RGD Reference Report - Novel kinetics of mammalian glutathione synthetase: characterization of gamma-glutamyl substrate cooperative binding. - Rat Genome Database

Send us a Message



Submit Data |  Help |  Video Tutorials |  News |  Publications |  Download |  REST API |  Citing RGD |  Contact   

Novel kinetics of mammalian glutathione synthetase: characterization of gamma-glutamyl substrate cooperative binding.

Authors: Luo, JL  Huang, CS  Babaoglu, K  Anderson, ME 
Citation: Luo JL, etal., Biochem Biophys Res Commun. 2000 Aug 28;275(2):577-81.
RGD ID: 1599340
Pubmed: (View Article at PubMed) PMID:10964706
DOI: Full-text: DOI:10.1006/bbrc.2000.3337

Glutathione (GSH) synthetase [L-gamma-glutamyl-L-cysteinyl:glycine ligase (ADP-forming), EC 6.3.2.3] catalyzes the final step in GSH biosynthesis. Mammalian glutathione synthetase is a homodimer with each subunit containing an active site. We report the detailed kinetic data for purified recombinant rat glutathione synthetase. It has the highest specific activity (11 micromol/min/mg) reported for any mammalian glutathione synthetase. The apparent K(m) values for ATP and glycine are 37 and 913 microM, respectively. The Lineweaver-Burk double reciprocal plot for gamma-glutamyl substrate binding revealed a departure from linearity indicating cooperative binding. Quantitative analysis of the kinetic results for gamma-glutamyl substrate binding gives a Hill coefficient (h) of 0. 576, which shows the negative cooperativity. Neither ATP, the other substrate involved in forming the enzyme-bound gamma-glutamyl phosphate intermediate, nor glycine, which attacks this intermediate to form GSH, exhibit any cooperativity. The cooperative binding of gamma-glutamyl substrate is not affected by ATP concentration. Thus, mammalian glutathione synthetase is an allosteric enzyme.

Annotation

Gene Ontology Annotations    

Biological Process

Molecular Function

Objects Annotated

Genes (Rattus norvegicus)
Gss  (glutathione synthetase)


Additional Information