Synthesis and solution structure of [Val3]-HC toxin by 1H and 13C nuclear magnetic resonance relaxation parameters

Abstract

The [Val³] analogue of the fungal tetrapeptide HC toxin has been synthesised. Conformational parameters of the peptide in solution have been measured by a variety of n.m.r. techniques. The ¹H and ¹³C spectral features were assigned by using two-dimensional n.m.r. methods. Accurate backbone distances (proton–proton and proton–carbon) and those relative to the acceptors and donors of the hydrogen bonds were measured by using homo- and hetero-nuclear Overhauser effects and ¹H and ¹³C relaxation parameters. The peptide conformation thus derived was identical with that of the parental toxin.