Crystal structure of a tripeptide containing aminocyclododecane carboxylic acid: a supramolecular twisted parallel β‐sheet in crystals |
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Authors: | Prema G. Vasudev Subrayashastri Aravinda Narayanaswamy Shamala |
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Affiliation: | Department of Physics, Indian Institute of Science, Bangalore, India |
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Abstract: | The crystal structure of a tripeptide Boc‐Leu‐Val‐Ac12c‐OMe ( 1 ) is determined, which incorporates a bulky 1‐aminocyclododecane‐1‐carboxylic acid (Ac12c) side chain. The peptide adopts a semi‐extended backbone conformation for Leu and Val residues, while the backbone torsion angles of the Cα,α‐dialkylated residue Ac12c are in the helical region of the Ramachandran map. The molecular packing of 1 revealed a unique supramolecular twisted parallel β‐sheet coiling into a helical architecture in crystals, with the bulky hydrophobic Ac12c side chains projecting outward the helical column. This arrangement resembles the packing of peptide helices in crystal structures. Although short oligopeptides often assemble as parallel or anti‐parallel β‐sheet in crystals, twisted or helical β‐sheet formation has been observed in a few examples of dipeptide crystal structures. Peptide 1 presents the first example of a tripeptide showing twisted β‐sheet assembly in crystals. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. |
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Keywords: | tripeptide crystal structure 1‐aminocyclododecane‐1‐carboxylic acid twisted β ‐sheet |
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