1.1.1.87 K+ activates 696220 1.1.1.87 K+ dependent on 696350, 722303 1.1.1.87 K+ required 660918 1.1.1.87 K+ required for optimal activity 644539, 644540 1.1.1.87 K+ the enzyme requires a potassium ion as an activator, for optimal binding of NAD+ 739958 1.1.1.87 Mg2+ - 667934, 669109, 685232, 685539 1.1.1.87 Mg2+ activates, increase in the affinity of enzyme for Mg-HIc as a result of elimination of the inhibitory effect of Cl- 696220 1.1.1.87 Mg2+ activation, 2fold activity at 5 mM 644543 1.1.1.87 Mg2+ dependent on 696350, 722303 1.1.1.87 Mg2+ essentially required 722569 1.1.1.87 Mg2+ Mn2+ or Mg2+ is required for this activity, and stronger activity is observed with Mn2+ 760522 1.1.1.87 Mg2+ required 644540, 644541 1.1.1.87 Mg2+ required, three conserved aspartate residues, D243, D267 and D271, coordinate Mg2+, which is also coordinated to the alpha-carboxylate and alpha-hydroxyl of homoisocitrate 739958 1.1.1.87 Mg2+ stimulation of oxidative decarboxylation, required for reductive carboxylation 644539 1.1.1.87 Mn2+ - 660907 1.1.1.87 Mn2+ Mn2+ or Mg2+ is required for this activity, and stronger activity is observed with Mn2+ 760522 1.1.1.87 Mn2+ required 660918 1.1.1.87 Mn2+ stimulation of oxidative decarboxylation 644539, 644540 1.1.1.87 additional information selectivity of the activator site for monovalent ions, K+ is the best activator, and NH4+ and Rb+ are also activators of the reaction, while Cs+, Li+, and Na+ are not, overview. Substitution of potassium acetate for KCl changes the kinetic mechanism of HIcDH from a steady state random to a fully ordered mechanism with the binding of Mg-HIc followed by K+ and NAD+ 696220 1.1.1.87 NH4+ activates 696220 1.1.1.87 Rb+ activates 696220