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  • 标题:Long-Range, pH-Dependent Effects on the Carbon-13 Nuclear Magnetic Resonance Spectra of Oxytocin
  • 本地全文:下载
  • 作者:Roxanne Deslauriers ; Roderich Walter ; Ian C. P. Smith
  • 期刊名称:Proceedings of the National Academy of Sciences
  • 印刷版ISSN:0027-8424
  • 电子版ISSN:1091-6490
  • 出版年度:1974
  • 卷号:71
  • 期号:2
  • 页码:265-268
  • DOI:10.1073/pnas.71.2.265
  • 语种:English
  • 出版社:The National Academy of Sciences of the United States of America
  • 摘要:The effects of hydrogen ion concentrations on the carbon-13 nuclear magnetic resonance spectra of oxytocin were investigated. The starting pD of 3.0 was increased stepwise to 8.4. A change of the state of protonation of the N-terminal amino group of oxytocin is accompanied by changes in chemical shifts of carbon-13 nuclei of amino-acid residues located in the 20-membered ring of the hormone. The resonance positions of the acyclic peptide portion, Pro-Leu-Gly-NH2, remain constant. The pD-induced chemical-shift changes of carbons up to five bonds removed from the site of protonation are interpreted in terms of "through-bond" and "through-space" mechanisms. Chemical-shift changes of carbons more than five bonds removed are proposed to have a conformational origin. It is suggested that a change in the charge density of the amino group perturbs the dihedral angle of the --CH2--S--S--CH2-- moiety of oxytocin, which in turn significantly affects the overall conformation of the 20-membered ring of the hormone.
  • 关键词:“through-bond” mechanism ; “through-space” mechanism ; conformation ; peptide hormones
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