The collision-induced dissociation of the protonated cytosine-guanine pair was studied using tandem mass spectrometry (MS) coupled to infrared multiple photon dissociation spectroscopy with the free electron laser at Orsay (CLIO) to determine the structure of the CH and GH ionic fragments. The results were rationalized with the help of electronic structure calculations at the density functional theory level with the B3LYP/6-311++G(3df,2p) method. Several tautomers of each fragment were identified for the first time, some of which were previously predicted by other authors. In addition, two unexpected and minor tautomers were also found: cytosine keto-imino [CKI(1,2,3,4)H] and guanine keto-amino [GKA(1,3,7)H]. These results highlight the importance of the DNA base tautomerization assisted by inter- and intramolecular proton or hydrogen transfer within the protonated pairs.
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http://dx.doi.org/10.1021/acs.jpca.1c10651 | DOI Listing |
Acta Crystallogr E Crystallogr Commun
January 2025
Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522, Japan.
The title compounds, CHO ( and ), are tetra-cyclic benzoates composed of a taxane ring with a fused dioxolane ring as the core skeleton. In compound , the five-membered dioxolane ring is essentially planar while the two cyclo-hexane rings and the cyclo-octane ring adopt chair and chair-chair forms, respectively, and there are three intra-molecular H⋯H short contacts. The corresponding ring conformations in are similar; however, one intra-molecular C-H⋯O inter-action and two H⋯H short contacts are observed, and the benzoyl and meth-oxy-methyl groups show orientational disorder.
View Article and Find Full Text PDFActa Crystallogr E Crystallogr Commun
January 2025
The title compound, [Cu(CHO)(CHN)], crystallizes in the ortho-rhom-bic space group . In the crystal structure, the Cu ion is coordinated by two acetyl-acetonate ligands and one 2-amino-1-methyl-1-benzimidazole ligand. The crystal structure features intra-molecular N-H⋯O and inter-molecular N-H⋯O hydrogen bonds, which contribute to the overall cohesion of the crystal.
View Article and Find Full Text PDFActa Crystallogr E Crystallogr Commun
January 2025
Osaka Research Institute of Industrial Science and Technology, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553, Japan.
The asymmetric unit of the title compound is composed of one host mol-ecule, -4-(1 ,5 -3-aza-1,5(3,9)-dicarbazola-cyclo-octa-phane-3-yl)benzo-nitrile and one di-chloro-methane solvate mol-ecule, CHN·CHCl. The host mol-ecule possesses a planar chirality but crystallizes as a racemate in the space group 2/. It adopts an -configuration, in which two carbazole rings are partially overlapped with a parallel orientation.
View Article and Find Full Text PDFCellular chromatin displays heterogeneous structure and dynamics, properties that control diverse nuclear processes. Models invoke phase separation of conformational ensembles of chromatin fibers as a mechanism regulating chromatin organization . Here we combine biochemistry and molecular dynamics simulations to examine, at single base-pair resolution, how nucleosome spacing controls chromatin phase separation.
View Article and Find Full Text PDFSmall
January 2025
Jiangxi Province Key Laboratory of Functional Crystalline Materials Chemistry, School of Chemistry and Chemical Engineering, Jiangxi University of Science and Technology, 156 Ke Jia Avenue, Ganzhou, 341000, P. R. China.
Incorporating a third component through ternary copolymerization strategy has proven to be a promising and effective approach for further improving the device performance of polymer donors. However, terpolymer donors typically exhibit negative effects on molecular stacking and weaken charge transport due to the irregular distribution of the polymer skeleton. Herein, two terpolymers PBBQ-5 (5% ff-Qx) and PBBQ-10 (10% ff-Qx) are developed by introducing the difluoro-2-(3-hexyldecyloxy) quinoxaline (ff-Qx) to the main chain of PM6.
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