PMID: 8706862

Authors:

Palm GJ, Lubkowski J, Derst C, Schleper S, Rohm KH, Wlodawer A

Title:

A covalently bound catalytic intermediate in Escherichia coli asparaginase: crystal structure of a Thr-89-Val mutant.

Journal:

FEBS Lett. 1996 Jul 22;390(2):211-6.

Abstract:

Escherichia coli asparaginase II catalyzes the hydrolysis of L-asparagine to L-aspartate via a threonine-bound acyl-enzyme intermediate. A nearly inactive mutant in which one of the active site threonines, Thr-89, was replaced by valine was constructed, expressed, and crystallized. Its structure, solved at 2.2 A resolution, shows high overall similarity to the wild-type enzyme, but an aspartyl moiety is covalently bound to Thr-12, resembling a reaction intermediate. Kinetic analysis confirms the deacylation deficiency, which is also explained on a structural basis. The previously identified oxyanion hole is described in more detail.