Olusanya O, Olutiola P O
Department of Medical Microbiology and Parasitology, Faculty of Health Sciences, University of Ife, Nigeria.
Afr J Med Med Sci. 1989 Sep;18(3):163-8.
The quantity of lactase produced by enteropathogenic Escherichia coli (EPEC) was significantly higher (P less than 0.01) than that produced by non-EPEC. The enzyme production was induced by lactose but repressed by glucose and galactose. The lactase from EPEC which was partially purified by ammonium sulphate precipitation and gel permeation chromatography had a molecular weight of 56 kD and apparent Km of approximately 2.78 mM for lactose. The lactase exhibited optimum activity at pH 7.0 at 40 degree C and was stimulated by Mg2+, Mn2+, Na+ and inhibited by Ba2+, Ca+, Cu2+, EDTA, iodo acetic acid (IAA) and Hg2+ and U2+ ions. The higher production of lactase by EPEC may be linked to its pathogenic role in childhood diarrhoea.
肠致病性大肠杆菌（EPEC）产生的乳糖酶量显著高于非EPEC（P小于0.01）。酶的产生由乳糖诱导，但受葡萄糖和半乳糖抑制。通过硫酸铵沉淀和凝胶渗透色谱法部分纯化的EPEC乳糖酶分子量为56 kD，乳糖的表观Km约为2.78 mM。该乳糖酶在40℃、pH 7.0时表现出最佳活性，受Mg2+、Mn2+、Na+刺激，受Ba2+、Ca+、Cu2+、EDTA、碘乙酸（IAA）、Hg2+和U2+离子抑制。EPEC较高的乳糖酶产量可能与其在儿童腹泻中的致病作用有关。
