In the current study, we investigated the detailed reaction mechanism of [Pd(en)(H2O)(2)](2+) binding to the N1 deprotonated 9-methylguanine formation of various corner adducts and revealed the most viable structure of the tetramer of [{Pd(en)(guanine)}(4)](4+) by OFT and ab initio calculations. Our calculations indicate that in the first substitution reactions the palladination N7 of guanine is preferred over N1 in kinetics and thermodynamics. The first substituted adducts can further bind to MeG forming corner adducts. There are three possible linkages for corner adducts: N7-Pd-N7, N7-Pd-N1, and N1-Pd-N1. Each product has two conformations, the head to head arrangement (HH) in which the C=O6 of two MeG are arranged on the same side of the coordination plane, and head to tail (HT) in which the C=O6 of two MeG are located on the opposite side of the plane. Generally, the HT arrangements are more favorable over the HH conformation. The reaction of [Pd(en)(H2O)N(7)MeG](+) binding to the N7 of MeG giving the corner adduct of [Pd(en){N(7)MeG}(2)] in HT conformation is most favorable in kinetics with activation free energy at 10.1 kcal/mol. However, our calculations for [{Pd(en)(guanine)}(4)](4+) demonstrate that the tetramer adopts a structure of -N1-Pd-N7- linkage. Our NBO analysis clearly illustrates that the -NH2 center dot center dot center dot O=C hydrogen bonds are cooperatively formed among four guanines, which play a pivotal role in stabilizing the tetramer. The analysis of the reaction energies for reactions giving various adducts suggests that the formation of the tetramer adduct is thermodynamically controlled. (C) 2011 Elsevier B.V. All rights reserved.
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Univ S Bohemia, Fac Hlth & Social Studies, Dept Biophys, Ceske Budejovice 37011, Czech RepublicUniv S Bohemia, Fac Hlth & Social Studies, Dept Biophys, Ceske Budejovice 37011, Czech Republic
Chval, Zdenek
Sip, Miroslav
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Univ S Bohemia, Fac Hlth & Social Studies, Dept Biophys, Ceske Budejovice 37011, Czech RepublicUniv S Bohemia, Fac Hlth & Social Studies, Dept Biophys, Ceske Budejovice 37011, Czech Republic
Sip, Miroslav
Burda, Jaroslav V.
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Charles Univ Prague, Fac Math & Phys, Dept Chem Phys & Opt, CR-12116 Prague 2, Czech RepublicUniv S Bohemia, Fac Hlth & Social Studies, Dept Biophys, Ceske Budejovice 37011, Czech Republic
机构:
Univ S Bohemia, Fac Hlth & Social Studies, Dept Biophys, Ceske Budejovice 37011, Czech RepublicUniv S Bohemia, Fac Hlth & Social Studies, Dept Biophys, Ceske Budejovice 37011, Czech Republic
Chval, Zdenek
Sip, Miroslav
论文数: 0引用数: 0
h-index: 0
机构:
Univ S Bohemia, Fac Hlth & Social Studies, Dept Biophys, Ceske Budejovice 37011, Czech RepublicUniv S Bohemia, Fac Hlth & Social Studies, Dept Biophys, Ceske Budejovice 37011, Czech Republic
Sip, Miroslav
Burda, Jaroslav V.
论文数: 0引用数: 0
h-index: 0
机构:
Charles Univ Prague, Fac Math & Phys, Dept Chem Phys & Opt, CR-12116 Prague 2, Czech RepublicUniv S Bohemia, Fac Hlth & Social Studies, Dept Biophys, Ceske Budejovice 37011, Czech Republic