TY - JOUR T1 - Ant-pro reverse-turn motif. structural features and conformational characteristics JF - European Journal of Organic Chemistry Y1 - 2013 A1 - Thorat, Vijaykumar H. A1 - Ingole, Tukaram S. A1 - Vijayadas, Kuruppanthara N. A1 - Nair, Roshna V. A1 - Kale, Sangram S. A1 - Ramesh, Veera V. E. A1 - Davis, Hilda C. A1 - Prabhakaran, Panchami A1 - Gonnade, Rajesh G. A1 - Gawade, Rupesh L. A1 - Puranik, Vedavati G. A1 - Rajamohanan, Pattuparambil R. A1 - Sanjayan, Gangadhar J. KW - Peptides KW - Peptidomimetics KW - Protein folding KW - Protein structures AB -

This article details the characteristic conformational features of the Ant-Pro reverse turn ? a folded pseudo -turn motif that displays a closed nine-membered-ring hydrogen-bonded network involving just two amino acid residues, namely anthranilic acid (Ant; a constrained -amino acid), and proline (Pro; a constrained -amino acid). The results from the extensive investigation of ten crystal structures and their NMR conformations in the solution state provide a clear idea about the conformational characteristics of the Ant-Pro reverse turn. The Ant and Pro residues, which form the turn segment, maintain a perfect antiperiplanar orientation throughout, leaving little possibility for the formation of the otherwise possible six-membered hydrogen-bonding that requires a coplanar disposition of the two amino acid residues, as clearly evident from investigation of several crystal structures. The closed hydrogen-bonded network observed in the Ant-Pro reverse turn motif, formed in the forward direction of the sequence (12 amino acid interactions) involving only two amino acid residues, is in stark contrast to the native -turns that involve four residues to form hydrogen-bonded network featuring backward 14 amino acid interactions. The readily available two-residue Ant-Pro motif raises the possibility of a practical utility, particularly in the application of rigidifying flexible peptide backbones by inserting the robust Ant-Pro reverse turn motifs into their backbone.

PB - WILEY-V C H VERLAG GMBH CY - BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY IS - 17 U3 - Foreign U4 - 3.154 ER -