Crystal and molecular structure of the quinoxaline antibiotic analog TANDEM (des-N-tetramethyltriostin A)

Hossain, MB and Helm, Dick Van der and Olsen, Richard K and Jones, Peter G and Sheldrick, George M and Egert, Ernst and Kennard, Olga and Waring, Michael J and Viswamitra, MA (1982) Crystal and molecular structure of the quinoxaline antibiotic analog TANDEM (des-N-tetramethyltriostin A). In: Journal of the American Chemical Society, 104 (12). pp. 3401-3408.

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Abstract

The crystal structure of TANDEM (des-N-tetramethyltriostin A), a synthetic analogue of the quinoxaline antibiotic triostin A, has been determined independently at -135 and 7 'C and refined to R values of 0.088 and 0.147, respectively. The molecule has approximate 2-fold symmetry, with the quinoxaline chromophores and the disulfide cross-bridge projecting from opposite sides of the peptide ring. The quinoxaline groups are nearly parallel to each other and separated by about 6.5 A. The peptide backbone resembles a distorted antiparallel 13 ribbon joined by intramolecular hydrogen bonds N-H(LVal)--O(L-Ala). At low temperatures, the TANDEM molecule is surrounded by a regular first- and second-order hydration sphere containing 14 independent water molecules. At room temperature, only the first-order hydration shell is maintained. Calculations of the interplanar separation of the quinoxaline groups as a function of their orientation with respect to the peptide ring support the viability of TANDEM to intercalate bifunctionally into DNA.

Item Type:	Journal Article
Publication:	Journal of the American Chemical Society
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences
Date Deposited:	20 Jul 2009 10:01
Last Modified:	19 Sep 2010 05:38
URI:	http://eprints.iisc.ac.in/id/eprint/21587

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