Reactions of asparaginase II of Saccharomyces cerevisiae. A mechanistic analysis of hydrolysis and hydroxylaminolysis.

Detailed kinetic analysis was performed on asparaginase II, a cell wall glycoprotein from Saccharomyces cerevisiae. The enzyme was highly active in the hydrolysis and hydroxylaminolysis reactions with D- and L-asparagine and with a variety of N-substituted analogues. The data from studies involving pH dependencey, substrate saturation, and product inhibition support the hypotheses that (a) the yeast asparaginase mechanism proceeds via an acyl enzyme intermediate; (b) an ionizable group on the enzyme, pK approximately 6.0, is involved in the acylation and deacylation reactions; and (c) yeast asparaginase II is a peptidoasparaginase.