Karunaratne S H, Jayawardena K G, Hemingway J, Ketterman A J
Department of Medical Parasitology, London School of Hygiene and Tropical Medicine, U.K.
Biochem J. 1993 Sep 1;294 ( Pt 2)(Pt 2):575-9. doi: 10.1042/bj2940575.
The enzyme, esterase B2, involved in insecticide resistance has been purified and characterized from the mosquito Culex quinquefasciatus. The monomeric enzyme has an M(r) of 62000 and a pI of 5.0. This enzyme is compared with the esterase A2 previously characterized [Ketterman, Jayawardena and Hemingway (1992) Biochem. J. 287, 355-360]. The kinetic constants for interaction with several insecticides indicate, as for the esterase A2, that the B2 enzyme has a role in resistance. The rates and affinities of binding observed support the hypothesis that the role mainly is sequestration followed by the slow turnover of the insecticide. Although the B2 esterase appears to have a slightly higher rate of interaction with insecticides, the A2 has a much greater Vmax. with the xenobiotic substrates studied. The B2 esterase also appears to be present in the larvae to a lesser extent than the esterase A2.
参与抗杀虫剂作用的酯酶B2已从致倦库蚊中纯化并进行了特性鉴定。该单体酶的相对分子质量为62000，等电点为5.0。此酶与先前已鉴定特性的酯酶A2进行了比较[凯特曼、贾亚瓦德纳和海明威（1992年）《生物化学杂志》287卷，355 - 360页]。与几种杀虫剂相互作用的动力学常数表明，和酯酶A2一样，B2酶在抗药性中起作用。所观察到的结合速率和亲和力支持这样的假说，即其作用主要是螯合，随后是杀虫剂的缓慢周转。尽管B2酯酶与杀虫剂的相互作用速率似乎略高，但对于所研究的异生物质底物，A2具有更高的最大反应速度。B2酯酶在幼虫中的含量似乎也比酯酶A2少。
