Collect. Czech. Chem. Commun. 1980, 45, 1601-1607

Iodoacetate inactivation of rape alcohol dehydrogenase

Marie Stiborová and Sylva Leblová

Department of Biochemistry, Charles University, 128 40 Prague 2


Iodoacetate inactivates rape alcohol dehydrogenase (ADH, EC The inactivation rate follows the kinetics of the first order, is pH-dependent, and decreases below pH 7.5. Besides irreversible alkylation of the sulfhydryl groups of the enzyme iodoacetate also forms a reversible complex with rape ADH. The coenzyme (NAD) and its analogs (ATP, ADP, AMP) competitively protect the enzyme against alkylation; o-phenanthroline also protects the enzyme against alkylation yet noncompetitively with respect to iodoacetate. Imidazole and o-phenanthroline compete with one another for binding to the protein molecule of rape ADH. Whereas o-phenanthroline decreases the inactivation rate imidazole increases the rate of iodoacetate inactivation.