The conversion of L-cystathionine into the cyclic ketimine form by heated rat liver extracts containing cystathionase and transaminase activities
Cavallini, D.; Costa, M.; Pensa, B.; Coccia, R.
Biochemistry International 10(4): 641-646
1985
ISSN/ISBN: 0158-5231 PMID: 4026871 Document Number: 256993
Rat liver homogenates heated for 10 min at 60 degrees 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 have been also 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 first report indicating the occurrence in a mammalian tissue of an enzymatic system using cystathionine for reactions differing from the traditional transulfuration to cysteine.