Nicotinamide Adenine Dinucleotide Kinase from Azotobacter vinelandii

A method is described for the purification of NAD+ kinase from extracts of Azotobacter vinelandii (ATCC 9104) cells. The specific activity of the purified enzyme is the highest so far reported. The enzyme requires a metal ion for activity. There is a lack of specificity for the nature of the phosphate donor in the kinase reaction. The Michaelis constants for the enzyme substrates have been determined by a direct spectrophotometric assay method which is described. The enzyme is protected to a remarkable extent from heat inactivation by NAD+. The enzyme appears to be a sulfhydryl enzyme; the sulfhydryl groups are protected by NAD+.