The thermal properties of porcine brain tubulin polymerization and denaturation and the efftcts of taxol were studied from 4 ℃ to 115 ℃ with a new highly-sensitive differential scanming calorimeter (Micro DSC Ⅲ, Setaram,France). The DSC results indicated that microtubule polymerization can proceed uia an endothermic process and that taxol could alter the process.A large aggregation peak was found at about 85 ℃ in the course of the denaturation and it disap pcared with adding taxol. The heat flow oscillation was observed during the controlled-temperature experiments and taxol could stabilize the structure of the microtubules so that the oscillation disappezred.
The heat properties of porcine brain tubulin polymerization and the interaction of the tubulin with taxol were studied with an MS-80 Calvet Microcalorimeter .The heat vibration occured within 1.5h when tubulin solution was diluted from a highe r concentration to a lower one The thermodynamic parameters of tubulin polymerization at 303- 15K and 298. 15K were measured in 10μmol.L-1 tubulin solution, its H’s were 22kJ·mol-1 and 29.3kJ·mol-1，respectively.Adding different concentration of taxol in the course of polymerization of tubulin give rise to a great change in H. The time of taxol combining to polymerized microtubule was about one minute afer the beginning of the reaction. The mechanism of tubulin polymerization under different conditions was discussed.
