The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Paul J Hergenrother - One of the best experts on this subject based on the ideXlab platform.
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identification of promiscuous small molecule activators in high throughput Enzyme Activation screens
Journal of Medicinal Chemistry, 2008Co-Authors: David R Goode, Ryan K Totten, James T Heeres, Paul J HergenrotherAbstract:It is recognized that high-throughput Enzyme inhibition screens often return nonspecific inhibitors as "hits". Recently, high-throughput screens for Enzyme activators have led to the identification of several compounds with novel and potent biological activity. Here, we show that Enzyme Activation screens can also uncover compounds that activate multiple Enzymes in a nonspecific fashion. Described herein are the general structural features of such compounds and methods to differentiate between specific and general Enzyme Activation.
Anthony Persechini - One of the best experts on this subject based on the ideXlab platform.
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effects of combined phosphorylation at ser 617 and ser 1179 in endothelial nitric oxide synthase on ec50 ca2 values for calmodulin binding and Enzyme Activation
Journal of Biological Chemistry, 2009Co-Authors: Quangkim Tran, Jared Leonard, D J Black, Owen W Nadeau, Igor G Boulatnikov, Anthony PersechiniAbstract:We have investigated the possible biochemical basis for enhancements in NO production in endothelial cells that have been correlated with agonist- or shear stress-evoked phosphorylation at Ser-1179. We have found that a phosphomimetic substitution at Ser-1179 doubles maximal synthase activity, partially disinhibits cytochrome c reductase activity, and lowers the EC50(Ca2+) values for calmodulin binding and Enzyme Activation from the control values of 182 ± 2 and 422 ± 22 nm to 116 ± 2 and 300 ± 10 nm. These are similar to the effects of a phosphomimetic substitution at Ser-617 (Tran, Q. K., Leonard, J., Black, D. J., and Persechini, A. (2008) Biochemistry 47, 7557–7566). Although combining substitutions at Ser-617 and Ser-1179 has no additional effect on maximal synthase activity, cooperativity between the two substitutions completely disinhibits reductase activity and further reduces the EC50(Ca2+) values for calmodulin binding and Enzyme Activation to 77 ± 2 and 130 ± 5 nm. We have confirmed that specific Akt-catalyzed phosphorylation of Ser-617 and Ser-1179 and phosphomimetic substitutions at these positions have similar functional effects. Changes in the biochemical properties of eNOS produced by combined phosphorylation at Ser-617 and Ser-1179 are predicted to substantially increase synthase activity in cells at a typical basal free Ca2+ concentration of 50–100 nm.
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phosphorylation within an autoinhibitory domain in endothelial nitric oxide synthase reduces the ca2 concentrations required for calmodulin to bind and activate the Enzyme
Biochemistry, 2008Co-Authors: Quangkim Tran, Jared Leonard, D J Black, Anthony PersechiniAbstract:We have investigated the effects of phosphorylation at Ser-617 and Ser-635 within an autoinhibitory domain (residues 595-639) in bovine endothelial nitric oxide synthase on Enzyme activity and the Ca (2+) dependencies for calmodulin binding and Enzyme Activation. A phosphomimetic S617D substitution doubles the maximum calmodulin-dependent Enzyme activity and decreases the EC 50(Ca (2+)) values for calmodulin binding and Enzyme Activation from the wild-type values of 180 +/- 2 and 397 +/- 23 nM to values of 109 +/- 2 and 258 +/- 11 nM, respectively. Deletion of the autoinhibitory domain also doubles the maximum calmodulin-dependent Enzyme activity and decreases the EC 50(Ca (2+)) values for calmodulin binding and calmodulin-dependent Enzyme Activation to 65 +/- 4 and 118 +/- 4 nM, respectively. An S635D substitution has little or no effect on Enzyme activity or EC 50(Ca (2+)) values, either alone or when combined with the S617D substitution. These results suggest that phosphorylation at Ser-617 partially reverses suppression by the autoinhibitory domain. Associated effects on the EC 50(Ca (2+)) values and maximum calmodulin-dependent Enzyme activity are predicted to contribute equally to phosphorylation-dependent enhancement of NO production during a typical agonist-evoked Ca (2+) transient, while the reduction in EC 50(Ca (2+)) values is predicted to be the major contributor to enhancement at resting free Ca (2+) concentrations.
Joseph B Bolen - One of the best experts on this subject based on the ideXlab platform.
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syk protein tyrosine kinase is regulated by tyrosine phosphorylated iga ig 3 immunoreceptor tyrosine Activation motif binding and autophosphorylation
Journal of Biological Chemistry, 1995Co-Authors: R B Rowley, Anne L Burkhardt, Hannguang Chao, Gary R Matsueda, Joseph B BolenAbstract:Syk is a cytoplasmic protein-tyrosine kinase containing two amino-terminal Src homology 2 domains that is activated following ligation of the B cell antigen receptor. Syk Activation in B cells correlates with Syk tyrosine phosphorylation as well as with Syk SH2-mediated association with the tyrosine-phosphorylated Igα and Igβ B cell antigen receptor subunits. Tyrosine-phosphorylated peptide 20-mers representing Igα and Igβ immunoreceptor tyrosine Activation motifs were synthesized and found to stimulate the specific activity of Syk by as much as 10-fold in vitro. Maximal phosphopeptide-induced Syk Activation required both Syk SH2 domains and phosphorylation of both tyrosine residues present in the immunoreceptor tyrosine Activation motif. The biochemical mechanism responsible for the phosphopeptide-induced Syk Enzyme Activation appears to be a function of Syk autophosphorylation. Our observations suggest the association of Syk tandem SH2 domains with the tyrosine-phosphorylated Igα and/or Igβ immunoreceptor tyrosine Activation motifs in B cells stimulates Syk autophosphorylation leading to Syk Enzyme Activation.
Francesca Buricchi - One of the best experts on this subject based on the ideXlab platform.
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protein tyrosine phosphorylation and reversible oxidation two cross talking posttranslation modifications
Antioxidants & Redox Signaling, 2007Co-Authors: Paola Chiarugi, Francesca BuricchiAbstract:In addition to protein phosphorylation, redox-dependent posttranslational modification of proteins is emerging as a key signaling system, conserved throughout evolution, and influencing many aspects of cellular homeostasis. Recent data have provided new insight about the interplay between phosphorylation- and redox-dependent signaling, and reactive oxygen species have been included among intracellular signal transducers of growth factor and extracellular matrix receptors. Both tyrosine phosphorylation and thiol oxidation are reversible and dynamic, and this review will particularly focus on the cross-talk between these posttranslational protein regulatory means. Although these modifications share their reversibility, their effects on enzymatic activity of protein tyrosine phosphatases (PTPs) and protein tyrosine kinases (PTKs) may be even opposite. Indeed, while tyrosine phosphorylation is frequently correlated to Enzyme Activation, thiol oxidation leads to inActivation of PTPs and to superActivation of P...
Akira Takeshita - One of the best experts on this subject based on the ideXlab platform.
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pathogenic role of oxidative stress in vascular angiotensin converting Enzyme Activation in long term blockade of nitric oxide synthesis in rats
Hypertension, 1999Co-Authors: Makoto Usui, Kensuke Egashira, Shiro Kitamoto, Masamichi Koyanagi, Makoto Katoh, Chu Kataoka, Hiroaki Shimokawa, Akira TakeshitaAbstract:Abstract —Inhibition of nitric oxide (NO) synthesis with N ω-nitro-l-arginine methyl ester (L-NAME) activates vascular angiotensin-converting Enzyme (ACE) and causes oxidative stress. We investigated the role of oxidative stress in the pathogenesis of ACE Activation in rats. Studies involved aortas of rats receiving no treatment, L-NAME, L-NAME plus l-arginine, or L-NAME plus an antioxidant drug ( N -acetylcysteine, allopurinol, or ebselen) for 7 days. L-NAME significantly increased oxidative stress (O2−) and ACE activity. The increased O2− production was normalized by removal of endothelium. Immunohistochemistry showed the increased ACE activity in the endothelial layer. Treatment with antioxidant drugs did not affect the L-NAME–induced increase in systolic arterial pressure but did prevent increases in vascular O2− production and ACE activity. These results implicate oxidative stress in the pathogenesis of vascular ACE Activation in rats with long-term inhibition of NO synthesis. The observed effects of antioxidant drugs on ACE Activation do not appear to involve the hypertension induced by L-NAME.