Two crystal structures of (1(3-mercaptopropionic acid) deamino-oxytocin are reported. The ‘dry form’ in space group C 2 has cell dimensions a = 27.08 + 0.03, b = 9.06 + 0.01, c = 22.98 + 0.02 Å, /? = 102.06 + 0.03 with one deamino-oxytocin and six water molecules per asymmetric unit. The ‘wet form’ in space group has cell dimensions a = 27.27 + 0.02, b = 9.04 + 0.01, c = 23.04 + 0.02 Å, B = 102.24 + 0.02, with two deamino-oxytocin and 13 water molecules per asymmetric unit. A local twofold parallel to the monoclinic axis gives a pseudo C 2 packing. Initial phases of the ‘dry form ’ were calculated by the heavy-atom method from the isomorphous and anomalous difference Pattersons and anomalous difference Fourier synthesis. The structure was refined by using restrained least-squares at 1.2 Å resolution to a crystallographic R = 0.10. The molecular replacement method yielded the P 2 1 structure that was refined with geometric restraints to R 0.09, by using all data to 1.09 A resolution. Deamino-oxytocin consists of a cyclic tocin ring formed by six amino acids, closed by a disulphide bridge, S1— S6, and held by two trans-annular hydrogen bonds N2— O5 and N5— O2 with a type II turn at residues 3 and 4. A flexible tripeptide tail has a loosely hydrogen-bonded type I beta-turn between N9 and O6. The sulphur of cysteine at position 1 is disordered in all the molecules leading to alternative hands of disulphide. The conformational flexibility of Ile 3, Asn 5, Pro 7 side chains and the disulphide bridge is consistent with previous models of oxytocin in which flexibility is necessary for biological activity.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTX-ray studies of aspartic proteinase-statine inhibitor complexesJ. B. Cooper, S. I. Foundling, T. L. Blundell, J. Boger, R. A. Jupp, and J. KayCite this: Biochemistry 1989, 28, 21, 8596–8603Publication Date (Print):October 17, 1989Publication History Published online1 May 2002Published inissue 17 October 1989https://doi.org/10.1021/bi00447a049RIGHTS & PERMISSIONSArticle Views109Altmetric-Citations47LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (875 KB) Get e-Alerts Get e-Alerts
Abstract Insulin is a member of a family of hormones, growth factors and neuropeptides which are found in both vertebrates and invertebrates. A common ‘insulin fold’ is probably adopted by all family members. Although the specificities of receptor binding are different, there is possibility of co‐evolution of polypeptides and their receptors.
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