| Autor: |
Bai, Ruoli, Pei, Xue-Feng, Boyé, Olivier, Getahun, Zelleka, Grover, Surinder, Bekisz, Joseph, Nguyen, Nga Y., Brossi, Arnold, Hamel, Ernest |
| Zdroj: |
Journal of Biological Chemistry; May 1996, Vol. 271 Issue: 21 p12639-12645, 7p |
| Abstrakt: |
The colchicine analog 3-chloroacetyl-3-demethylthiocolchicine (3CTC) is a competitive inhibitor of colchicine binding to tubulin, binds to tubulin at 37°C, but not at 0°C, and covalently reacts with β-tubulin at 37°C, but not at 0°C, in a reaction inhibited by colchicine site drugs. The approximate intramolecular distance between the oxygen at position C-3 in 3CTC and the chlorine atom of the 3-chloroacetyl group is 3 Å. Using decylagarose chromatography, we purified β-tubulin that had reacted with 3-(chloromethyl-[14C]carbonyl)-3-demethylthiocolchicine ([14C]3CTC). This β-tubulin was digested with formic acid, cyanogen bromide, endoproteinase Glu-C, or endoproteinase Lys-C, and the radiolabeled peptide(s) were isolated. The sequences of these peptides indicated that as much as 90% of the covalent reaction between the [14C]3CTC and β-tubulin occurred at cysteine 354. This finding indicates that the C-3 oxygen atom of colchicinoids is within 3 Å of the sulfur atom of the Cys-354 residue, suggests that the colchicine A ring lies between Cys-354 and Cys-239, based on the known 9 Å distance between these residues, and may indicate that the tropolone C ring lies between the peptide region containing Cys-239 and the amino-terminal β-tubulin sequence, based on the labeling pattern observed following direct photoactivation of tubulin-bound colchicine. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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