Mulbry W
US Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Soil Microbial System Laboratory, Maryland 20705-2350, USA.
Microbiol Res. 2000 Mar;154(4):285-8. doi: 10.1016/S0944-5013(00)80001-4.
We characterized a novel organophosphorus hydrolase (OPH) activity expressed by Nocardiodes simplex NRRL B-24074, a member of a coumaphos-degrading microbial consortium from cattle dip waste. Like the previously characterized OPH from Nocardia sp. strain B- (NRRL B- 16944), OPH activity in N. simplex is located in the cytoplasm and is expressed constitutively. The purified enzyme is monomeric, has a native molecular size of 45,000 Da and has a specific activity toward ethyl parathion of 33 micromole/min x mg protein. Km constants for the enzyme with the structurally related organophosphate pesticides ethyl parathion and EPN were 100 microM and 345 microM, respectively. Although OPH activity in extracts did not require the addition of divalent cations, the purified enzyme lost activity during dialysis against phosphate buffer and this activity could be restored after incubation in buffer containing either CoSO4 or CuSO4. Our results suggest that OPH activity in N. simplex is distinct from other known OPHs and that the responsible gene is unrelated to known genes.
我们对简单诺卡氏菌NRRL B - 24074所表达的一种新型有机磷水解酶（OPH）活性进行了表征，该菌是来自牛浸液废物中降解蝇毒磷的微生物群落的成员。与之前表征的诺卡氏菌属菌株B -（NRRL B - 16944）的OPH一样，简单诺卡氏菌中的OPH活性位于细胞质中且组成型表达。纯化后的酶为单体，天然分子大小为45,000 Da，对乙基对硫磷的比活性为33微摩尔/分钟×毫克蛋白。该酶对结构相关的有机磷农药乙基对硫磷和EPN的Km常数分别为100微摩尔和345微摩尔。虽然提取物中的OPH活性不需要添加二价阳离子，但纯化后的酶在对磷酸盐缓冲液进行透析时会失去活性，并且在含有CoSO4或CuSO4的缓冲液中孵育后该活性可以恢复。我们的结果表明，简单诺卡氏菌中的OPH活性与其他已知的OPH不同，并且相关基因与已知基因无关。
