Quinoprotein-dependent periplasmic oxidase system in aerobic bacteria

与来自德国和荷兰的三个不同研究所的一年合作取得了以下成果。(1)利用富集技术从土壤中分离到一株恶臭假单胞菌HK5。三种不同的藜蛋白醇脱氢酶在不同的醇上表达。它们是一种喹诺蛋白和两种喹诺血红蛋白，在质周氧化酶的基础上，在生物化学、生理学和应用酶学方面表现出了有趣的方面。(2)葡萄糖脱氢酶是一种典型的藜蛋白，根据其定位分为膜结合酶和可溶性酶两种。这两种酶被高度纯化并转化为载脂蛋白酶。研究了PQQ与载脂蛋白酶的结合过程，揭示了两者在许多方面完全不同。(3)从亚氧丹葡萄杆菌的膜组分中纯化出一种无活性的醇脱氢酶。非常有趣的是，无活性的酶可以通过消耗生物能而转化为活性酶。(4)亚氧化糖葡杆菌醇脱氢酶由三个不同的亚基组成。第二个亚基含有3摩尔细胞色素c，在醇氧化的催化活性中显示出一个有趣的现象。本文首次提出了酶活性过程中分子内电子流动的证据。

One year collaboration with three different institutes from Germany and the Netherlands has yielded the following results.(1) A novel bacterial strain, Pseudomonas putida HK5, was isolated from soil by enrichment technique. Three distinct quinoprotein alcohol dehydrogenases are expressed when grown on different alcohols. They are one quinoprotein and two quinohemoproteins and they showed interesting aspects in biochemistry, physiology and applied enzymology, on the basis of periplasmic oxidase.(2) Glucose dehydrogenase, a typical quinoprotein, is divided into two species depending on their localization, membrane-bound and soluble enzymes. The two enzymes were highly purified and converted to the apo-enzymes. The binding process of PQQ to the apo-enzymes was investigated revealing that the two enzymes are completely different each other in many aspects.(3) An inactive enzyme of alcohol dehydrogenase has been purified from the membrane fraction of Gluconobacter suboxydans. It is interesting very much to know that the inactive enzyme can be converted to the active one by the expenses of biological energy.(4) Alcohol dehydrogenase from Gluconobacter suboxydans is consisted of three different subunits. The second subunit contains three moles of cytochromes c and shows an interesting phenomena during the catalytic activity of alcohol oxidation. Several evidence for intramolecular flow of electron during enzyme activity were presented for the first time.