差异intersubunit接触triosephosphate异构酶从两个致病锥密切相关。
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Maldonado E, Soriano-Garcia M,莫雷诺,卡布瑞拉N, Garza-Ramos G, de Gomez-Puyou M, Gomez-Puyou, Perez-Montfort R
差异intersubunit接触triosephosphate异构酶从两个致病锥密切相关。
J杂志。1998;283 (1):193 - 203。
- PubMed ID
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9761683 (在PubMed]
- 文摘
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蒂姆的氨基酸序列对齐鲁兹锥体(TcTIM)和锥虫属brucei (TbTIM) 68%的位置标识。两个酶有明显相似的催化性能。与界面交互的代理半胱氨酸抑制TcTIM TbTIM;和那些缺少这种半胱氨酸的商旅(如人类蒂姆)是这些代理基本上或完全不敏感。易感性的TcTIM代理是TbTIM的大约100倍。确定的原因很大的区别,TcTIM的晶体结构是解决1.83一项决议。这两种酶是为非常相似。在TcTIM TbTIM各自半胱氨酸,15日或14日,形式二聚体界面的一部分。在两者中,联系人的半胱氨酸残基的其他亚基几乎是相同的。然而,有两个值得注意的差异; the existence of glutamine 18 in TbTIM instead of glutamic acid in TcTIM at the beginning of helix 1 decreases the contacts between this portion of the protein and helix 3 of the other subunit. In addition, TcTIM has proline at position 24 in the first helix of the TIM barrel; this is absent in the other TIM. Pro24 disrupts the regular helix arrangement, making the pitch of this helix 1.2 A longer than in TbTIM. When Pro24 of TcTIM was substituted for Glu, the sensitivity of TcTIM to sulfhydryl reagents increased about fivefold, possibly as a consequence of an increase in the space between the first portion of helix 1 and helix 3 of the other subunit. Therefore, it may be concluded that the geometry of the latter region is central in the accessibility to agents that perturb the interface Cys. In human TIM this region is more compact.