1.1.1.16	Ba2+	activates	
1.1.1.16	Ca2+	activates	
1.1.1.16	Co2+	activates	
1.1.1.16	Mg2+	required, the enzyme contains one magnesium atom per dimer, consistent with the presence of a structural metal ion. The homotetrameric enzyme contains two Mg2+ binding sites	
1.1.1.16	Mn2+	activates