Human nm23-h1-protein and h2-protein have similar nucleoside diphosphate kinase-activities.

The nucleoside diphosphate kinase activity of nm23-H1 and nm23-H2 proteins was examined. Full length nm23-H1 and nm23-H2 proteins were produced in E.coli in fusion form with a 26 kDa glutathione S-transferase (GST). Affinity purified nm23-H1 and nm23-H2 formed phosphoenzyme intermediates when incubated with [gamma-P-32]ATP. The formation of GTP from GDP was also demonstrated by these two proteins by thin layer chromatography. The 26 kDa GST alone did not show similar activity. Both nm23-H1 and nm23-H2 shared very similar biochemical characteristics, namely, time kinetics, pH, temperature and cation dependency for the formation of the phosphoenzyme intermediates.