Stereochemistry of the inactivation of 4-aminobutyrate: 2-oxoglutarate aminotransferase and L-glutamate 1-carboxylase by 4-aminohex-5-ynoic acid enantiomers.

Incubation of rat brain or bacterial 4-aminobutyrate aminotransferase (EC 2.6.1.19) with both (S)-(+)- and (R)-(-)-enantiomers of 4- aminohex -5- ynoic acid results in a time-dependent irreversible loss of enzymatic activity. Rat brain glutamate decarboxylase (EC 4.1.1.15) is inactivated by the (S)-(+)-enantiomer while the bacterial glutamate decarboxylase is inactivated by the (R)-(-)-enantiomer. In addition, we demonstrate that (R)-(-)-4- aminohex -5- ynoic acid is a selective and effective inhibitor of rat brain 4-aminobutyrate aminotransferase in vivo.