Role of the histidine 176 residue in glyceraldehyde-3-phosphate dehydrogenase as probed by site-directed mutagenesis.
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Soukri A, Mougin A, Corbier C, Wonacott A, Branlant C, Branlant G
Role of the histidine 176 residue in glyceraldehyde-3-phosphate dehydrogenase as probed by site-directed mutagenesis.
Biochemistry. 1989 Mar 21;28(6):2586-92.
- PubMed ID
- 2659073 [ View in PubMed]
- Abstract
The catalytically essential amino acid, histidine 176, in the active site of Escherichia coli glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been replaced with an asparagine residue by site-directed mutagenesis. The role of histidine 176 as a chemical activator, enhancing the reactivity of the thiol group of cysteine 149, has been demonstrated, with iodoacetamide as a probe. The esterolytic properties of GAPDH, illustrated by the hydrolysis of p-nitrophenyl acetate, have been also studied. The kinetic results favor a role for histidine 176 not only as a chemical activator of cysteine 149 but also as a hydrogen donor facilitating the formation of tetrahedral intermediates. These results support the hypothesis that histidine 176 plays a similar role during the oxidative phosphorylation of glyceraldehyde 3-phosphate.