Conformational preferences and binding to neurophysins of oxytocin analogs with sarcosine or N-methylalanine in position 7.
The 600 MHz proton n.m.r. spectra of (sarcosyl7)-oxytocin and (N-methylalanyl7) oxytocin in 2H2O solution have been recorded and completely assigned. In each case the spectrum indicates the presence of two slowly interconverting conformers, which are the cis-trans isomers about the peptide bond between residues six and seven. The trans isomer is energetically favored in both cases. When neurophysin is added to a solution of (N-methylalanyl7) oxytocin or (sacrosyl7)-oxytocin at pH 3.0, the proportion of minor conformer remains constant, indicating that the cis and trans conformers are equally tightly bound to the protein.
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D000409:Alanine / Q000031:analogs & derivatives / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D009481:Neurophysins / Q000378:metabolism*; D010121:Oxytocin / Q000031:analogs & derivatives* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D012521:Sarcosine / Q000032:analysis; D013237:Stereoisomerism
D009481:Neurophysins; D010121:Oxytocin; C008408:N-methylalanine; D000409:Alanine; D012521:Sarcosine