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Leucine Metabolism of Streptococcus Lactis VAR. Maltigenes.¹ II. Transaminase and Decarboxylase Activity of Acetone Powders

Department of Animal Industries, Storrs Agricultural Experiment Station, Storrs, Connecticut

ABSTRACT

Acetone powders of both S. lactis and S. lactis var. maltigenes were shown to possess a transaminase system which effects a transfer of the amino group of leucine to -ketoglutaric acid, resulting in the formation of -ketoisocaproic acid and glutamic acid. This enzyme system is believed to require pyridoxal phosphate as a cofactor and was found to be active at pH 8.4. Although the cell preparations effected the removal of the amino group from leucine at pH 4.6, no concurrent conversion of -ketoglutaric acid to glutamic acid was observed.

Manometric studies demonstrated the presence of a thiaminpyrophosphate-mediated -ketoisocaproic acid decarboxylase in dialyzed acetone powders of S. lactis var. maltigenes, which was absent in similar preparations of S. lactis. The detection of 3-methylbutanal in the reaction mixtures from the manometric experiments confirmed the decarboxylative mechanism.

¹ This paper was prepared from data presented in a thesis by the senior author in partial fulfillment of requirements for the degree of Doctor of Philosophy at the University of Connecticut.

This article has been cited by other articles:

				M. Nemecek-Marshall, C. Wojciechowski, W. P. Wagner, and R. Fall Acetone Formation in the Vibrio Family: a New Pathway for Bacterial Leucine Catabolism J. Bacteriol., December 15, 1999; 181(24): 7493 - 7499. [Abstract] [Full Text]