Pyruvate holocarboxylase formation from the apoenzyme and D-biotin in Saccharomyces cerevisiae

Pyruvate apocarboxylase and pyruvate holocarboxylase synthetase, from biotindeficient baker's yeast, have been separated from each other. The formation of holocarboxylase requires these two protein components and also Mg²⁺, ATP, and biotin. Replacement of apoenzyme by hydroxylamine leads to the formation of biotinyl-hydroxamate, which indicates that biotinyl-5′-AMP is an intermediate in the enzymic conversion of apo- to holoenzyme. Acetyl-coenzyme A, which stimulates the activity of the holoenzyme about twofold, has a similar effect, on enzyme formation. l-Aspartate, which inhibits enzyme activity, also inhibits the enzyme formation. Little cross reaction was observed between the pyruvate apocarboxylase-synthetase systems from yeast and from Bacillus stearothermophilus.