Effect of rifampicin on the biological activity of tubulin.

The effect of rifampicin on the biological properties of bovine brain tubulin was investigated. Assembly of microtubules was almost completely blocked by rifampicin, whereas the depolymerization was not affected. The drug was found to inhibit both colchicine and GTP binding to tubulin. Association of rifampicin with tubulin was confirmed by spectrophotometric method. Binding of rifampicin was found to be dependent both on temperature and time. At 0 degrees for 1 hr 0.84 moles of rifampicin were bound per mole of tubulin.