ACYLTRANSFERASES FOR LUPIN ALKALOIDS IN LUPINUS-HIRSUTUS

In the cell-free extracts of 10-day-old seedlings of L. hirsutus, the acyltransferase activities were detected for tigloyl-CoA. 13alpha-hydroxymultiflorine O-tigloyltransferase (HMTase) (EC 2.3.1.-), p-coumaroyl-CoA: epilupinine O-coumaroyltransferase (ECTase) (EC 2.3. 1.-) and feruloyl-CoA: epilupinine O-feruloyltransferase (EFTase) (EC 2.3. 1.-). The HMTase activity was predominantly distributed in hypocotyls and roots of the seedlings. These acyltransferases were partially purified by fractional precipitation with ammonium sulphate and by DEAE-Sepharose chromatography. There was a single HMTase, whose K(m) values were 37 muM for 13alpha-hydroxymultiflorine and 80 muM for tigloyl-CoA. HMTase also showed tigloyl-CoA: 13alpha-hydroxylupanine O-tigloyltransferase (HLTase) (EC 2.3.1.-) activity, although L. hirsutus contains no 13-hydroxylupanine-derived esters. There were two isoenzymes, on the contrary, showing both activities of ECTase and EFTase separated by DEAE-Sepharose chromatography. The activities of HMTase and HLTase were detected in L. hirsutus, L. termis and L. polyphyllus x L. arboreus. However, the activities of ECTase and EFTase were detected only in L. hirsutus.