Structural studies of the [tris(imidazolyl)phosphine]metal nitrate complexes [[PimPrl,But]M(NO3)]+ (M = Co, Cu, Zn, Cd, Hg): comparison of nitrate-binding modes in synthetic analogues of carbonic anhydrase.
Structural studies of the [tris(imidazolyl)phosphine]metal nitrate complexes [[PimPrl,But]M(NO3)]+ (M = Co, Cu, Zn, Cd, Hg): comparison of nitrate-binding modes in synthetic analogues of carbonic anhydrase.
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DOI：
10.1021/ic990682v
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发表时间：
2000-02
影响因子：
4.6
通讯作者：
C. Kimblin;V. Murphy;T. Hascall;B. Bridgewater;J. Bonanno;G. Parkin
中科院分区：
文献类型：
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作者：
C. Kimblin;V. Murphy;T. Hascall;B. Bridgewater;J. Bonanno;G. Parkin
X射线衍射研究了一系列以三（1-异丙基-4-叔丁基咪唑基）膦配体[[PimPri，But]M（NO3）]+（M = Co，Cu，Zn，Cd，Hg）为载体的阳离子二价金属硝酸盐配合物，表明硝酸盐配体的配位模式强烈依赖于金属。除了HgII衍生物之外，硝酸根配体配位模式与金属取代的碳酸酐酶的活性相关，使得只有MII-碳酸酐酶表现出显著的活性，即，Zn和Co物种是[[PimPri，But]M（NO3）]+络合物具有强不对称硝酸根配体的那些。这种趋势支持这样的观点，即获得单齿而不是双齿碳酸氢盐中间体可能是显著碳酸酐酶活性的关键要求。有趣的是，在系列的第12族配合物，[[PimPri，但]M（NO3）]+（M = Zn，Cd，Hg），硝酸盐的配位模式，不表现出单调的周期性趋势：二价性是更大的镉络合物比锌或汞络合物。由于汞II-碳酸酐酶是不活跃的，硝酸盐的协调模式和酶活性之间的相关性是异常的汞络合物。因此，它是建议，汞II-碳酸酐酶的不活动可能是汞中心的汞在汞II-碳酸酐酶结合水的倾向降低的后果。
X-ray diffraction studies on a series of cationic divalent metal nitrate complexes supported by the tris(1-isopropyl-4-tert-butylimidazolyl)phosphine ligand, [[PimPri,But]M(NO3)]+ (M = Co, Cu, Zn, Cd, Hg), demonstrate that the nitrate ligand coordination mode is strongly dependent upon the metal. With the exception of that for the HgII derivative, the nitrate ligand coordination modes correlate with the activities of metal-substituted carbonic anhydrases, such that the only MII-carbonic anhydrases which exhibit significant activity, i.e., the Zn and Co species, are those for which the [[PimPri,But]M(NO3)]+ complexes possess strongly asymmetric nitrate ligands. This trend supports the notion that access to a unidentate, rather than a bidentate, bicarbonate intermediate may be a critical requirement for significant carbonic anhydrase activity. Interestingly, the nitrate coordination modes in the series of group 12 complexes, [[PimPri,But]M(NO3)]+ (M = Zn, Cd, Hg), do not exhibit a monotonic periodic trend: the bidenticity is greater for the cadmium complex than for either the zinc or mercury complexes. Since HgII-carbonic anhydrase is inactive, the correlation between nitrate coordination mode and enzyme activity is anomalous for the mercury complex. Therefore, it is suggested that the inactivity of HgII-carbonic anhydrase may be consequence of the reduced tendency of the mercury center in HgII-carbonic anhydrase to bind water.