Treatment with propyzamide at 2 × 10-6 M or at higher concentrations arrested the cell cycleat metaphase in tobacco BY-2 cells. Metaphase cells having disorganized spindle microtubulesand scattered chromosomes began to appear within several minutes of the addition of propyzamide. Within 30 min, disrupted spindle microtubules and dispersed chromosomes were seenin all metaphase cells. Propyzamide at 2 × 10-6 M or at higher concentrations also disrupted cortical microtubules, but disruption of cortical microtubules required more time than disruption of spindle microtubules. The effect of propyzamide on microtubules was found to be readily reversible. The cells arrested at metaphase by 2 × 10-6 M propyzamide resumed mitosis within 2 h from the termination of treatment with propyzamide. Spindle microtubules reappeared within 15 min from the termination of treatment with propyzamide, and the cortical microtubules within 1 h. Tubulin was isolated from tobacco BY-2 cells by column chromatography on ethyl Nphenylcarbamate-Sepharose 4B. On incubation with EGTA, Mg2+ and DMSO, the purified tobacco tubulin polymerized into microtubules. Propyzamide at 1 × 10-4 M completely inhibitedthe polymerization of tobacco tubulin, but did not inhibit polymerization of bovine braintubulin. Tobacco tubulin was adsorbed onto a column of propyzamide-analogue-linked Sepharose 4B and then purified by chromatography on this column.
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Akashi et al. (1988) studied this question.