SYNTHESIS OF DISULFIDE-BRIDGED FRAGMENTS OF OMEGA-CONOTOXINS GVIA ANDMVIIA - USE OF NPYS AS A PROTECTING ACTIVATING GROUP FOR CYSTEINE IN FMOC SYNTHESES

The 3-nitro-2-pyridinesurphenyl (Npys) moiety is finding increasing ut ility as a protecting-activating group for cysteine, particularly in t he synthesis of cyclic and unsymmetrical disulfides using the Boc stra tegy. This chemistry has been extended to peptides assembled by the Fm oc strategy. N-Terminal Cys(Npys) is introduced via Boc-Cys(Npys)-OPfp , Non-N-terminal Cys(Npys) is incorporated by reacting a resin-bound, fully protected Cys(Acm) peptide with NpysCl. This approach has been a pplied to the synthesis of four disulfide-bridged fragments of w-conot oxins GVIA and MVIIA. (C) Munksgaard 1994.