bind to sialic acid moieties, keratins, or other NR domains of a similar SRRP. This review summarizes how this important family of bacterial adhesins mediates bacterial attachment to host and bacterial cells, contributes to disease pathogenesis, and might be targeted for pharmacological intervention or used as novel protective vaccine antigens. This review also highlights recent structural findings on the NR domains of these pr