J Biomol Struct Dyn
Institute of Molecular Biology and Genetics, The National Academy of Sciences of Ukraine, Kiev.
Published: August 2001
A quantum mechanical study of all cis-syn cyclobutane pyrimidine photodimers including the normal and rare tautomeric forms of bases has been performed using the ab initio method at HF/6-31G(d.p), MP2(fc)//HF/6-31G(d,p) and MP2(fc)/6-31G(d,p) levels. A puckering angle of the cyclobutyl ring and twist angle of pyrimidine rings with respect to each other is well described by these calculations. It is predicted that in the gas phase all photodimers containing the rare imino form of cytosine are more stable than those containing its normal form. The Monte Carlo simulations show that the dimer containing the imino form of cytosine is more stabilized by water cluster than that containing its amino forms. The possible biological significance stems from the fact that the cytosine in the dimer directs the incorporation of adenine in the complementary strand during replicative bypass. Data obtained point to the cytosine tautomerism as a possible mechanism for the origin of UV-induced mutation.
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http://dx.doi.org/10.1080/07391102.2001.10506730 | DOI Listing |
J Am Chem Soc
January 2025
Department of Chemistry and Nuclear Science & Engineering Center, Colorado School of Mines, Golden, Colorado 80401, United States.
The and isomers of [Sm(dicyclohexano-18-crown-6)(HO)]I exhibiting water molecules bound to the Sm ion have been isolated and characterized. Sm possesses an electrochemical potential sufficient for water reduction, and thus these complexes add to the recent body of evidence that the oxidation of Sm by water can operate by a mechanism that is not straightforward. These complexes are obtained by the direct addition of stoichiometric amounts of water to solutions of the respective Sm(dicyclohexano-18-crown-6)I isomers under an inert atmosphere.
View Article and Find Full Text PDFJ Phys Chem B
August 2024
Center for Quantum Technology Research, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China.
Microbial rhodopsin, a pivotal photoreceptor protein, has garnered widespread application in diverse fields such as optogenetics, biotechnology, biodevices, etc. However, current microbial rhodopsins are all transmembrane proteins, which both complicates the investigation on the photoreaction mechanism and limits their further applications. Therefore, a specific mimic for microbial rhodopsin can not only provide a better model for understanding the mechanism but also can extend the applications.
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September 2023
Institute of Atomic and Molecular Sciences Academia Sinica, No 1., Sec. 4 Roosevelt Rd., Taipei, 10617, Taiwan.
Criegee intermediates (CIs), R R COO, are active molecules produced in the atmosphere from the ozonolysis of alkenes. Here, we systematically evaluated the reactivity of ten CIs with carbon monoxide and carbon dioxide using CCSD(T)-F12/cc-pVTZ-F12//B3LYP/6-311+G(2d,2p) energies and transition state theory. Many previous studies focused on alkyl substitution, but here we evaluated both alkyl and vinyl substitution toward the reactivity by studying five anti-type CIs: CH OO, anti-CH CHOO, anti-cis-C H CHOO, anti-trans-MACRO, anti-cis-MACRO; and five syn-type CIs: syn-CH CHOO, (CH ) COO, syn-trans-C H CHOO, syn-trans-MVKO, and syn-cis-MVKO.
View Article and Find Full Text PDFChem Asian J
August 2022
Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai, 400076, India.
A stereoselective [3+2] cycloaddition approach to functionalized pentaquinanes starting from cis-syn-cis triquinanes, derived from Cookson's diones, is reported. This transformation involves generation of six new stereocenters in a single step leading to cis-anti-cis-syn-cis-anti-cis polyquinane systems. Our method prevents transannular cyclizations which are prevalent in these moieties.
View Article and Find Full Text PDFBioorg Med Chem
January 2022
Department of Chemistry & Chemical Biology, Indiana University-Purdue University Indianapolis (IUPUI), 402 N. Blackford St., Indianapolis, IN 46202, United States. Electronic address:
Cyclobutane pyrimidine dimers (CPDs) are the most abundant mutagenic DNA lesions formed in mammalian cells upon exposure to UV-B radiation (280-315 nm) in sunlight. These lesions are thought to be chemically stable and to withstand high concentrations of acids and bases.While earlier investigations of DNA lesions containing saturated pyrimidines have shown that the C4 carbonyl is a potential target of nucleophilic attack, similar reactions with thymine nucleobase model CPDs clearly showed that the cis-syn CPD (major isomer) is stable in the presence of a high concentration of alkali at room temperature.
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