S-(N-Methylthiocarbamoyl)-d-and l--cysteine (MTCC) are new irreversible inhibitors of the amino acid racemase from Pseudomonas putida. Interactions between d-or l-MTCC and purified amino acid racemase were investigated. The racemase catalyzes not only racemization reactions of d-and l-MTCC but also their αβ, elimination reactions with concomitant inactivation. This inactivation exhibits the characteristics of suicide inhibition, ...