Cacciapaglia Roberta, Casnati Alessandro, Mandolini Luigi, Peracchi Alessio, Reinhoudt David N, Salvio Riccardo, Sartori Andrea, Ungaro Rocco
Dipartimento di Chimica and IMC - CNR Sezione Meccanismi di Reazione, Università La Sapienza, Box 34 - Roma 62, 00185 Roma, Italy.
J Am Chem Soc. 2007 Oct 17;129(41):12512-20. doi: 10.1021/ja0737366. Epub 2007 Sep 20.
Di- and trinuclear copper(II) complexes of [12]aneN3 macrocycles anchored at the upper rim of cone calix[4]arenes in 1,2-, 1,3-, and 1,2,3-positions were investigated as cleaving agents of 6-, 7-, and 17-meric oligoribonucleotides. A kinetic investigation of the cleavage reactions was carried out using gel electrophoresis to separate and analyze reactants and products having a radioactive phosphate label in the terminal 5'-position. The degree of cooperation was assessed on the basis of a comparison with rates of cleavage by mononuclear controls. A remarkable selectivity of cleavage of the CpA phosphodiester bond was observed for all metal complexes, in sharp contrast with the UpU and UpG selectivity previously observed in the cleavage of diribonucleoside monophosphates by the same metal complexes. The highest rate acceleration, brought about in the cleavage of the 5'-pCpA bond in hexanucleotide 9 by 50 muM trinuclear complex 5-Cu3 (water solution, pH 7.4, 50 degrees C), amounts to 5 x 105-fold, as based on the estimated background reactivity of the CpA dimer. Selectivity in the cleavage of oligoribonucleotides by copper(II) complexes closely resembles that experienced by ribonuclease A and by a number of metal-independent RNase A mimicks. The possible role of the dianionic phosphate at the 5'-terminal positions as a primary anchoring site for the metal catalyst is discussed.
研究了在1,2-、1,3-和1,2,3-位固定于杯[4]芳烃锥状上缘的[12]aneN3大环的双核和三核铜（II）配合物作为6-、7-和17聚体寡核糖核苷酸的切割剂。使用凝胶电泳对切割反应进行动力学研究，以分离和分析在末端5'-位带有放射性磷酸标记的反应物和产物。通过与单核对照的切割速率进行比较来评估协同程度。所有金属配合物均观察到对CpA磷酸二酯键的显著切割选择性，这与先前在相同金属配合物切割二核糖核苷单磷酸时观察到的UpU和UpG选择性形成鲜明对比。50 μM三核配合物5-Cu3（水溶液，pH 7.4，50℃）对六核苷酸9中5'-pCpA键的切割所带来的最高速率加速达到5×105倍，这是基于CpA二聚体的估计背景反应性。铜（II）配合物对寡核糖核苷酸的切割选择性与核糖核酸酶A以及一些非金属依赖性核糖核酸酶A模拟物的情况非常相似。讨论了5'-末端位置的二价磷酸根作为金属催化剂主要锚定位点的可能作用。
