Ordentlich A, Kronman C, Barak D, Stein D, Ariel N, Marcus D, Velan B, Shafferman A
Department of Biochemistry, Israel Institute for Biological Research, Ness-Ziona.
FEBS Lett. 1993 Nov 15;334(2):215-20. doi: 10.1016/0014-5793(93)81714-b.
Recombinant human acetylcholinesterase (HuAChE) and selected mutants (E202Q, Y337A, E450A) were studied with respect to catalytic activity towards charged and noncharged substrates, phosphylation with organophosphorus (OP) inhibitors and subsequent aging of the OP-conjugates. Amino acid E450, unlike residues E202 and Y337, is not within interaction distance from the active center. Yet, the bimolecular rates of catalysis and phosphylation are 30-100 fold lower for both E450A and E202Q compared to Y337A or the wild type and in both mutants the resulting OP-conjugates show striking resistance to aging. It is proposed that a hydrogen bond network, that maintains the functional architecture of the active center, involving water molecules and residues E202 and E450, is responsible for the observed behaviour.
对重组人乙酰胆碱酯酶（HuAChE）及其选定的突变体（E202Q、Y337A、E450A）进行了研究，内容涉及它们对带电荷和不带电荷底物的催化活性、与有机磷（OP）抑制剂的磷酸化作用以及随后OP缀合物的老化过程。与残基E202和Y337不同，氨基酸E450不在与活性中心的相互作用距离内。然而，与Y337A或野生型相比，E450A和E202Q的双分子催化速率和磷酸化速率都低30至100倍，并且在这两种突变体中，产生的OP缀合物都表现出对老化的显著抗性。有人提出，一个涉及水分子以及残基E202和E450的氢键网络维持了活性中心的功能结构，这是观察到的行为的原因。
