X-ray studies on crystalline complexes involving amino acids and peptides. IX. Crystal structure of L-ornithine L-aspartate hemihydrate

Salunke, D. M. ; Vijayan, M. (1983) X-ray studies on crystalline complexes involving amino acids and peptides. IX. Crystal structure of L-ornithine L-aspartate hemihydrate Chemical Biology &Drug Design, 22 (2). pp. 154-160. ISSN 1747-0277

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Official URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1399-...

Related URL: http://dx.doi.org/10.1111/j.1399-3011.1983.tb02080.x

Abstract

l-Ornithine l-aspartate hemihydrate crystallizes in the space group C2 with a = 21.858(2), b = 4.718(1), c = 18.046(2) Å and β = 137.4(1)° . The crystal structure, solved by direct methods, has been refined to an R value of 0.041 for 1270 observed reflections. The conformation of the two amino acid molecules in the structure are somewhat different from those observed in other crystal structures which contain them. The crystal structure is stabilized by ionic interactions accompanied by hydrogen bonds. The unlike molecules aggregate into separate two-fold helices; each helix of one type is surrounded by, and is in hydrogen bonded contact with, four helices of the other type. The arrangement of the molecules in the structure is such that it can be described as consisting of alternating hydrophilic and hydrophobic regions. The hydrophilic regions contain hydrogen bonded loops, each made up of two amino groups and two carboxylate groups. The structure also provides the first example of a head-to-tail sequence involving two types of amino acids.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
Keywords:Aggregation of Amino Acids; Amino Acid Conformation; Head-to-tail Sequence; Hydrogen Bonded Loops; Ornithine Aspartate; Prebiotic Polymerisation; X-ray Crystal Structure
ID Code:52494
Deposited On:04 Aug 2011 07:46
Last Modified:15 Jul 2012 18:19

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