High functionality of novel carbonyl sulfide hydrolase aiming at the effective removal of carbonyl sulfide

羰基硫水解酶（COSase）是从硫氧化细菌中分离得到的一种酶。羰基硫是大气中的一种微量组分，是影响全球气候特别是臭氧消耗的重要气体之一。本研究的目的是获得制备高效酶分子的信息，从而使强力去除COS成为可能。我们通过点突变在酶活性中心和底物或反应产物的通道α 5螺旋附近引入了几个氨基酸的突变，并检测了对COS降解活性的影响。此外，由于土壤环境是大气COS的主要汇，我们尝试从土壤样品中分离新的COS降解微生物。从土壤中分离到了一批新型COS降解微生物，包括细菌和真菌。

Carbonyl sulfide hydrolase (COSase) has been isolated from sulfur oxidizing bacterium. COSase catalyses degradation of carbonyl sulfide (COS) that is a trace constituent in the atmosphere and is considered as one of important gas affecting on the global climate especially on ozone depletion. The aim of our research is to obtain information to make highly efficient enzyme molecule so that powerful removal of COS will be possible. We introduced mutations of several amino acids around the sequence of the active center of the enzyme and alpha 5 helix that is a putative tunnel of substrate or reaction product by forming point mutation and examined the effects against COS degrading activity. Furthermore, we tried to isolate new COS degrading microorganisms from soil samples because soil environment is the major sink of atmospheric COS. Novel COS degrading microorganisms including bacteria and fungi were isolated from the soil.