The Purification and Properties of Rat Liver Nicotinamide Adenine Dinucleotide Kinase

NAD kinase (ATP:NAD 2'-phosphotransferase, EC 2.7.1.23) has been purified from rat liver. Approximately a 1000-fold purification with a yield of 30% is routinely achieved. Preparations of up to 2000-fold purification have been achieved with a yield of 3 to 5%. The apparent Km values for NAD and ATP are 1.4 and 7.0 mm, respectively. The Vmax was calculated to be 21 µmoles of NADP formed per mg of protein per hour. The pH optimum is around 7.0. The enzyme is stable at pH 9 to 10. Rapid loss in activity occurs at lower pH values. Mg++ is essential for enzymatic activity. Mn++ can substitute for Mg++, as can to a lesser extent, Zn++ and Fe++.