Effect of TPIs on tubulin polymerization kinetics.

(A) The assembly of MTs was monitored by turbidimetry at 37°C after initiating the polymerization of 10 μM tubulin by 20 μM paclitaxel alone (solid line) or in the presence of wTPI at a concentration of 0.53 μM (dotted line) or 2.12 μM (dashed line). (B) The dependence of the tubulin polymerization rate on TPI concentration is shown for mTPI (○) and wTPI (●), respectively. Data points represent the maximal slope of the turbidity traces shown in panel A, relative to the control (10 μM tubulin alone).