Biphasic kinetics of the colchicine-tubulin interaction: role of amino acids surrounding the A ring of bound colchicine molecule.

ABSTRACT: Isotypes of vertebrate tubulin have variable amino acid sequences, which are clustered at their C-terminal ends. Isotypes bind colchicine at different on-rates and affinity constants. The kinetics of colchicine binding to purified (unfractionated) brain tubulin have been reported to be biphasic under pseudo-first-order conditions. Experiments with individual isotypes established that the presence of beta(III) in the purified tubulin is responsible for the biphasic kinetics. Because the isotypes mainly differ at the C termini, the colchicine-binding kinetics of unfractionated tubulin and the beta(III) isotype, cleaved at the C termini, have been tested under pseudo-first-order conditions. Removal of the C termini made no difference to the nature of the kinetics. Sequence alignment of differ

SUBMITTER: Gupta S 

PROVIDER: S-EPMC4275128 | biostudies-literature | 2005 Aug

REPOSITORIES: biostudies-literature