外源生长因子对甲烷单加氧酶活性和稳定性的影响

Effects of Exogenous Growth Factors on MMO Activity and Stability

研究结果表明，外源生长因子（维生素Ｂ１２、ｄ－生物素、５－磷酸－吡哆醛、叶酸、原黄素、核黄素）的加入可以使Ｍｅｔｈｙｌｏｓｉｎｕｓｔｒｉｃｈｏｓｐｏｒｉｕｍ３０１１菌的生长量增加．但添加生物素、吡哆醛和叶酸抑制甲烷单加氧酶和可溶性甲烷单加氧酶酶活性，而维生素Ｂ１２、核黄素和原黄素则明显促进甲烷单加氧酶和可溶性甲烷单加氧酶酶活性，可使甲烷单加氧酶和可溶性甲烷单加氧酶酶活性分别提高４０％左右和１５％－４０％，同时甲烷单加氧酶操作稳定性和贮存稳定性也明显提高１－２倍．

Soluble MMO and particulate MMO are two different enzymes which have the same function They coexist in certain methanotrophic strains sMMO can insert oxygen into alkanes,haloalkanes,alkenes,ethers,as well as alicyclic,aromatic and heterocyclic compounds However,pMMO has a significantly narrow substrate range It is very important to improve sMMO activity and stability for the applications of methanotrophs Our results have shown that the addition of growth factors increased the growth yields of methylosinus trichosproum IMV 3011 and sMMO activity during growth and maintenance over extended periods The addition of various growth factors( d biotin,5 phosphate pyridoxal,folic acid,vitamin B 12 ,riboflavin and proflavin)enhanced the growth yields of Methylosinus trichosproum 3011 Addition of d biotin,pyridoxal phosphate and folic acid decreased MMO and sMMO activity,but addition of vitamin B 12 ,riboflavin and proflavin increased MMO and sMMO activity The activity levels of MMO and sMMO at the actively growing stage increased 40% and 15-40%respectively The operational stability of MMO was increased by 1 5 and 2 folds due to the presence of vitamin B 12 and riboflavin Addition of vitamin B 12 and riboflavin also enhanced the storage stability of MMO After storage for 9 days at 16℃,MMO activity of the resting cells still remained 25%-35% of the initial enzymatic activity