1.1.2.8	treatment with trans-l,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid at 30°C leads to an catalytically inactive apo-form. Upon incubation of the apo-form with Ca2+ and pyrroloquinoline quinone a fully active holo-enzyme is reconstituted. Incubation of apo-enzyme with Sr2+ and pyrroloquinoline quinone leads to the formation of an active Sr2+-form. The Sr2+ and the Ca2+-forms of the enzyme differ in their absorption spectra.	701600