Ohkuma M, Ohtoko K, Takada N, Hamamoto T, Usami R, Kudo T, Horikoshi K
Microbiology Laboratory, Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
FEMS Microbiol Lett. 1996 Apr 1;137(2-3):247-52. doi: 10.1111/j.1574-6968.1996.tb08113.x.
A metabolic key enzyme malate dehydrogenase (MDH) was purified from a deep-sea psychrophilic bacterium, Vibrio sp. strain no. 5710. The enzyme displayed an optimal activity shifted toward lower temperature and a pronounced heat lability. A gene encoding this enzyme was isolated and cloned. Recombinant Escherichia coli cells harboring the isolated clone expressed MDH activity with temperature stability identical to that of the parental psychrophile. Nucleotide sequencing of the gene revealed that its primary sequence was similar to that of a mesophile E. coli MDH (78% amino acid identity), for which the three-dimensional structure is known. The enzyme is thus suitable for the analysis of molecular adaptations to low temperatures.
一种代谢关键酶——苹果酸脱氢酶（MDH），是从深海嗜冷细菌弧菌属5710菌株中纯化得到的。该酶表现出最佳活性向低温偏移，且热稳定性明显较差。编码这种酶的基因被分离并克隆。携带分离克隆的重组大肠杆菌细胞表达出的MDH活性，其温度稳定性与亲本嗜冷菌相同。该基因的核苷酸测序表明，其一级序列与中温大肠杆菌MDH的序列相似（氨基酸同一性为78%），而中温大肠杆菌MDH的三维结构是已知的。因此，这种酶适用于分析分子对低温的适应性。
