| Popis: |
Summary An enzyme catalyzing the transfer of the p -coumaroyl or caffeoyl moiety of respectively p-coumaroyl-CoA and caffeoyl-CoA to the 4-hydroxyl group of the rhamnosyl moiety of anthocyanidin 3-rhamrnosyl(1 → 6)glucosides and 3-rhamosyl(1 → 6)glucoside-5-glycosides has been demonstrated in petal extracts of Silene dioica plants. This acyltransferase activity is governed by gene Ac ; in petals of aclac plants this activity is 15-times lower than in petals of Ac / Ac plants. The enzyme purified fiftyfold by Dowex 1 × 2 and Sephadex G-150 chromatography, exhibits a p H optimum of 7.6-7.8, has a molecular weight of 56,000 daltons, is not stimulated by divalent metal ions, has a “true Km” value of 3.5μM, for caffeoyl-CoA, of 0.29 mM for cyanidin 3-rhamnosyl(1 → 6)glucoside. p -Coumaroyl-CoA can also serve as substrate donor (“true Kin” 15 pill). For the acceptor pelargonidin 3-rhamnosyl(1 → 0)glucosi(le a “true Kin” of 0.03 mM has been obtained. |
