Carbon-13 nuclear magnetic resonance studies of the binding of selectively 13C-enriched oxytocins to the neurophypophyseal protein, bovine neurophysin II.
Complex formation between bovine neurophysin II and oxytocin molecules containing 85% 13C enrichment in specific amino acid residues was studied using 13C nuclear magnetic resonance spectroscopy. Chemical shift and relaxation time values of the analogue [13C-Leu3]oxytocin, [13C-Gly9]oxytocin, and the doubly labeled [13C-Ile3 Gly9]oxytocin were obtained for the hormones in the absence and presence of neurophysin. The results showed that certain 13C nuclear magnetic resonance parameters of residue 3 but not of residue 9 of oxytocin are altered upon binding to neurophysin. These observations suggest that residue 3 but not residue 9 is involved in the protein-hormone interaction and they demonstrate the general applicability of selective 13C enrichment for the study of peptide-protein interactions.
D000818:Animals; D002247:Carbon Isotopes; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D005998:Glycine; D007532:Isoleucine; D007930:Leucine; D009682:Magnetic Resonance Spectroscopy; D009481:Neurophysins; D010121:Oxytocin / Q000031:analogs & derivatives; D011485:Protein Binding
D002247:Carbon Isotopes; D009481:Neurophysins; D007532:Isoleucine; D010121:Oxytocin; D007930:Leucine; D005998:Glycine