Sandbox Reserved 771: Difference between revisions
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[[Image:Dimerized_color.jpg| | [[Image:Dimerized_color.jpg|right|400px]] | ||
'''Glutathione synthetase''' (GSS) is an homo-dimeric, ATP-depending ligase responsible for the condensation of γ-Glutamylcysteine and glycine to form Glutathione (GSH) during the second step of the glutathione biosynthesis pathway <ref>PMID:19672693</ref>. '''Glutathione''' is considered to be one of the most abundant and important antioxidants present across many bacterial (cyano- and proteobacteria), and all plant & mammalian cells <ref>http://www.ncbi.nlm.nih.gov/protein/NP_000169.1</ref>. In addition to protecting cells from the oxidative damage caused by free radicals, it is believed to be involved in the detoxification of xenobiotics, toxins in the blood, and even amino acid transport <ref>PMID:21683691</ref>. | '''Glutathione synthetase''' (GSS) is an homo-dimeric, ATP-depending ligase responsible for the condensation of γ-Glutamylcysteine and glycine to form Glutathione (GSH) during the second step of the glutathione biosynthesis pathway <ref>PMID:19672693</ref>. '''Glutathione''' is considered to be one of the most abundant and important antioxidants present across many bacterial (cyano- and proteobacteria), and all plant & mammalian cells <ref>http://www.ncbi.nlm.nih.gov/protein/NP_000169.1</ref>. In addition to protecting cells from the oxidative damage caused by free radicals, it is believed to be involved in the detoxification of xenobiotics, toxins in the blood, and even amino acid transport <ref>PMID:21683691</ref>. | ||
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==Substrate and ATP Binding Residues== | ==Substrate and ATP Binding Residues== | ||
<StructureSection load="2hgs" size="350" color="" frame="true" spin="on" Scene= align="right" caption='Human Glutathione Synthetase, [[2HGS]] ' > | |||
===Aspartate 458 <ref>PMID:21771585</ref>=== | ===Aspartate 458 <ref>PMID:21771585</ref>=== | ||
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'''Val44''' and '''Val45''' are two other residues which have been theorized to be important to the catalytic function of GSS due to their location on the dimerization site of the homogenous subunits. Early computer studies suggested that mutation to Val45 would have a larger detrimental effect than a mutation to Val44, and these predictions have since been verified by experimental studies. Differential scanning calorimetry has demonstrated that mutations to either of these two valines results in a loss of structural stability, with Val45 mutants being less stable than the Val44 mutants. Kinetic experiments suggest little effect on the affinity of GSS for γ-Glutamylcysteine by mutating one of these two residues, therefore it is assumed that the dimerization site is a part of the allosteric pathway rather than involved in the active site of the enzyme. It can be said with confidence, however, that they are integral to the stability of the biologically active protein. | '''Val44''' and '''Val45''' are two other residues which have been theorized to be important to the catalytic function of GSS due to their location on the dimerization site of the homogenous subunits. Early computer studies suggested that mutation to Val45 would have a larger detrimental effect than a mutation to Val44, and these predictions have since been verified by experimental studies. Differential scanning calorimetry has demonstrated that mutations to either of these two valines results in a loss of structural stability, with Val45 mutants being less stable than the Val44 mutants. Kinetic experiments suggest little effect on the affinity of GSS for γ-Glutamylcysteine by mutating one of these two residues, therefore it is assumed that the dimerization site is a part of the allosteric pathway rather than involved in the active site of the enzyme. It can be said with confidence, however, that they are integral to the stability of the biologically active protein. | ||
===Glycine Triad <ref>PMID:20800579</ref>=== | ===Glycine Triad <ref>PMID:20800579</ref>=== | ||
