J. Biochem, 1988, Vol. 103, No. 6 938-943
© 1988 Japanese Biochemical Society
research-article |
Physiological Role of Glucoside 3-Dehydrogenase and Cytochrome c531 in the Sugar Oxidizing System of Flavobacterium saccharophilum
Department of Biological Chemistry, School of Pharmacy, Hokuriku University Kanazawa, Ishikawa 920-11
Flavobacterium saccharophilum cytoplasmic membranes contain several cytochromes linked to the respiratory chain. The presence of c-type cytochrome, cytochrome o, and a small amount of a-type cytochrome was proved. Cytochrome c551 was purified to electrophoretic homogeneity by ion-exchange chromatography and gel filtration from a membrane fraction of F. saccharophilum and its properties determined. Cytochrome C551 possessed absorption peaks at 407 nm in the oxidized form, and at 415, 521, 551 nm in the reduced form. The cytochrome c551, had a molecular weight of 15,500 as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Glucoside 3-dehydrogenase of F. saccharophilum reduced the cytochrome c551 with methyl-
-D-glucoside, D-glucose, sucrose, or validoxylamine A. When the purified glucoside 3-dehydrogenase was incubatedwith methyl-
-D-glucoside and purified ferricytochrome c551, methyl-
-D-3-ketoglucoside was formed as indicated by GC-MS analysis. The addition of a substrate to the membrane fraction caused an increase in the rate of oxygen uptake and an abrupt reduction in cytochrome c551. The electron transfer in the 3-keto sugar forming system may be as follows: sugars
glucoside 3-dehydrogenase
cytochrome c551
cytochrome oxidase
02. Thus, the electron acceptor of glucoside 3-dehydrogenase is possibly connected to the membrane-bound cytochrome system.