Effects of Acetylation with Acetic Anhydride

Abstract

1) L-Asparaginase (EC 3. 5. 1. 1) from Escherichia coli A-1-3 was acetylated using acetic anhydride as a modifying chemical. The fully acetylated L-asparaginase retained 60% of the activity of the unmodified L-asparaginase.
2) The acetylated L-asparaginase hydrolyzed D-asparagine and L-glutamine as well as L-asparagine in the same ratio as the unmodified L-asparaginase did.
3) However, the effects of pH on the activity of the acetylated L-asparaginase showed very interesting differences from that of L-asparaginase. On the other hand, both L-aspara-ginase and the acetylated L-asparaginase exhibited similar pH activity curves on L-glutamine hydrolysis.
4) The acetylated L-asparaginase was found to become more stable against acid or heat in the presence of L-aspartate than in its absence in the same manner as L-asparaginase was.