微生物共轭亚油酸异构酶的生物学研究

BIOLOGICAL RESEARCH ON CONJUGATED LINOLEIC ACID ISOMERASE OF MICROORGANISMS

在各种共轭亚油酸异构体中,c9,t11-18∶2和t10,c12-18∶2这两种天然不饱和脂肪酸异构体被认为具有生物活性,如抗癌、抗动脉粥样硬化、减肥、促进生长、缓和免疫反应副作用等,因而在医药、食品、保健品、化妆品等领域有着广阔的应用前景.一些微生物能产生共轭亚油酸异构酶(Conjugated linoleic acid isomerase,EC 5.2.1.5),该酶又能专一性地催化亚油酸转化为活性共轭亚油酸异构体的反应,因此近几年来倍受关注,利用生物合成法生产共轭亚油酸已成为该领域未来的发展趋势.然而目前,共轭亚油酸异构酶的物种分布及进化关系、在细胞中的生物学功能、结构域、催化反应机理等尚未得到完整的阐释,利用基因工程技术大量高效地表达有活性的重组酶也尚未得到很好的解决.本文在前人对共轭亚油酸异构酶进行的多方面研究的基础上,对近年来共轭亚油酸异构酶的分布、生物学作用、酶的催化反应机理、酶基因的克隆表达等生物学方面的研究进展进行了综述,并利用生物信息学方法对已知的共轭亚油酸异构酶序列进行了初步分析.

Among all of the CLA isomers, c9, t11 - 18：2 and t10, c12 - 18：2 isomers were considered to be the two with many important physiological activities, such as anticarcinogenic activity, antiatherogenic activity, as well as the ability to reduce body - weight, enhance growth promotion and reduce the catabolic effects of immune stimulation, and thus showed a wide field of application in medicine, food, health care and cosmetic industry. Some microorganisms could produce conjugated linoleic acid isomerase （EC 5.2.1.5） , which could catalyze the chemical reaction of linoleic acid （LA） to either or both of the two CLA isomers with the above physiological activities. Therefore, the production of conjugated linoleic acid through biological method was considered to be the developing trend in the future, so conjugated linoleic acid isomerase has been attracting the attention of many researchers in and abroad. However, distribution of this enzyme in species, their evolutionary relationship, its biological function in vivo, active center and catalytic mechanism etc haven＇ t been revealed by now, effective expressing of recombined conjugated linoleic acid isomerase using genetic engineering technique also remains to be a problem. Progress achieved in the field of biological study of conjugated linoleic acid isomeras in recent years, such as distribution of conjugated linoleic acid isomerase, biological function, proposed catalytic mechanism, cloning and expression of the gene were summerized in this paper, primary analysis of the known sequences of the enzyme using bioinformatics method were also put forward.