CHEMICAL SYNTHESIS OF DENDROTOXIN-I - REVISION OF THE REPORTED STRUCTURE

Dendrotoxin I (DTX-I) is a 60-residue peptide from the venom of the bl ack mamba snake Dendroaspis polylepis. which binds to neuronal K+ chan nels. The structure reported previously for DTX-I was synthesized for the first time by a solution procedure. The synthetic product was conf irmed to have the correct primary and disulfide structure determined b y peptide mapping, sequence analysis and mass measurements. Comparison of synthetic DTX-I with the natural one by high-performance liquid ch romatography and capillary zone electrophoresis, as well as by sequenc e analysis, revealed that the Asn residue at position 12 in the synthe tic peptide was Asp in the natural product. Synthesis of DTX-I with As p at position 12 gave a peptide identical with the natural product in all aspects. NMR analysis of synthetic [Asn(12)]- and [Asp(12)]-DTX-I also supported our findings that the Asn residue at position 12 in the DTX-I molecule should be revised as Asp. [Asn(12)]- and [Asp(12)]-DTX -I had very similar binding affinities when tested against radiolabele d dendrotoxin binding to rat brain synaptosomal membranes. (C) Munksga ard 1998.