title: Enzymatic activities affecting exogenous nicotinamide adenine dinucleotide in human skin fibroblasts.
abstract: The fate of nicotinamide adenine dinucleotide (NAD), AMP, and ADP-ribose supplied to intact human skin fibroblasts was monitored, and the concentrations of intra- and extracellular pyridine and purine compounds were determined by HPLC analysis. Two enzymatic activities affecting extracellular NAD were detected on the plasma membrane, one hydrolyzing the pyrophosphoric bond and yielding nicotinamide mononucleotide (nucleotide pyrophosphatase) and the other cleaving the glycoside link and releasing nicotinamide (NAD-glycohydrolase). No AMP or ADP-ribose was found in the extracellular medium of cells incubated with NAD, the former being completely catabolized to hypoxanthine and the latter degraded to adenine and hypoxanthine.
authors.affiliation: Department of Biomedical Sciences and Biotechnology, University of Brescia, Italy.
authors.forename: M F
authors.initials: MF
authors.lastname: Aleo
authors.forename: S
authors.initials: S
authors.lastname: Sestini
authors.forename: G
authors.initials: G
authors.lastname: Pompucci
authors.forename: A
authors.initials: A
authors.lastname: Preti
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D000249:Adenosine Monophosphate / Q000378:metabolism*; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004798:Enzymes / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D009243:NAD / Q000378:metabolism*; D012867:Skin / Q000378:metabolism*
chemical_list: D004798:Enzymes; D009243:NAD; D000246:Adenosine Diphosphate Ribose; D000249:Adenosine Monophosphate