Rapid Phosphodiester Hydrolysis by an Ammonium-Functionalized Copper(II) Complex. A Model for the Cooperativity of Metal Ions and NH-Acidic Groups in Phosphoryl Transfer Enzymes
Rapid Phosphodiester Hydrolysis by an Ammonium-Functionalized Copper(II) Complex. A Model for the Cooperativity of Metal Ions and NH-Acidic Groups in Phosphoryl Transfer Enzymes
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DOI：
10.1021/ja962806y
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发表时间：
1996-12
影响因子：
15
通讯作者：
E. Kövári;R. Krämer
中科院分区：
文献类型：
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作者：
E. Kövári;R. Krämer
合成了铵功能化配体[6，6 '-（Me_2HNCH_2C = C）_2bpy]_2+（L_1）和[6，6'-（Me_3NCH_2C = C）_2bpy]_2+（L_2）的铜配合物[（Ln）Cu（NO_3）_4·2（H_2O）]（n = 1：1，n = 2：2）。研究了在20 °C下在乙醇-水19：1中通过这些络合物水解活化的磷酸二酯双（对硝基苯基）磷酸盐（BNPP）。在pH6.6时，（L1）Cu和（L2）Cu的解离速率常数分别为kcat = 4.4（±0.4）× 10 ~（-3）s ~（-1）和kcat = 4（±1）× 10 ~（-6）s ~（-1）。（L1）Cu使BNPP的水解加速4 × 107倍，并且比（L2）Cu的反应性高1000倍。这表明（L1）Cu的高反应性与酸性− NMe 2 H+基团与磷酸二酯底物的相互作用有关。在晶体学表征的配合物[（L1）2Cu 2（1，3-μ-O3 POPh）2（OH 2）2]（NO3）4（3）中观察到磷酸酯通过金属配位和与一个铵基的氢键的双功能结合。（L1）Cu裂解BNPP的可能机制包括金属氢氧化物与金属离子的相互作用。
The copper(II) complexes [(Ln)Cu(NO3)4·2(H2O)] (n = 1: 1, n = 2: 2) of the ammonium-functionalized ligands [6,6‘-(Me2HNCH2C⋮C)2bpy]2+ (L1) and [6,6‘-(Me3NCH2C⋮C)2bpy]2+ (L2) were prepared. Hydrolysis of the activated phosphodiester bis(p-nitrophenyl) phosphate (BNPP) by these complexes in ethanol−water 19:1 at 20 °C was investigated. The rate constants for cleavage of the bound phosphodiester at pH 6.6 are kcat = 4.4(±0.4) × 10-3 s-1 for (L1)Cu and kcat = 4(±1) × 10-6 s-1 for (L2)Cu. (L1)Cu accelerates hydrolysis of BNPP 4 × 107-fold and is 1000 times more reactive than (L2)Cu. This suggests that the high reactivity of (L1)Cu is related to the interaction of the acidic −NMe2H+ group with the phosphodiester substrate. Bifunctional binding of a phosphate ester by metal coordination and hydrogen bonding with one ammonium group is observed in the crystallographically characterized complex [(L1)2Cu2(1,3-μ-O3POPh)2(OH2)2](NO3)4 (3). A plausible mechanism of BNPP cleavage by (L1)Cu includes metal-hydroxide att...