The organization of divalent cations in the active site of cadmium Escherichia coli fructose-1,6-bisphosphate aldolase
The organization of divalent cations in the active site of cadmium Escherichia coli fructose-1,6-bisphosphate aldolase
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DOI：
10.1107/s0907444902023661
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发表时间：
2003-03-01
期刊：
影响因子：
--
通讯作者：
Hunter, WN
中科院分区：
文献类型：
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作者：
Hall, DR;Kemp, LE;Hunter, WN
先前确定的锌酶大肠杆菌II类果糖-1,6-二磷酸醛缩酶的晶体结构与蛋白质结构一致，但活性位点的金属离子组织不同。酶的结构以Cd2+代替Zn2+，现在已确定为2.0埃分辨率，以方便阳离子识别。蛋白质结构与其他结构基本相同，并确定了5个Cd2+位置。两个阳离子在活性位点；一个对应于催化离子，另一个提供结构贡献。这些Cd2+位点相当于酶与过渡态模拟物络合时观察到的两个Zn2+离子，并证实了这些离子所起作用的分配。
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 Cd2+ in place of Zn2+ has now been determined to 2.0 Angstrom resolution to facilitate cation identification. The protein structure was essentially identical to other structures and five Cd2+ 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 Cd2+ sites are equivalent to two Zn2+ ions observed when the enzyme is complexed with a transition-state mimic and confirm our assignment of the roles played by these ions.