Theoretical studies on Beta-lactam antibiotics VI: Conformational analysis and structure-activity relationships of penicillin sulfoxides and cephalosporins

Joshi, NV and Rao, VSR (1982) Theoretical studies on Beta-lactam antibiotics VI: Conformational analysis and structure-activity relationships of penicillin sulfoxides and cephalosporins. In: Journal of Biosciences, 4 (2). pp. 209-218.

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Abstract

Conformational energy calculations were carried out on penicillin α-and Β-sulfoxides and δ2- and δ3-cephalosporins, in order to identify the structural features governing their biological activity. Results on penicillin Β-sulfoxide indicated that in its favoured conformation, the orientation of the aminoacyl group was different from the one required for biological activity. Penicillin α sulfoxide, like penicillin sulfide, favoured two conformations of nearly equal energies, but separated by a much higher energy barrier. The reduced activity of the sulfoxides despite the nonplanarity of their lactam peptide indicated that the orientations of the aminoacyl and carboxyl groups might also govern biological activity. δ3-cephalosporins favoured two conformations of nearly equal energies, whereas δ2-cephalosporins favoured only one conformation. The lactam peptide was moderately nonplanÄr in the former, but nearly planar in the latter. The differences in the.preferred orientations of the carboxyl group between penicillins and cephalosporins were correlated with the resistance of cephalosporins to penicillinases.

Item Type:	Journal Article
Publication:	Journal of Biosciences
Publisher:	Springer India, in co-publication with Indian Academy of Sciences
Additional Information:	Copyright of this article belongs to Springer.
Keywords:	Cephalosporins - penicillin sulfoxides - conformational analysis - structure activity relations
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	29 Dec 2009 07:03
Last Modified:	19 Sep 2010 05:43
URI:	http://eprints.iisc.ac.in/id/eprint/22892

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