Role of B-ring of colchicine in its binding to tubulin

Ray, K. ; Bhattacharyya, B. ; Biswas, B. B. (1981) Role of B-ring of colchicine in its binding to tubulin Journal of Biological Chemistry, 256 (12). pp. 6241-6244. ISSN 0021-9258

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The chemical specificity of the colchicine-binding site of tubulin is less stringent for the presence of the B-ring than the A- and C-rings of colchicine, Colchicine analogues with modifications in the B-ring bind to tubulin at the same site as colchicine. Analogues with smaller or no substituents in the B-ring bind tubulin remarkably faster than colchicine. Thus, a compound without the B-ring [2-methoxy-5-(2',3',4'-trimethoxyphenyl)tropone] binds tubulin even at 4 °C and the binding is almost instantaneous at 37 °C. Colcemid and 2-methoxy-5-(2',3',4'-trimethoxyphenyl)tropone bind reversibly to tubulin, whereas colchicine and desacetamidocolchicine bind almost irreversibly, suggesting that the size of the B-ring moiety of colchicine is not related to the reversibility of binding. We conclude that although the presence of the B-ring of colchicine does not appear to be an essential prerequisite for the drug-tubulin interaction, the B-ring substituents play an important role in determining the binding properties of colchicine to tubulin.

Item Type:Article
Source:Copyright of this article belongs to American Society for Biochemistry and Molecular Biology.
ID Code:26152
Deposited On:06 Dec 2010 13:00
Last Modified:17 May 2016 09:29

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