Properties and inhibition of rat malathion carboxylesterases.
Properties and inhibition of rat malathion carboxylesterases.
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大鼠马拉硫磷羧酸酯酶的特性和抑制。
DOI：
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发表时间：
1980
期刊：
影响因子：
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通讯作者：
T. Fukuto
中科院分区：
文献类型：
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作者：
N. M. Mallipudi;R. Talcott;A. Ketterman;T. Fukuto
从大鼠肝微粒体中分离纯化了两个马拉硫磷羧酸酯酶部分，分别命名为酯酶部分A和酯酶部分B，分别纯化了13倍和18倍。这两种酶不能从动力学上区分，但组分A至少含有一个组分B中没有的电泳种。组分A的相对分子质量估计为50,000-60,000；组分B的分子量约为该值的两倍。[甲氧基-14C]马拉硫磷与组分A或组分B孵育产生马拉硫磷α和β单酸混合物，但组分A(α/β=1.5)和组分B(α/β=0.2)产生的混合物的组成不同，表明哺乳动物肝微粒体中存在多种羧酸酯酶。异丙硫磷对大鼠肝脏和大鼠血清马拉硫磷羧酸酯酶的抑制作用明显强于O，S，S-三甲基二硫代磷酸酯。异丙硫磷似乎在抑制大鼠肝脏羧酸酯酶催化的导致α或β-单酸的反应方面是等效的。O、S、S-二硫代磷酸三甲酯则优先抑制了生成α-单酸的反应。反之，异丙硫磷和O，S，S-二硫代磷酸三甲酯对大鼠血清羧酸酯酶催化的α-或β-单元酸反应的抑制程度大致相同。
Two malathion carboxylesterase fractions, designated as esterase fraction A and esterase fraction B, that hydrolyze malathion were purified 13- and 18-fold, respectively, from rat liver microsomes. The two enzymes could not be distinguished kinetically, but fraction A contained at least one electrophoretic species not present in fraction B. The molecular weight of fraction A was estimated as 50,000-60,000; the molecular weight of fraction B was about twice this value. Incubation of [methoxy-14C]malathion with fraction A or fraction B resulted in a mixture of malathion alpha and beta monoacids, but the composition of the mixture produced by fraction A (alpha/beta = 1.5) differed from that produced by fraction B (alpha/beta = 0.2), indicating the presence of multiple species of carboxylesterases in mammalian liver microsomes. Isomalathion was substantially more potent as an inhibitor of both rat liver and rat serum malathion carboxylesterases than O,S,S-trimethyl phosphorodithioate. Isomalathion appeared to be equipotent in inhibiting the rat liver carboxylesterase-catalyzed reactions leading to either alpha or beta-monoacid. O,S,S-Trimethyl phosphorodithioate, on the other hand, preferentially diminished the reactions leading to alpha monoacid. In contrast, the rat serum carboxylesterase-catalyzed reactions leading to either alpha or beta monoacid were inhibited to approximately on equal degree by isomalathion and O,S,S-trimethyl phosphorodithioate.