Nicotinamide Mononucleotide Pyrophosphorylase Activity in Animal Tissues

An enzyme which catalyzes the formation of nicotinamide mononucleotide in the presence of nicotinamide, 5-phosphoribosylpyrophosphate, adenosine triphosphate, and Mg ++ has been purified from rat liver. The reaction is highly specific for ATP and is not substituted for by a variety of nucleotides. E...

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Bibliographic Details
Published inThe Journal of biological chemistry Vol. 241; no. 1; pp. 188 - 191
Main Authors Dietrich, L S, Fuller, L, Yero, I L, Martinez, L
Format Journal Article
LanguageEnglish
Published United States American Society for Biochemistry and Molecular Biology 10.01.1966
Subjects
Adenosine Triphosphate
Animals
Diphosphates
Hydrogen-Ion Concentration
In Vitro Techniques
Kinetics
Liver - enzymology
Magnesium
Niacinamide
Phosphotransferases - metabolism
Rats
Subcellular Fractions - metabolism
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Summary:An enzyme which catalyzes the formation of nicotinamide mononucleotide in the presence of nicotinamide, 5-phosphoribosylpyrophosphate, adenosine triphosphate, and Mg ++ has been purified from rat liver. The reaction is highly specific for ATP and is not substituted for by a variety of nucleotides. Enzymic activity has been found in all of the tissues studied, and in the crude homogenate it is apparently in an inhibited state. The inhibitor is removed by protamine sulfate. A broad activity peak is observed between pH 7.5 and 9.5 with maximal activity around pH 8. The enzymic activity is stable at these pH values, but it is acid labile. The apparent K m values for nicotinamide, PP-ribose-P, and ATP are 2.62 µ m , 3.57 x 10 -5 m , and 3.83 x 10 -4 m , respectively. The V max was calculated to be 5.4 mµmoles per mg of protein per hour.
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ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)96977-2