ASSAY METHOD USING NOVEL NAD SYNTHETASE AND A PROCESS FOR PRODUCTION OF THE ENZYME
A NAD synthetase having the following properties: 
(1) Action: 
at least catalyses in the presence of Mg⁺⁺ or Mn⁺⁺ ion the reaction (a):   + NAD and does not catalyse in the presence of Mg⁺⁺ ion the reaction (b);   (2) Substrate specificity: 
utilises ammonia, including ammonia in the form of an ion, as a substrate but does not utilise glutamine or asparagine as a substrate; is useful in assaying for ATP, deamide-NAD, ammonia including ammonia in the form of an ammonium ion or for a component of a reaction system in which ATP, deamide-NAD or ammonia including ammonia in the form of an ammonium ion is consumed or generated. The NAD synthetase may be prepared from any microorganism belonging to the genus  Bacillus  which produces the NAD synthetase. A preferred microorganism is  Bacillus stearothermophilus  H-8044 (FERM BP-1408).  