Oxytocin biologic activity

R. J. Turner, J. M. Matsoukas, and G. J. Moore, Tyrosinate fluorescence lifetimes for oxytocin and vasopressin in receptor-simulating environments Relationship to biological activity and H-NMR data, Biochem. Biophys. Res. Commun. 171, 996-1001 (1990). 

The deamino-dicarba-analogues of various biologically active cystine-containing peptides, such as oxytocin/1-3 calcitonin/31 32 and somatostatin/33-35 have shown high biological activity and enhanced metabolic and chemical stability owing to the absence of reducible disulfide linkages. 

Fortunately, nature has provided a very useful cysteine derivative, D-penicillamine ( 3, 3-dimethylcysteine), which is readily available and inexpensive (the L-isomer is also available, but is much more expensive). The usefulness of this amino acid in biologically active peptide analogues was shown by Schulz and du Vigneaud1 141 who incorporated it into oxytocin and... 

Also, prolylendopeptidase inhibitory peptides (PEP) have been found in wines (Yanai et al. 2003). PEP may have a role in the degradation of biologically active peptides containing proline, such as oxytocin, vasopressin, substance P, bradykinin, neurotensins and angiotensins. Two inhibitory peptides have been isolated and characterized, Pep A (Val-Glu-Ile-Pro-Glu) and Pep B (Tyr, Pro, He, Pro, Phe). Both of them showed PEP inhibition, thereby suppressing the degradation of neuropeptides, vasopressin, substance P and fragments 8-13 of neurotensin, which are involved in memory and neural communication. 

Vignozzi L, Vannelli GB, Morelli A, Mancina R, Marini M, Ferruzzi P, et ai. Identification, characterization and biological activity of oxytocin receptor in the developing human penis. Mol Hum Reprod 2005 [Epub ahead of print]. 

After duVigneaud s proof of the biologically active structure of oxytocin by total synthesis... 

Table 2.14 Biological Activities of Oxytocin (OT) and Selected Agonist Analogs...

Advantages of the solid-phase method are amenability to automation, the almost 100% yield of product for each reaction, the ease of removal of excess reagents and waste products by washing and filtration of resin particles, the lack of need for purification of intermediates, and speed. Peptides or proteins that have been synthesized by the solid-phase method include ribonuclease, bradykinin, oxytocin, vasopressin, somatostatin, insulin, and the S-chain of hemoglobin. The sequence analyses for these substances were confirmed by demonstrating that the synthetic products, constructed on the basis of sequence data, had the same biological activities as those of the corresponding natural substances. 

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