Candida utilis NAD + kinase: Kinetic and inhibition studies with ADP

1. 1. Initial velocity and product inhibition studies using ADP were carried out on cytoplasmic NAD + kinase (ATP:NAD 2′ phosphotransferase, EC 2.7.1.23) purified from Candida utilis. Initial velocity studies were also carried out on a sample of chicken liver NAD +, kinase. 2. 2. The data indicate both enzymes followed a sequential mechanism of reactant binding. 3. 3. Product inhibition studies on C. utilis NAD + kinase suggest the mechanism of NAD +, ATP addition is best described as rapid equilibrium random with multiple binding of ADP to the free enzyme and the E·ATP and E·NAD + complexes. 4. 4. The characteristics of this enzyme, prepared from several sources, are briefly summarized.