Quinoprotein-dependent periplasmic oxidase system in aerobic bacteria

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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.