Marceau-Day M L, Day D F, Ingram J M
Can J Microbiol. 1978 Apr;24(4):427-32. doi: 10.1139/m78-070.
An alkaline phosphatase mutant of Pseudomonas aeruginosa exhibiting both regulatory and catalytic changes was isolated. Under repression conditions (i.e. high inorganic phosphate (Pi)) the mutant culture produced an alkaline phosphatase (APase) displaying significant activity against both beta-glycerol phosphate (betaGP) and p-nitrophenyl phosphate (pNPP), while the wild type displayed no activity directed towards these substrates under the same conditions. In vivo, the mutant enzyme's ratio of specific activities was 45:1 in favour of betaGP versus pNPP, whereas this ratio was reversed to 1:9 betaGP versus pNPP for the same enzyme isolated from mutant cells. In addition, the kinetic parameters and stability requirements for the mutant-derived enzyme was altered in comparison with those of the wild type. A study of lipopolysaccharide (LPS) preparations from both the mutant and wild type indicated the mutant to be deficient in the core region of its LPS. The authors propose that the modifications in the catalytic activity of the mutant enzyme, demonstrated in vivo, are due to a change in the enzyme's microenvironment.
分离出了一株铜绿假单胞菌的碱性磷酸酶突变体，该突变体在调节和催化方面均有变化。在阻遏条件下（即高无机磷酸盐（Pi）），突变体培养物产生的碱性磷酸酶（APase）对β-甘油磷酸（βGP）和对硝基苯磷酸（pNPP）均表现出显著活性，而野生型在相同条件下对这些底物无活性。在体内，突变酶对βGP与pNPP的比活性为45:1，而从突变细胞中分离出的相同酶对βGP与pNPP的这一比例则相反，为1:9。此外，与野生型相比，突变体衍生酶的动力学参数和稳定性要求发生了改变。对突变体和野生型的脂多糖（LPS）制剂的研究表明，突变体的LPS核心区域存在缺陷。作者提出，体内证明的突变酶催化活性的改变是由于酶微环境的变化所致。
