PURIFICATION AND CHARACTERIZATION OF THREE ISOFORMS OF S-ADENOSYL-L-METHIONINE: (R,S)-TETRAHYDROBENZYLISOQUINOLINE-N-METHYLTRANSFERASE FROM BERBERIS KOETINEANA CELL CULTURES

Article abstract of DOI:10.1016/0031-9422(90)85263-F

Three distinctly different isoforms of S-adenosyl-L-methionine-(R,S)-tetrahydroisoquinoline-N-methyltransferases could be isolated from cell suspension cultures of Berberis koetineana.These isoforms were designated NMT-I, -II and -III.The three enzymes have different molecular weights (60-78 * 10³), pH optima (6.8/7.4), kinetic properties and substrate specificities.NMT-I showed maximal activity with (R)-tetrahydropapaverine as substrate, NMT-II and -III were most active against (R)-coclaurine.The mixture of all three NMT's was immobilized on CH-Sepharose or CPG-10 glass beads.The enzymes under these conditions retained their properties and represent a useful tool for the preparative synthesis of isotopically labelled N-methylated benzylisoquinoline alkaloids.