Long A R, Anthony C
Biochemistry Department, University of Southampton, UK.
J Gen Microbiol. 1991 Oct;137(10):2353-60. doi: 10.1099/00221287-137-10-2353.
A modifier protein (M-protein), which increases the affinity of methanol dehydrogenase (MDH) for alcohols but decreases its affinity for formaldehyde, has been partially purified from Methylophilus methylotrophus and Paracoccus denitrificans. Analysis was complicated by non-protein factors in bacterial extracts that are able to mimic M-protein in one of its functions-that of increasing the activity of MDH with butane-1,3-diol in the dye-linked assay system. The 67 kDa polypeptide, previously identified as a subunit of the M-protein, is an unrelated cytoplasmic protein. The M-protein is exclusively periplasmic and is a multimeric protein with subunits of 45 kDa. The M-protein is active in the 'physiological' assay system with the specific cytochrome c electron acceptor for MDH, lowering its affinity for formaldehyde. It has its maximum effect when the ratio of M-protein:MDH is 1:5 but its concentration in the periplasm is much lower than 20% of that of MDH.
一种修饰蛋白（M蛋白）已从嗜甲基甲基ophilus菌和反硝化副球菌中部分纯化出来，该蛋白可提高甲醇脱氢酶（MDH）对醇类的亲和力，但会降低其对甲醛的亲和力。细菌提取物中的非蛋白质因子使分析变得复杂，这些因子能够在染料偶联测定系统中模拟M蛋白的一种功能，即提高MDH对1,3 - 丁二醇的活性。先前被鉴定为M蛋白亚基的67 kDa多肽是一种无关的细胞质蛋白。M蛋白仅存在于周质中，是一种具有45 kDa亚基的多聚体蛋白。在使用MDH的特定细胞色素c电子受体的“生理”测定系统中，M蛋白具有活性，可降低其对甲醛的亲和力。当M蛋白与MDH的比例为1:5时，它具有最大效应，但其在周质中的浓度远低于MDH浓度的20%。
