The role of the B-ring of colchicine in the stability of the colchicine-tubulin complex

Asok Banerjee, Larry D. Barnes, Richard F. Luduena

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

The binding of colchicine to tubulin is a slow, temperature-dependent and a poorly reversible process. Colchicine analogues modified in the B-ring of colchicine have been reported to bind to tubulin fairly rapidly (Ray, K., Bhattacharyya, B. and Biswas, B.B. (1981) J. Biol. Chem. 256, 6241-6244). In an effort to test the role of the B-ring in the reversibility of the colchicine-tubulin binding reaction, we have studied the kinetics of dissociation of the drug-tubulin complex for two B-ring-modified colchicine analogues under conditions in which the association reaction was blocked with a 40-fold excess of podophyllotoxin. In both cases, the dissociation was biphasic. The off-rate constants were determined and the results strongly suggest that the B-ring part of colchicine is responsible for the stability of the drug-tubulin complex. The dissociation data have been explained in terms of a binding model in which the binding of colchicine to tubulin involves a three-subdomain interaction rather than the previously sugges`ted two-subdomain model (Andreu, J.M. and Timasheff, S.N. (1982) Biochemistry 21, 534-543).

Original languageEnglish (US)
Pages (from-to)138-144
Number of pages7
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Volume913
Issue number2
DOIs
StatePublished - Jun 17 1987

Keywords

  • Colchicine B-ring
  • Macromolecular stability
  • Tubulin-colchicine complex

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology

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