electronic reprint ISSN: 1399-0047 journals.iucr.org/d Bond distances in polypeptide backbones depend on the local conformation Roberto Improta, Luigi Vitagliano and Luciana Esposito Acta Cryst. (2015). D71, 1272–1283 IUCr Journals CRYSTALLOGRAPHY JOURNALS ONLINE Copyright c  International Union of Crystallography Author(s) of this paper may load this reprint on their own web site or institutional repository provided that this cover page is retained. Republication of this article or its storage in electronic databases other than as speciﬁed above is not permitted without prior permission in writing from the IUCr. For further information see http://journals.iucr.org/services/authorrights.html Acta Cryst. (2015). D71, 1272–1283 Improta et al. · Bond distances in polypeptide backbones