title: Lung contains an inhibitor for nicotinatemononucleotide pyrophosphorylase (carboxylating) of NAD biosynthesis.
abstract: Rat, cow and foal lung extracts contained an inhibitor for the liver NAD biosynthetic-pathway enzyme, nicotinatemononucleotide pyrophosphorylase (carboxylating) [EC 2.4.2.19]. The inhibitor was not dialyzable, was labile at 100 degrees C, was retained by a 30,000 dalton pore size Amicon membrane and, when partially purified by precipitation at 40-100% ammonium sulfate, inhibited the enzyme stoichiometrically. Lung reportedly does not contain nicotinate-mononucleotide pyrophosphorylase or make NAD de novo. However, the inhibitor would mask detection of the enzyme in lung extracts. We detected a low nicotinatemononucleotide pyrophosphorylase-like activity (0.003 +/- 0.001 nanomoles CO2 produced from quinolinic acid per mg of extract protein) in rat lung but none in foal or cow lung.
authors.affiliation: John M. Dalton Research Center, Columbia, MO.
authors.forename: R L
authors.initials: RL
authors.lastname: Seither
authors.forename: O R
authors.initials: OR
authors.lastname: Brown
authors.forename: B V
authors.initials: BV
authors.lastname: Babu
mesh_terms: D000645:Ammonium Sulfate; D000818:Animals; D002417:Cattle; D011232:Chemical Precipitation; D006736:Horses; D007700:Kinetics; D008168:Lung / Q000201:enzymology* / Q000378:metabolism; D009243:NAD / Q000096:biosynthesis*; D010428:Pentosephosphates / Q000378:metabolism; D010430:Pentosyltransferases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism; D051381:Rats; D013552:Swine; D014020:Tissue Extracts / Q000494:pharmacology; D000098553:Nicotinate-Nucleotide Diphosphorylase (Carboxylating)
chemical_list: D010428:Pentosephosphates; D014020:Tissue Extracts; D009243:NAD; D010430:Pentosyltransferases; D000098553:Nicotinate-Nucleotide Diphosphorylase (Carboxylating); D000645:Ammonium Sulfate