3.6.1.25 R265H no AdoMet synthetase activity, normal tripolyphosphatase activity 3.6.1.25 R265S no AdoMet synthetase activity, reduced tripolyphosphatase activity 3.6.1.25 K85A the His-tagged mutant is about 10times less active than the wild type enzyme, but the optimal conditions for activity are essentially the same. The mutant is more strongly activated by Mn2+ than by Mg2+, and the inhibitory effects of Ca2+ and Zn2+ are less pronounced 3.6.1.25 K52R the His-tagged mutant loses 90-99% of its activity (catalytic efficiency is at least 1000times lower) compared to the wild type enzyme. Mn2+ does not induce a significant activation of this mutant 3.6.1.25 K8A the His-tagged mutant remains highly active with tripolyphosphate as substrate and Mg2+ as activator, with a catalytic efficiency close to that of the recombinant wild type enzyme