5.1.99.1 Co2+ 0.4 mM, 4fold increase in activity. Presence of Co2+ restores activity after incubation with EDTA 693174 5.1.99.1 Co2+ activates 726729 5.1.99.1 Co2+ enzyme is metal-dependent enzyme, in the active site, metal binding site binds the coenzyme Co2+ 706660 5.1.99.1 Co2+ increases activity 2437, 2442 5.1.99.1 Co2+ most potent activator, Km: 0.0002 mM, binds 2 mol Co2+ per mol of racemase 2434 5.1.99.1 Co2+ the enzyme is activated by divalent cations (Ni2+, Co2+, and Mg2+) 726729 5.1.99.1 Co3+ lower level of activation than Co2+ at higher concentrations 2442 5.1.99.1 Fe2+ lower level of activation than Co2+ at higher concentrations 2442 5.1.99.1 Mg2+ activates 726729 5.1.99.1 Mg2+ the enzyme is activated by divalent cations (Ni2+, Co2+, and Mg2+) 726729 5.1.99.1 Mn2+ increases activity to a smaller extent than Co2+ 2437 5.1.99.1 Mn2+ lower level of activation than Co2+ at higher concentrations 2442 5.1.99.1 Mn2+ presence of Mn2+ restores activity after incubation with EDTA 693174 5.1.99.1 additional information enzyme does not require tightly bound metal ions for activity, they are not released even after extensive dialysis at pH 2.4 2437 5.1.99.1 additional information His12, Gln65, His91 and Glu141 provide a binding site for a divalent metal ion, as shown by binding of Co2+ 653930 5.1.99.1 additional information no activation of enzyme with Mg2+, Ni2+ 693174 5.1.99.1 Ni2+ activates 726729 5.1.99.1 Ni2+ increases activity to a smaller extent than Co2+ 2437 5.1.99.1 Ni2+ the enzyme is activated by divalent cations (Ni2+, Co2+, and Mg2+) 726729 5.1.99.1 Zn2+ increases activity to a smaller extent than Co2+ 2437