Phomopsins comprise a family of peptide mycotoxins containing a 13-membered ring formed by an ether bridge, produced by the fungus Phomopsis leptostromiformis, the causal agent in lupin poisoning (lupinosis). The biochemical actions of two naturally occurring phomopsins, phomopsin A and B, and the chemical derivatives, phomopsinamine A and octahydrophomopsin A, on purified sheep brain tubulin were investigated. All analogues were potent microtubule inhibitors, blocking the polymerization of tubulin at concentrations of less than 1 microM. They inhibited [3H]vinblastine binding to tubulin and, in common with vinblastine and its competitive inhibitor maytansine, enhanced the binding of [3H]colchicine to tubulin. It is postulated that phomopsin A and its analogues exert their action on tubulin by interaction at or near the vinblastine binding site. Two possible mechanisms for the interaction between vinblastine or phomopsins and colchicine binding to tubulin are proposed.

中文翻译：

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磷脂A和相关化合物与纯化的绵羊脑微管蛋白的相互作用

磷视蛋白包含肽霉菌毒素家族，其包含由醚桥形成的13员环，该环由真菌羽扇豆（羽扇豆中毒（羽扇豆病）的病原体）产生。研究了两种天然存在的磷脂酶A和B，以及其化学衍生物磷胺A和八氢磷蛋白酶A对纯化的绵羊脑微管蛋白的生化作用。所有类似物都是有效的微管抑制剂，在小于1 microM的浓度下阻断微管蛋白的聚合。它们抑制[3H]长春碱与微管蛋白的结合，并且与长春碱及其竞争性抑制剂美登素一样，增强了[3H]秋水仙碱与微管蛋白的结合。据推测，视紫红质素A及其类似物通过在长春碱结合位点处或附近的相互作用而对微管蛋白发挥作用。