The six couplings from 1Hα, 13C', and 15N' to the two β protons have been measured for the two half-cystyl residues in oxytocin, using a series of specifically designed and synthesized isotopic isomers. In the case of half-cystyl 1, the observed couplings strongly suggest that the torsion angle x1 (N'-Cα-Cβ-S) has the eclipsed value of 120°. The value for this angle in the half-cystyl residue 6 is less clearly defined, but is probably also fixed. Using the same analysis as for x11, X61 is approximately + 120°. The stereochemical assignments of the ff protons of the two residues have been confirmed by stereoselective deuteration.
ASJC Scopus subject areas
- Colloid and Surface Chemistry