Bhabatarak Bhattacharyya

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In this review, an attempt has been made to throw light on the mechanism of action of colchicine and its different analogs as anti-cancer agents. Colchicine interacts with tubulin and perturbs the assembly dynamics of microtubules. Though its use has been limited because of its toxicity, colchicine can still be used as a lead compound for the generation of(More)
Cleavage of tubulin by subtilisin removes a small (Mr less than 2000) fragment from the C-terminal end of both alpha and beta subunits. The resulting protein is much reduced in negative charge. The cleaved, less acidic protein retains its competence to polymerize in a GTP-dependent and cold-, GDP-, and podophyllotoxin-sensitive manner and assembles into(More)
The fluorescence emission maximum of a polar fluorophore in viscous medium often shows a dependence on excitation wavelength, a phenomenon which is named red edge excitation shift (REES). We have found that the fluorescence spectra of the tubulin tryptophans exhibit a REES of about 7 nm. Also, their steady state fluorescence polarization and mean lifetimes(More)
Limited proteolysis of rat brain tubulin (alpha beta) by subtilisin cleaves a 1-2-kDa fragment from the carboxyl-terminal ends of both the alpha and beta subunits with a corresponding loss in negative charge of the proteins. The beta subunit is split much more rapidly (and exclusively at 5 degrees C), yielding a protein with cleaved beta and intact alpha(More)
The binding of [3H]podophyllotoxin to tubulin, measured by a DEAE-cellulose filter paper method, occurs with an affinity constant of 1.8 X 10(6) M-1 (37 degrees at pH 6.7). Like colchicine, approximately 0.8 mol of podophyllotixin are bound per mol of tubulin dimer, and the reaction is entropy-driven (43 cal deg-1 mol-1). At 37 degrees the association rate(More)
Colchicine, which does not fluoresce in aqueous media and organic solvents, exhibits marked fluorescence on combination with brain tubulin, with a corrected excitation maximum at 362 nm, an emission maximum at 435 nm, and a quantum yield of about 0.03. From fluorescence measurements it was found that rat brain tubulin binds 0.83 moles of colchicine per(More)
This paper analyzes the effects of family decisions and individual decisions on rural-urban migration in India under 2 different rural institutions--family farm and wage labor systems. An analytical framework for explaining family migration decisions reveals that whenever a member of the extended family migrates, he gives up his share in the produce of the(More)
Studies on vinca domain binding drugs were done in great details by a number of workers as it is recognized as a potential target for anticancer drug development. Their structures, properties, mode of action, success and failures as potential anticancer drug have been discussed in short details in this review. Among these drugs rhizoxin and maytansine are(More)
Tubulin possesses two distinct binding sites for vinblastine; one of high affinity (Ka = 6.2 X 106M” ) occupancy of which prevents polymerization of tubulin and a second, lower affinity site (K, = 8 X 104M”) occupancy of which correlates with the aggregating effects of the alkaloid on tubulin [l]. The recent report [2] that maytansine, a new antitumor agent(More)
Curcumin has shown promising therapeutic utilities for many diseases, including cancer; however, its clinical application is severely limited because of its poor stability under physiological conditions. Here we find that curcumin also loses its activity instantaneously in a reducing environment. Curcumin can exist in solution as a tautomeric mixture of(More)