Synthesis of a doubly labelled concanamycin derivative for ATPase binding studies

Abstract

The synthesis of a doubly labelled concanamycin derivative for binding studies with V- and P-type ATPases is described. The starting point was 21-deoxyconcanolide A (6), which was generated from concanamycin A (1) in three steps and which exhibited the full ATPase inhibitor activity, with the advantage of a stability better than that of 1. Through use of a suitable protecting group for 6, the carbene-generating diazirine residue and I-125 were introduced regio- and stereo- selectively. The inhibitory efficacy of the resulting 23-iodo(I-125)-9-O-[p-(trifluoroethyldiazirinyl)benzoyl]-21,23- dideoxyconcanolide A (11b) turned out to be high enough for labelling studies. Photoaffinity labelling experiments clearly showed that 11b is a suitable derivative with which to determine the binding site of concanamycin-like compounds in different ATPases.