Determination of free D-amino acids with a bacterial transaminase: their depletion leads to inhibition of bacterial growth.
A general procedure is described to determine the common free D-amino acids except D-proline in mixtures that also contain L-amino acids. The system employs exogenous pure bacterial D-amino acid transaminase coupled with 2-oxohexanoate, which accepts the amino group from D-amino acids to form D-norleucine. This amino acid is readily quantified by amino acid analysis since it elutes in a position not occupied by any of the common amino acids. Formation of norleucine denotes the presence of some D-amino acid(s) whose identity can be established by a corresponding decrease in the susceptible amino acid(s) after treatment. The utility of the procedure is demonstrated by determination of the amounts of free D-alanine and free D-glutamate in extracts of Escherichia coli JM-103 grown on minimal medium; D-alanine was the major D-amino acid. By the same principle, 2-oxohexanoate through coupling with endogenous bacterial D-amino acid transaminase is shown to be capable of inhibiting the growth of E. coli by depleting it of the D-alanine and D-glutamate.
Jones
W M
WM
Rockefeller University, New York, New York.
Ringe
D
D
Soda
K
K
Manning
J M
JM
D000596:Amino Acids / Q000032:analysis* / Q000378:metabolism; D002208:Caproates / Q000494:pharmacology; D051263:D-Alanine Transaminase; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D007700:Kinetics; D009646:Norleucine / Q000378:metabolism; D013223:Statistics as Topic; D013237:Stereoisomerism; D013379:Substrate Specificity; D000637:Transaminases / Q000378:metabolism*
D000596:Amino Acids; D002208:Caproates; D005971:Glutamates; C001916:alpha-ketocaproic acid; D018698:Glutamic Acid; D009646:Norleucine; D000637:Transaminases; D051263:D-Alanine Transaminase