2,4-Dinitrophenylhydrazone formation at the aldehyde derived by periodate cleavage of α-amanitin

Publisher Website
Google Scholar
Abstract
IO4- cleavage of .alpha.-amanitin after the procedure of Wieland and Fahrmeir but without prior protective methylation of the 6''-hydroxyl of the tryptophan residue affords the .alpha.-amanitin aldehyde in 45% yield. The aldehyde exhibited Ki = 3.0 and 12 .mu.M for Drosophila melanogaster and wheat germ RNA polymerase II [EC 2.7.7.6], respectively. This value is .apprx. 100-fold greater than for the parent .alpha.-amanitin. Treatment of the .alpha.-amanitin aldehyde with 2,4-dinitrophenylhydrazine in CH3OH, CH3CN or dimethylsulfoxide yielded 3 products. Two of these did not contain the 2,4-dinitrophenyl moiety, showed Ki= 3.3 and 0.26 .mu.M for wheat germ RNA polymerase II (.alpha.-amanitin, Ki = 0.09 .mu.M) and accounted for 30-60% and 3% of the input .alpha.-amanitin aldehyde, respectively. The .alpha.-amanitin-2,4 dinitrophenylhydrazone was recovered in < 10% yield regardless of reaction condition and showed a Ki = 0.26 .mu.M on wheat germ RNA polymerase II. This hydrazone establishes that the amatoxin molecule can be modified in the dihydroxyisoleucine residue without disruption of binding to the RNA polymerase.

This publication has 18 references indexed in Scilit: