THE CONVERSION OF L-CYSTATHIONINE INTO THE CYCLIC KETIMINE FORM BY HEATED RAT-LIVER EXTRACTS CONTAINING CYSTATHIONASE AND TRANSAMINASE ACTIVITIES

  • 1 January 1985
    • journal article
    • research article
    • Vol. 10  (4) , 641-646
Abstract
Rat liver homogenates heated for 10 min at 60.degree. C incubated with L-cystathionine yield cystathionine ketimine which was identified by its typical UV spectrum and by cochromatography with authentic samples on the amino acid analyzer. Alanine and .alpha.-amino butyric acid were detected among the final products. The reaction is due to heat stable .gamma.-cystathionase and transaminases present in the extracts. Cystathionase produces .alpha.-keto butyric acid and pyruvic acid which are then used for the transamination of the remaining cystathionine to yield the ketimine. This is the 1st report indicating the occurrence in a mammalian tissue of an enzymatic system using cystathionine for reactions differing from the traditional transulfuration to cysteine.