ISSN:
0006-3525
Keywords:
x-ray crystallography
;
ionophore
;
valinomycin analogue
;
crystal and molecular structure
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The crystal and molecular structure of the valinomycin analogue, cyclo [(D-Val-L-Lac-L-Ala-D-Hyi)2 (D-Val-L-Lac-L-Val-D-Hyi)] has been solved by x-ray direct methods using the “Shake and Bake” procedure. The crystals, grown from a mixture of octane/CH2Cl2, belong to space group P21 (Z = 4 ) with cell parameters a = 10.29, b = 32.08, c = 18.73 Å β = 97.05°, and contain two molecules per asymmetric unit. After anisotropic refinement the standard reliability factor was R1 = 0.058. The conformations of both independent molecules is similar to that observed for isoleucinomycin, cyclo [-(D-Ile-L-Lac-L-Ile-D-Hyi)3] [V. Z. Pletnev et al. (1980) Biopolymers, Vol. 19, pp. 1517-1534]. The structure has an asymmetric conformation stabilized by six intramolecular H bonds, five bonds being of the 4 → 1 type and one bond being of the 5 → 1 type. One water molecule is caged in the internal cavity of each cyclodepsipeptide. This conformation could represent an intermediate state between free and complexed forms of valinomycin. © 1997 John Wiley & Sons, Inc. Biopoly 42: 651-658, 1997
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
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