Torsion Angles in the Cystine Bridge of Oxytocin in Aqueous Solution. Measurements of Circumjacent Vicinal Couplings between 1H, 13C, and 15N

Alan J. Fischman, David H. Live, Herman R. Wyssbrod, William C. Agosta, David Cowburn

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Abstract

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.

Original languageEnglish (US)
Pages (from-to)2533-2539
Number of pages7
JournalJournal of the American Chemical Society
Volume102
Issue number8
DOIs
Publication statusPublished - Apr 1980
Externally publishedYes

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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