title: The organization of divalent cations in the active site of cadmium Escherichia coli fructose-1,6-bisphosphate aldolase.
abstract: Previously determined crystal structures of the zinc enzyme Escherichia coli class II fructose-1,6-bisphosphate aldolase display good agreement for the protein structure but a differing metal-ion organization in the active site. The structure of the enzyme with Cd(2+) in place of Zn(2+) has now been determined to 2.0 A resolution to facilitate cation identification. The protein structure was essentially identical to other structures and five Cd(2+) positions were identified. Two of the cations are at the active site; one corresponds to the catalytic ion and the other provides a structural contribution. These Cd(2+) sites are equivalent to two Zn(2+) ions observed when the enzyme is complexed with a transition-state mimic and confirm our assignment of the roles played by these ions.
authors.affiliation: Division of Biological Chemistry and Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland.
authors.forename: David R
authors.initials: DR
authors.lastname: Hall
authors.forename: Lauris E
authors.initials: LE
authors.lastname: Kemp
authors.forename: Gordon A
authors.initials: GA
authors.lastname: Leonard
authors.forename: Karen
authors.initials: K
authors.lastname: Marshall
authors.forename: Alan
authors.initials: A
authors.lastname: Berry
authors.forename: William N
authors.initials: WN
authors.lastname: Hunter
mesh_terms: D001665:Binding Sites; D002104:Cadmium / Q000737:chemistry*; D002384:Catalysis; D002412:Cations / Q000737:chemistry; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology*; D005634:Fructose-Bisphosphate Aldolase / Q000737:chemistry* / Q000302:isolation & purification; D008958:Models, Molecular; D015032:Zinc / Q000737:chemistry
chemical_list: D002412:Cations; D002104:Cadmium; D005634:Fructose-Bisphosphate Aldolase; D015032:Zinc