Fig. 2.
PAB is a competitive inhibitor of the binding of [3H]colchicine to tubulin. Incubation was for 10 min at 37 °C. Reaction mixtures contained 1.0 μM (0.1 mg/ml) tubulin, which was the last component added to the reaction mixtures. A. Kinetic analysis of binding data. Symbols: no PAB, ○; 10 μM PAB, △; 20 μM PAB, ●; 30 μM PAB; 40 μ M PAB, ▲. Main panel: Lineweaver-Burk plot. The abscissa units are μM−1 colchicine. The ordinate units are 1/pmol colchicine bound. Left inset: Hanes plot. The abscissa units are μM colchicine. The ordinate units are μM colchicine/pmol colchicine bound. Right inset: Woolf plot. The abscissa units are pmol colchicine bound/μM colchicine. The ordinate units are pmol colchicine bound. B. Dixon plot for determination of Ki. Symbols: 2 μM colchicine, △; 3 μM colchicine, ●; 4 μM colchicine, ○; 5 μM colchicine, ◇. The abscissa units are μM PAB. The ordinate units are 1/pmol colchicine bound.
