Propylamine Transferases in Chinese Cabbage Leaves

Abstract

We have found spermidine synthase and spermine synthase activities in extracts of leaves of Chinese cabbage (Brassica pekinensis var. Pak Choy) and have developed an assay of the former in crude extracts. The method is based on the transfer of the propylamine moiety of decarboxylated S-adenosylmethionine to labeled putrescine, followed by ion-exchange separation of the labeled amine substrate and product, which are then converted to the 5-dimethylamino-1-napthalene sulfonyl (dansyl) derivatives and further purified and identified by thin layer chromatography. The specific radioactivity of putrescine present in the reaction mixture is determined, as is the radioactivity present in dansyl spermidine. The enzyme is also present in extracts of spinach leaves.