The organization of divalent cations in the active site of cadmium Escherichia coli fructose-1,6-bisphosphate aldolase.
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Hall DR, Kemp LE, Leonard GA, Marshall K, Berry A, Hunter WN
The organization of divalent cations in the active site of cadmium Escherichia coli fructose-1,6-bisphosphate aldolase.
Acta Crystallogr D Biol Crystallogr. 2003 Mar;59(Pt 3):611-4. Epub 2003 Feb 21.
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- 12595741 [ View in PubMed]
- 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.