AI Article Synopsis
- - The study investigates double proton transfer reactions in guanine-cytosine (GC) complexes using a specific computational approach, finding that most processes occur via a concerted mechanism, except for one specific adduct (GC6OH).
- - The research identifies that the 8OHGC complex is the most stable of those examined, being 1.2 kcal/mol more stable than the nonradical GC base pair, with solvent effects notably reducing dissociation energy.
- - The reactions are generally endothermic (requiring energy), and findings suggest a negative charge on guanine and a positive one on cytosine in the adducts, indicating that the formation of partial ion pairs could hinder the thermodynamic favorability
Article Abstract
Double proton transfer (PT) reactions in guanine-cytosine OH radical adducts are studied by the hybrid density functional B3LYP approach. Concerted and stepwise proton-transfer processes are explored between N1(H) on guanine (G) and N3 on cytosine (C), and between N4(H) on C and O6 on G. All systems except GC6OH display a concerted mechanism. 8OHGC has the highest dissociation energy and is 1.2 kcal/mol more stable than the nonradical GC base pair. The origin of the interactions are investigated through the estimation of intrinsic acid-basic properties of the *OH-X monomer (X = G or C). Solvent effects play a significant role in reducing the dissociation energy. The reactions including *OH-C adducts have significantly lower PT barriers than both the nonradical GC pair and the *OH-G adducts. All reactions are endothermic, with the GC6OH --> GC6OHPT reaction has the lowest reaction energy (4.6 kcal/mol). In accordance with earlier results, the estimated NBO charges show that the G moiety carries a slight negative charge (and C a corresponding positive one) in each adduct. The formation of a partial ion pair may be a potential factor leading to the PT reactions being thermodynamically unfavored.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/jp071772l | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
A comprehensive mechanistic investigation of sustainable carbene N-H insertion catalyzed by engineered His-ligated heme proteins.
Catal Sci Technol
January 2025
Department of Chemistry and Chemical Biology, Stevens Institute of Technology 1 Castle Point Terrace Hoboken NJ 07030 USA
Engineered heme proteins possess excellent biocatalytic carbene N-H insertion abilities for sustainable synthesis, and most of them have His as the Fe axial ligand. However, information on the basic reaction mechanisms is limited, and ground states of heme carbenes involved in the prior computational mechanistic studies are under debate. A comprehensive quantum chemical reaction pathway study was performed for the heme model with a His analogue as the axial ligand and carbene from the widely used precursor ethyl diazoacetate with aniline as the substrate.
View Article and Find Full Text PDFAPT imaging of hepatocellular carcinoma signals an effective therapeutic response in advance of tumor shrinkage.
Hepat Oncol
December 2024
Advanced Imaging Research Center, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA.
The aim of this study was to assess the utility of weighted amide proton transfer (APT) MRI in three different rodent models of hepatocellular carcinoma (HCC). APT MRI was evaluated in models of diethylnitrosamine (DEN) induced HCC, N1S1 syngeneic orthotopic xenograft and human HepG2 ectopic xenograft. All models of HCC showed a higher APT signal over the surrounding normal tissues.
View Article and Find Full Text PDFElectrochemically Driven Selective Olefin Epoxidation by Cobalt-TAML Catalyst.
J Am Chem Soc
January 2025
Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, South Korea.
Epoxides are versatile chemical intermediates that are used in the manufacture of diversified industrial products. For decades, thermochemical conversion has long been employed as the primary synthetic route. However, it has several drawbacks, such as harsh and explosive operating conditions, as well as a significant greenhouse gas emissions problem.
View Article and Find Full Text PDFProtonolysis and Condensation Reactions of Alkoxido-Substituted Lindqvist {MW} and Keggin {MPW} Polyoxometalates: Comparative Experimental and Modeling Studies.
Inorg Chem
January 2025
NUPOM Lab, Chemistry, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
An understanding of proton transfer and migration at the surfaces of solid metal oxides and related molecular polyoxometalates (POMs) and metal alkoxides is crucial for the development of reactivity involving protonation or the absorption/binding of water. In this work, the hydrolysis of alkoxido Ti- and Sn-substituted Lindqvist [(MeO)MWO] (M = Ti, ; M = Sn, ) and Keggin [(MeO)MPWO] (M = Ti, ; M = Sn, ) type polyoxometalates (POMs) to hydroxido derivatives and subsequent condensation to μ-oxido species has been investigated in detail to provide insight into proton transfer reactions in these molecular metal oxide systems. Solution NMR studies revealed the dependence of reactions not only on the nature of the heteroatom (Ti or Sn) but also on the type of lacunary (W or PW) POM and also on the solvent (MeCN or DMSO).
View Article and Find Full Text PDFCoordination-regulated copper single-atom active sites for electrochemical reduction of nitrate to ammonia.
Chem Commun (Camb)
January 2025
College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China.
The electrochemical conversion of nitrate to ammonia is necessary to restore the globally perturbed nitrogen cycle. Herein, the regulated coordination of active Cu single atoms to selectively modulate the energy barriers of proton-electron transfer steps was investigated and offered valuable insights for improving the selectivity and kinetics of the NORR.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!