Wilson I B, Silman I
Biochemistry. 1977 Jun 14;16(12):2701-8. doi: 10.1021/bi00631a018.
Arsenite inhibits acetylcholinesterase in a second-order reaction. The rate and equilibrium constants depend upon pH and have values on the order of 10(2) M-1 min-1 and 10(5) M (dissociation), respectively. Some quaternary ammonium ligands completely block the arsenite inhibition of the enzyme, others decrease the rate of the reaction and some, notably pyridine-2 aldoxime methiodide, greatly accelerate the rate of the reaction, up to 220-fold. Accelerators may bind at a separate enzyme site distinct form the anionic site involved in substrate binding. Although the kinetic data are consistent with a covalent reaction between arsenite and acetylcholinesterase, chemical evidence excludes the involvement of sulfhydryl groups which are usually implicated in arsenite inhibition.
亚砷酸盐在二级反应中抑制乙酰胆碱酯酶。速率常数和平衡常数取决于pH值，其值分别约为10² M⁻¹ min⁻¹和10⁵ M（解离）。一些季铵配体完全阻断亚砷酸盐对该酶的抑制作用，另一些则降低反应速率，还有一些，尤其是吡啶-2-醛肟甲碘化物，能极大地加速反应速率，高达220倍。加速剂可能结合在与底物结合所涉及的阴离子位点不同的另一个酶位点上。尽管动力学数据与亚砷酸盐和乙酰胆碱酯酶之间的共价反应一致，但化学证据排除了通常与亚砷酸盐抑制作用有关的巯基的参与。
