Open AccessNicotinamide Mononucleotide Determination of its Enzymatic Formation in vitro and its Physiological Rôle for the Biosynthesis of Nicotinamide‐Adenine Dinucleotide in Mice
Author(s) -
Streffer Christian,
Beneš Jiri
Publication year - 1971
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1971.tb01477.x
Subject(s) - nicotinamide mononucleotide , nad+ kinase , nicotinamide , nicotinamide adenine dinucleotide , pyrophosphate , nicotinamide phosphoribosyltransferase , chemistry , enzyme , biosynthesis , biochemistry , niacinamide , nucleotide , metabolism , microbiology and biotechnology , biology , gene
1 A method is described to measure the activity of the NMN pyrophosphorylase (NMN: pyrophosphate phosphoribosyltransferase) in crude extracts of mouse tissues. The homogenate is incubated with 5‐phosphoribose‐1‐pyrophosphate, ATP, Mg 2+ and [ 14 C]nicotinamide in the presence of unlabelled NMN. Optimal conditions for the enzymatic assay were determined. 2 The NMN pyrophosphorylase activity was measured in several organs of mice by this method. The observed activites were found to be considerably higher than reported in the literature. 3 The formation of 14 C‐labelled pyridine nucleotides in mouse liver after intraperitoneal injection of [ 14 C]nicotinamide was studied. After the application of a high nicotinamide dose (1 mmole/kg) the biosynthesis of NAD was mainly via nicotinate. However, after the injection of a small nicotinamide dose within the physiological range the pathway via NMN is utilized to a large extent. Under these conditions a partial inhibition of the metabolic pathway of nicotinate to NAD has no influence on the NAD formation from nicotinamide. It is concluded that NMN is the physiological intermediate for NAD biosynthesis from nicotinamide.