Tubulin binding affinities of podophyllotoxin and colchicine analogues.
Tubulin binding affinities of podophyllotoxin and colchicine analogues.
复制标题
鬼臼毒素和秋水仙碱类似物的微管蛋白结合亲和力。
作者：
J. Kelleher
木脂素鬼臼毒素竞争性抑制秋水仙碱与微管蛋白的结合。研究了 12 种鬼臼毒素和 3 种秋水仙碱类似物抑制秋水仙碱与小鼠脑微管蛋白结合的能力，以鉴定对微管蛋白上的秋水仙碱结合位点具有高亲和力的药物。通过DEAE-纤维素滤纸法测定秋水仙碱结合。结果表明，鬼臼毒素与微管蛋白的结合比秋水仙碱更快，且对温度的依赖性更小。所有活性药物类似物都是竞争性抑制剂。研究发现 β-Peltatin 对小鼠脑微管蛋白的亲和力明显高于鬼臼毒素或秋水仙碱。含有亲水取代基的类似物大大降低了微管蛋白的结合活性，鬼臼毒素的立体异构体也是如此。其他结果表明，鬼臼毒素上内酯环的构象对于确定微管蛋白结合活性可能很重要。这些结果与秋水仙碱结合位点位于疏水口袋中的假设一致。建议体外微管蛋白结合测定作为筛选抗肿瘤药物的有用步骤。
The lignan podophyllotoxin competitively inhibits colchicine binding to tubulin. The ability of 12 podophyllotoxin and three colchicine analogues to inhibit colchicine binding to mouse brain tubulin was investigated in order to identify drugs with high affinity for the colchicine binding site on tubulin. Colchicine binding was assayed by the DEAE-cellulose filter paper method. Results indicated that podophyllotoxin binds to tubulin more rapidly and in less temperature-dependent fashion than colchicine. All active drug analogues were competitive inhibitors. β-Peltatin was found to have a significantly greater affinity for mouse brain tubulin than either podophyllotoxin or colchicine. Analogues containing hydrophilic substitutions had greatly reduced tubulin binding activity, as did stereoisomers of podophyllotoxin. Other results suggest that the conformation about the lactone ring on podophyllotoxin may be of importance in determining tubulin binding activity. These results are consistent with the hypothesis that the colchicine binding site is located in a hydrophobic pocket. Tubulin binding assays in vitro are suggested as useful steps in the screening of antitumor agents.