Protective Actions of L-Aspartate from Acid or Proteolytic Inactivation

Abstract

(1) L-Aspartate was found to replace L-asparagine in the protective action from acid inactivation of L-asparaginase (EC 3. 5. 1. 1) produced by Escherichia coli A-1-3 and at the same time to inhibit the proteolytic inactivation by α-chymotrypsin.
(2) L-Asparaginase changed in its chromatographic properties in the presence of L-aspartate and became to be absorbed on the CM Sephadex column.
(3) The sedimentation patterns of L-asparaginase at pH 3.5 were identical either in the presence or absence of L-aspartate, showing partial dissociation. But the reversibility to the active state was observed only in the enzyme dissolved in the solution containing L-aspartate.
(4) L-Aspartate did not prevent the enzyme either from the dissociation into subunits or from decrease in the activity by urea.
(5) High concentration of L-aspartate was shown to inhibit the L-asparagine hydrolysis reaction.
(6) L-Aspartate was suggested from ORD measurements to cause changes in the higher structure as well as the ionic properties or proteolytic inactivation.