Prasad, BV Venkataram and Shamala, N and Nagaraj, R and Chandrasekaran, R and Balaram, P (1979) The crystal and molecular structure of benzyloxycarbonyl-a-amino-isobutyryl-L-prolyl-methylamide. The observation of an X2-Pro3 Type III b-turn. In: Biopolymers, 18 (7). 1635 -1646.
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The crystal and molecular structure of N-benzyloxycarbonyl-a-aminoisobutyryl-L-prolyl methylamide, the amino terminal dipeptide fragment of alamethicin, has been determined using direct methods. The compound crystallizes in the orthorhombic system with the space group P212-21. Cell dimensions are a = 7.705 A, b = 11.365 A, and c = 21.904 A. The structure has been refined using conventional procedures to a final R factor of 0.054. The molecular structure possesses a 4 - 1 intramolecular N-H--0 hydrogen bond formed between the CO group of the urethane moiety and the NH group of the methylamide function. The peptide backbone adopts the type 111 P-turn conformation, with 42 = -51.0°, +* = -39.7",&j = -65.0', $3 = -25.4'. An unusual feature is the occurrence of the proline residue at position 3 of the P-turn. The observed structure supports the view that Aib residues initiate the formation of type 111 @-turn conformations. The pyrrolidine ring is puckered in Cy-exo fashion.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to John Wiley and Sons.|
|Department/Centre:||Division of Biological Sciences > Molecular Biophysics Unit|
|Date Deposited:||22 Feb 2010 10:00|
|Last Modified:||19 Sep 2010 05:55|
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