Effects of Acetylation with Acetic Anhydricle

1. L-Asparaginase (EC 3.5.1.1) from Escherichia coli A–l–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-asparaginase 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.