THE DEVELOPMENT OF A HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ASSAY-METHOD TO DETERMINE PYRUVATE GENERATED DURING THE C-S LYSIS OF CYSTEINE CONJUGATED XENOBIOTICS

It is now well recognized that cysteine conjugates are sometimes responsible for the mutagenic and cytotoxic consequences which occur following the ingestion of halocarbons. These toxic reactions arise from the generation of reactive metabolites via the cleavage of the C-S bond in cysteine conjugates. The enzymes which facilitate this reaction on cysteinyl conjugate metabolites are now known as C-S lyases. The products of the C-S lyase catalysis of cysteine conjugates am a reactive thiol, pyruvic acid and ammonia. Here we report the development of a sensitive fluorimetric hplc assay for pyruvic acid using the derivatising agent 1,2-phenylenediamine. It was found that using this assay CSL activity could be detected in a porcine C-S lyase preparation. It was also observed that this assay was approximately ten-fold more sensitive than the existing spectrophotometric assay,