Purification and characterization of a major esterase BesB from hemolymph of the silkworm Bombyx mori

H. Arai, T. Okido, H. Fujii, H. Doira
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引用次数: 3

Abstract

Total esterase activity in the hemolymph of Bombyx mori was measured using a-naphthyl acetate as a substrate. It was low during the early fifth instar, then sharply increased at the spinning stage and stayed high throughout the pupal stage. One of the major hemolymph esterases of B. mori, previously named BesB (blood esterase B type), was purified from day 1 pupae to homogeneity using procedures such as procainamide hydrochloride affinity chromatography. BesB had an apparent molecular weight of 58,000 and an isoelectric point of 4.6. It was most active at pH 6-7, and was stable around pH 7 to 9. The sequence of N-terminal 28 amino acid residues was partially homologous to previously reported esterases isolated from the peach-potato aphid Myzus persicae. In kinetic parameters, there were no differences in Km values from four tested substrates, but there were differences in Vmax values. BesB had the highest sensitivity to paraoxon and diisopropyl f luorophosphate (DFP), and was moderately affected by eserin sulfate, phenylmethylsulf onyl fluoride (PMSF) and chloromercuribenzoic acid (pCMB). These results indicate that BesB is a carboxylesterase in hemolymph.
家蚕血淋巴主要酯酶BesB的纯化及特性研究
以乙酸萘酯为底物,测定家蚕血淋巴总酯酶活性。在五龄早期较低,在纺丝期急剧上升,在蛹期保持较高水平。一种主要的血淋巴酯酶,以前被命名为BesB(血酯酶B型),从第1天的蛹中使用盐酸普鲁胺亲和层析等方法纯化到均匀性。BesB的表观分子量为58000,等电点为4.6。pH值为6 ~ 7时活性最强,pH值为7 ~ 9时稳定。其n端28个氨基酸残基序列与先前报道的桃蚜酯酶序列部分同源。在动力学参数上,4种基质Km值无差异,但Vmax值有差异。BesB对对氧磷和氟磷酸二异丙基(DFP)的敏感性最高,对硫酸丝素、苯基甲基磺酰氟(PMSF)和氯苯甲苯甲酸(pCMB)的影响中等。这些结果表明BesB是血淋巴中的羧酸酯酶。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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