AMINO GROUP FORMATION AND GLUTAMATE SYNTHESIS IN STREPTOCOCCUS BOVIS

Abstract

Burchall , J. J. (University of Illinois, Urbana), R. A. Niederman, and M. J. Wolin . Amino group formation and glutamate synthesis in Streptococcus bovis . J. Bacteriol. 88: 1038–1044. 1964.—Extracts of Streptococcus bovis grown on NH 4 + as a nitrogen source contain a nicotinamide adenine dinucleotide phosphate (NADP)-linked glutamic dehydrogenase and are devoid of alanine dehydrogenase, other amino acid dehydrohygenases, and aspartase. A potential source of reduced nicotinamide adenine dinucleotide phosphate for glutamate synthesis is a NADP and nicotinamide adenine dinucleotide (NAD)-linked glyceraldehyde-3-phosphate dehydrogenase present in the extracts. Experiments with C 14 -labeled glucose and NaHCO 3 indicate that the glutamate carbon skeleton is synthesized by a tricarboxylic acid pathway. The synthesis of the carbon skeleton of glutamate is repressed when glutamate or casein hydrolysate supplement the NH 4 + -containing growth medium. Repression of glutamic dehydrogenase and a NAD-linked isocitric dehydrogenase occurs only when complex nitrogen sources, but not when free amino acids, are added to the growth medium.