Sandbox Reserved 771: Difference between revisions

← Older edit Newer edit →

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA, Elliott Wyatt

@@ Line 4: / Line 4: @@
-'''Glutathione synthetase''' (GSS) is an homo-dimeric, ATP-depending <scene name='56/564047/Biological_assembly/2'>ligase</scene> responsible for the condensation of γ-Glutamylcysteine and glycine to form Glutathione during the second step of the glutathione biosynthesis pathway. Glutathione considered to be one of the most abundant and important antioxidants present in mammalian cells. In addition to protecting cells from the oxidative damage caused by free radicals, it is believed to be involved in the detoxification of xenobiotics, as well as membrane transport. Below, the direct enzyme catalysis step is shown in addition to the entire glutathione biosynthesis pathway and GSS's role in such a cycle.
+'''Glutathione synthetase''' (GSS) is an homo-dimeric, ATP-depending <scene name='56/564047/Biological_assembly/2'>ligase</scene> responsible for the condensation of γ-Glutamylcysteine and glycine to form Glutathione (GSH) during the second step of the glutathione biosynthesis pathway. Glutathione considered to be one of the most abundant and important antioxidants present in a wide range of cells - including bacterial, plant, and mammalian cells. In addition to protecting cells from the oxidative damage caused by free radicals, it is believed to be involved in the detoxification of xenobiotics, as well as membrane transport.
@@ Line 11: / Line 11: @@
 [[Image:cycle.jpg]]
-Glutathione Synthetase is the key enzyme involved in the ATP-dependent condensation of γ-Glutamylcysteine and glycine to form Glutathione during the second step of the glutathione biosynthesis pathway. The ATP-dependence of the catalysis qualifies GSS for inclusion into the ligase enzyme family. Further, a Hill constant of ~0.67 indicates that GSS exhibits negative cooperativity towards the substrate γ-Glutamylcysteine.
+Glutathione Synthetase is the key enzyme involved in the ATP-dependent condensation of γ-Glutamylcysteine and glycine to form Glutathione during the second step of the glutathione biosynthesis pathway. The condensation begins by binding of ATP to GSS in the presence of γ-Glutamylcysteine, to form an enzyme-bound acyl-phosphate that binds glycine and generates the enzyme-product complex. Dissociation of GSS from the E::P complex results in release of GSH, ADP, and inorganic phosphate (Pi). The ATP-dependence of the catalysis qualifies GSS for inclusion into the ligase enzyme superfamily. Further, a Hill constant of ~0.67 indicates that GSS exhibits negative cooperativity towards the substrate γ-Glutamylcysteine.