Intermolecular CH···O/N H-bonds in the biologically important pairs of natural nucleobases: a thorough quantum-chemical study

Abstract

This study aims to cast light on the physico-chemical nature and energetic of the non-conventional CH···O/N H-bonds in the biologically important natural nucleobase pairs using a comprehensive quantum-chemical approach. As a whole, the 36 biologically important pairs, involving canonical and rare tautomers of nucleobases, were studied by means of all available up-to-date state-of-the-art quantum-chemical techniques along with quantum theory "Atoms in molecules" (QTAIM), Natural Bond Orbital (NBO) analysis, Grunenberg's compliance constants theory, geometrical and vibrational analyses to identify the CH···O/N interactions, reveal their physico-chemical nature and estimate their strengths as well as contribution to the overall base-pairs stability. It was shown that all the 38 CH···O/N contacts (25 CH···O and 13 CH···N H-bonds) completely satisfy all classical geometrical, electron-topological, in particular Bader's and "two-molecule" Koch and Popelier's, and vibrational criteria of H-bonding. The positive values of Grunenberg's compliance constants prove that the CH···O/N contacts in nucleobase pairs are stabilizing interactions unlike electrostatic repulsion and anti-H-bonds. NBO analysis indicates the electron density transfer from the lone electron pair of the acceptor atom (O/N) to the antibonding orbital corresponding to the donor group σ(∗)(CH). Moreover, significant increase in the frequency of the out-of-plane deformation modes γ (CH) under the formation of the CH···O (by 17.2÷81.3/10.8÷84.7 cm(-1)) and CH···N (by 32.7÷85.9/9.0÷77.9 cm(-1)) H-bonds at the density functional theory (DFT)/second-order Møller-Plesset (MP2) levels of theory, respectively, and concomitant changes of their intensities can be considered as reliable indicators of H-bonding. The strengths of the CH···O/N interactions, evaluated by means of Espinosa-Molins-Lecomte formula, lie within the range 0.45÷3.89/0.62÷4.10 kcal/mol for the CH···O H-bonds and 1.45÷3.17/1.70÷3.43 kcal/mol for the CH···N H-bonds at the DFT/MP2 levels of theory, respectively. We revealed high linear mutual correlations between the H-bond energy and different physico-chemical parameters of the CH···O/N H-bonds. Based on these observations, the authors asserted that the most reliable descriptors of the H-bonding are the electron density ρ at the СН···О/N H-bond critical points and the NBO calculated stabilization energy E((2)). The linear dependence of the H-bond energy ECH···O/N (in kcal/mol) on the electron density ρ (in atomic units) was established (DFT/MP2): ECH···O = 248.501[Formula: see text]ρ-0.367/260.518[Formula: see text]ρ-0.373 and ECH···N = 218.125[Formula: see text]ρ-0.339/243.599[Formula: see text]ρ-0.441. Red-shifted and blue-shifted CH···O/N H-bonds behave in a similar way and can be described with the same fit parameters. It was found that the A-U HH2 and U-U3 nucleobase pairs are stabilized solely by the CH···O/N H-bonds. At the same time, in the A-U HH1, A-U HH2, A-Asyn 1, A-Asyn 2, A-Asyn 3, A-A4, A-G1, A-G2, G-U1, G-U2, G-U3, G-C HH1, U-U1, U-...

Structural significance of modified nucleoside 5-taurinomethyl-2-thiouridine, τm5s2U, found at ‘wobble’ position in anticodon loop of human mitochondrial tRNALys

“…5i) maintained throughout the 5-ns MD simulation. Such bifurcated interactions have been found useful in many biological processes [44,[71][72][73][74][75][76].These intramolecular interactions within the 5-taurinomethyl side chain and phosphate backbone resulted in keeping the Watson-crick base pairing sites free during the translation process. The hydrogen bonding interaction between O4 0 …HC(6) has been vanished throughout the 5-ns MD simulation (Fig.…”

A Study of the Solvation Structure of l‐Leucine in Alcohol–Water Binary Solvents through Molecular Dynamics Simulations and FTIR and NMR Spectroscopy

“…[32] Most of the previous research on blue-shifting hydrogen bonds have been conducted using theoreticalc alculation techniques. [33][34][35][36][37][38][39] However,e xperimental results on blue-shifting hydrogen bonds are much scarcer than the theoretical ones. [40][41][42] In particular,b lue-shifting hydrogen bonds have not been observed in the promotion of the secondary structure of biomolecules by TFE and HFIP at the microscopic level, despite the NOE observation of the interactions between the hydrophobic moieties of biomolecules and fluorinated alcohols.…”

Under what conditions does G•C watson-crick DNA base pair acquire all four configurations characteristic for A•T watson-crick DNA base pair?

“…В ідомо, що вотсон-криківська пара ос-нов аденін⋅тимін (А⋅Т WC) [1], що стабілізується трьома кооперативними [2] міжмолекулярними Н-зв'язками N6H…O4, N3H…N1 i C2H….O2 [3,4], які взаємно по-силюють один одного [5], може набувати ще трьох воднево-зв'язаних конфігурацій, а саме-А⋅Т rWC [6], А⋅Т H [7][8][9][10][11] i А⋅Т rH [12,13]. Усі ці чотири конфігурації пари А⋅Т є біологічно важливими.…”