Topic
Tyrosine
About: Tyrosine is a research topic. Over the lifetime, 15918 publications have been published within this topic receiving 706571 citations. The topic is also known as: Tyr & (2S)-2-amino-3-(4-hydroxyphenyl)propanoic acid.
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TL;DR: This study explores the proposal that PTPs may be regulated by reversible reduction/oxidation involving cellular oxidants such as hydrogen peroxide (H2O2) and proposes a chemical mechanism for reversible inactivation involving a cysteine sulfenic acid intermediate.
Abstract: Protein tyrosine phosphatases (PTPs) catalyze the hydrolysis of phosphotyrosine from specific signal-transducing proteins. Although regulatory mechanisms for protein kinases have been described, no general mechanism for controlling PTPs has been demonstrated. Numerous reports have shown that cellular redox status plays an important role in tyrosine phosphorylation-dependent signal transduction pathways. This study explores the proposal that PTPs may be regulated by reversible reduction/oxidation involving cellular oxidants such as hydrogen peroxide (H2O2). Recent reports indicated that H2O2 is transiently generated during growth factor stimulation and that H2O2 production is concomitant with relevant tyrosine phosphorylation. By use of recombinant enzymes, the effects of H2O2 on three PTPs [PTP1, LAR (leukocyte antigen-related), and VHR (vaccinia H1-related)] and three distinct serine/threonine protein phosphatases (PPs: PP2Cα, calcineurin, and λ phosphatase) were determined. Hydrogen peroxide had no app...
937 citations
TL;DR: The fluorometric method is used to determine the amount of tyrosine in plasma from fasting patients with different disease states, as compared to the amountof the amino acid found in the plasma of normal fasting controls.
934 citations
TL;DR: It is established that oxidatively damaged protein is associated with aging and some diseases and nitration of tyrosine residues may contribute to peroxynitrite toxicity, as nitration precludes the phosphorylation or nucleotidylation of tyosine residues and thereby seriously compromises one of the most important mechanisms of cellular regulation and signal transduction.
Abstract: Highly reactive oxygen species that are formed during normal metabolism and under conditions of oxidative stress are able to oxidize proteins or convert lipid and carbohydrate derivatives to compounds that react with functional groups on proteins. Among other changes, these ROS-mediated reactions lead to the formation of protein carbonyl derivatives, which serves as a marker of ROS-mediated protein damage. On the basis of this marker, it is established that oxidatively damaged protein is associated with aging and some diseases. The accumulation of oxidatively damaged protein reflects the balance among a myriad of factors that govern the rates of ROS generation and the rate at which damaged protein is degraded. Peroxynitrite, which is formed under normal physiological conditions, is able to oxidize methionine residues in proteins and to nitrate tyrosine residues; however, its ability to do so is dependent on the availability of CO2, which stimulates the nitration of tyrosine residues but inhibits the oxidation of methionine residues. Nitration of tyrosine residues may contribute to peroxynitrite toxicity, as nitration precludes the phosphorylation or nucleotidylation of tyrosine residues and thereby seriously compromises one of the most important mechanisms of cellular regulation and signal transduction.
863 citations
TL;DR: It is found that the cdc25 sequence shows weak but significant homology to a phylogenetically diverse group of protein tyrosine phosphatases, and is a specific protein phosphatase that dephosphorylates tyrosines and possibly threonine residues on p34cdc2 and regulates MPF activation.
856 citations
TL;DR: Leucine, isoleucaine, and valine appear responsible for the effects of plasma amino or isoleucine andValine together, also were able to inhibit protein degradation and promote synthesis and five times normal plasma concentrations of the amino acids had larger effects.
839 citations