title: Effects of zinc and other metal ions on the stability and activity of Escherichia coli alkaline phosphatase.
abstract: Measurement of the ultraviolet circular dichroism of apo-(alkaline phosphatase) in urea solutions showed substantial denaturation in 3m-urea. A zinc-deficient mutant alkaline phosphatase behaved similarly. The stability of the enzyme in 6m-urea was followed as a function of its zinc content and was found to be dependent on the first two of the four zinc atoms bound by apoenzyme. Phosphatase activity was mostly dependent on a second pair of zinc atoms. Mn(2+), Co(2+), Cu(2+) or Cd(2+) also restored structural stability. Sedimentation-velocity and -equilibrium experiments revealed that dissociation of the dimer accompanied apoenzyme denaturation in urea concentrations of 1m or higher, without treatment with disulphide-reducing agent.
mesh_terms: D000469:Alkaline Phosphatase; D001665:Binding Sites; D002104:Cadmium; D002498:Centrifugation; D002942:Circular Dichroism; D003035:Cobalt; D003300:Copper; D004220:Disulfides; D004926:Escherichia coli / Q000201:enzymology; D008345:Manganese; D011489:Protein Denaturation; D014466:Ultraviolet Rays; D014508:Urea; D015032:Zinc
chemical_list: D004220:Disulfides; D002104:Cadmium; D003035:Cobalt; D008345:Manganese; D003300:Copper; D014508:Urea; D000469:Alkaline Phosphatase; D015032:Zinc