Biochemical and molecular characterization of the homocysteine S-methyltransferase from broccoli (Brassica oleracea var. italica)

Two cDNAs encoding proteins with homocysteine S-methyltransferase (HMT) activity were isolated from broccoli and functionally characterized. While one gene product exhibits only HMT activity, the other displayed both HMT and selenocysteine Se-methyltransferase (SMT) activities, indicating the gene has evolved to include an additional function in sulfur/selenium accumulating species.