NMR studies of the solution conformation of an active tri-peptide and analogues

Abstract NMR spectra of threonyl-valyl-leucine (TVL; 1 ) and a number of derivatives are presented and assigned for CDCl 3 and DMSO solutions, to determine the conformational mobility of the tri-peptide. At 400 MHz the 1 H spectrum of the leucyl side-chain can be completely analysed and the vicinal couplings show that the side-chain is predominantly in a single conformation. Analysis of the other NMR data, using vicinal (CH.CH and NH.CH) couplings, temperature dependence of the NH chemical shifts, and solvent titrations, indicates that there is considerable conformational mobility in DMSO solution, evidence of specific interactions in some compounds in CDCl 3 solution and that the parent peptide in D 2 O solution shows some evidence of a preferred conformation.