Oxytocin and neurohypophyseal peptides: spectral assignment and conformational analysis by 220 MHz nuclear magnetic resonance.

Magnetic resonance peaks have been assigned to individual protons of the constituent amino acids in the neurohypophyseal hormone, oxytocin, and in related peptides. The assignments were made possible by operation at 220 MHz with the use of variable temperature studies, proton homonuclear spin-decoupling, and comparison of spectra of oxytocin analogs. Some of the observed chemical shifts, and NH-CH(alpha) coupling constants were studied in relation to the conformation of the hormone.