人类butyrylcholinesterase di-isopropyl-phosphorylated的老化。

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马森P,福捷PL, Albaret C, Froment MT,巴特尔CF, Lockridge O

人类butyrylcholinesterase di-isopropyl-phosphorylated的老化。

j . 1997 10月15日,327 (Pt 2): 601 - 7。

PubMed ID

9359435 (在PubMed

]

文摘

Organophosphate-inhibited胆碱酯酶可以通过亲核的激活化合物。有时phosphylated(磷酸化或phosphonylated)胆碱酯酶复活逐步成为耐火材料;这可以从不同的反应结果。最常见的过程,称为“老化”,包括一个烷氧基组织的脱烷基化作用phosphyl一部分通过碳正离子机理。在试图确定的氨基酸残基参与老化butyrylcholinesterase(大餐),人类大餐基因突变在几个位置对应于残留位于活性部位的边缘附近的峡谷和活跃的站点。突变体酶表达中国仓鼠卵巢细胞。野生型大餐和突变体被di-isopropylfluorophosphate pH值8.0和25度c Di-isopropyl-phosphorylated酶是孵化与亲核肟2-pyridine醛肟methiodide及其reactivatability决心。Reactivatability所表达的是衰老的一阶速率常数和/或老化的半衰期(病人)。订单的病人被发现的野生型大餐60分钟。突变glu - 197增加了病人60倍。 Mutation W82A increased t12 13-fold. Mutation D70G increased t12 8-fold. Mutations in the vicinity of the active site serine residue had either moderate or no effect on aging; t12 was doubled for F329C and F329A, increased only 4-fold for the double mutant A328G+F329S, and no change was observed for the A328G mutant, indicating that the isopropoxy chain to be dealkylated does not directly interact with Ala-328 and Phe-329. These results were interpreted by molecular modelling of di-isopropylphosphorylated wild-type and mutant enzymes. Molecular dynamics simulations indicated that the isopropyl chain that is lost interacted with Trp-82, suggesting that Trp-82 has a role in stabilizing the carbonium ion that is released in the dealkylation step. This study emphasized the important role of the Glu-197 carboxylate in stabilizing the developing carbocation, and the allosteric control of the dealkylation reaction by Asp-70. Indeed, although Asp-70 does not interact with the phosphoryl moiety, mutation D70G affects the rate of aging. This indirect control was interpreted in terms of change in the conformational state of Trp-82 owing to internal motions of the Omega loop (Cys-65-Cys-92) in the mutant enzyme.

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药物酶

药物	酶	类	生物	药理作用	行动
Isoflurophate	胆碱酯酶	蛋白质	人类	未知的	抑制剂	细节