Purity: > 95% by SDS - PAGE Format: Liquid. 20mM Tris-HCl buffer (pH8.0) containing 10% glycerol, 0.1M NaCl,1mM DTT. ndk, also known as Nucleoside diphosphate kinase, is an enzyme that catalyzes the exchange of phosphate groups between different nucleoside diphosphates. This protein activity maintains an equilibrium between the concentrations of different nucleoside triphosphates such as, for example, when GTP produced in the citric acid (Krebs) cycle is converted to ATP. Recombinant E. coli ndk protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.