title: Selective inhibition of an enzyme in crude cell extracts. The use of subunits modified with a half-of-the-sites reagent.
abstract: Yeast glyceraldehyde-3-phosphate dehydrogenase carboxymethylated at four active-site cysteine residues was incubated with a crude extract of baker's yeast. This resulted in a loss of the glyceraldehyde-3-phosphate dehydrogenase activity initially present in the extract. The extent of inactivation depended upon the ratio modified enzyme/enzyme present in the extract. Under appropriate conditions 63.1% inactivation of glyceraldehyde-3-phosphate dehydrogenase in crude extract could be achieved. The observed effect is explained in terms of hybridization between the carboxymethylated dimers of the purified enzyme and dimeric species of glyceraldehyde-3-phosphate dehydrogenase present in the crude extract, the inactivation being due to the influence of the half-of-the-sites reagent transmitted via the interdimeric contacts.
mesh_terms: D000818:Animals; D001051:Apoenzymes / Q000037:antagonists & inhibitors; D001665:Binding Sites; D003545:Cysteine; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D046911:Macromolecular Substances; D008745:Methylation; D009132:Muscles / Q000201:enzymology; D055503:Protein Multimerization; D011817:Rabbits; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
chemical_list: D001051:Apoenzymes; D046911:Macromolecular Substances; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D003545:Cysteine