title: Initial catabolism of sorbitol in Actinomyces naeslundii and Actinomyces viscosus.
abstract: The initial steps of sorbitol catabolism were studied in 4 strains of Actinomyces naeslundii and Actinomyces viscosus that had been isolated from human dental plaque. Cell-free extracts were prepared from cells grown in the presence of either sorbitol, xylitol or glucose. The extracts from all strains grown on sorbitol had nicotinamide adenine dinucleotide-linked dehydrogenase activities for sorbitol and xylitol and reduced nicotinamide adenine dinucleotide-linked reductase activities for fructose and xylulose. Two of the strains also exhibited these activities when grown in the presence of xylitol, and all glucose-grown cells lacked them. The results indicate that sorbitol metabolism in oral actinomyces involve oxidation of sorbitol to fructose by an inducible enzyme, nicotinamide adenine dinucleotide-linked sorbitol dehydrogenase. This step is followed by the phosphorylation of fructose with guanosine triphosphate as a main phosphoryl donor. Thus, the initial catabolic pathway of sorbitol in A. naeslundii and A. viscosus is different from those described for other oral bacteria.
authors.affiliation: Department of Oral Microbiology, Centre for Oral Health Sciences, University of Lund, Malmö, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Kalfas
authors.forename: N
authors.initials: N
authors.lastname: Takahashi
authors.forename: T
authors.initials: T
authors.lastname: Yamada
mesh_terms: D000190:Actinomyces / Q000378:metabolism*; D016924:Actinomyces viscosus / Q000378:metabolism; D004790:Enzyme Induction; D005636:Fructosephosphates / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D007064:L-Iditol 2-Dehydrogenase / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D013012:Sorbitol / Q000378:metabolism*
chemical_list: D005636:Fructosephosphates; D009243:NAD; D013012:Sorbitol; C027618:fructose-6-phosphate; D010088:Oxidoreductases; D007064:L-Iditol 2-Dehydrogenase; D009247:NADH, NADPH Oxidoreductases; D006593:Hexokinase