Metal-peptide interactions: enkephalin rigidifications.
Two enkephalin analogues, Tyr-D-Ala-Gly-Phe-NVal-NH2 and Tyr-D-Ala-Gly-Phe-NVal-OH were studied by n.m.r. spectroscopy. 13C chemical shifts were determined as a function of pH and in water-dimethyl sulfoxide solvent mixtures. The acid and amide forms of the analogues show a marked difference in their n.m.r. features. Complexation with metal ions causes changes in the n.m.r. spectra of the acid form. The temperature dependence of the NH proton resonances of the zinc complex shows striking similarity with that of the amide analogue. The results are discussed in terms of the potential modification of biological activities which may occur following metal ion induced conformation changes.
Calcium↗