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.