Zobrazení zdroje stránky Henriksenlanier0765

The formation of purine and pyrimidine base pairs (BPs), which contributes to shaping of the canonical and noncanonical 3D structures of nucleic acids, is one the most investigated phenomena in chemistry and life sciences. In this contribution, the anatomy of the bond energy (BDE) of the base-pairing interaction in 39 different arrangements found experimentally or predicted for DNA structures containing the four common nucleobases (A, C, G, T) in their neutral or protonated forms is described in light of the theory of interacting quantum atoms within the context of the quantum theory of atoms in molecules. The interplay of individual energy components involved in the three stages of the bond formation process (structural deformation, electron-density promotion, and intermolecular interaction) is studied. We recognized that for the neutral BPs, variations in the kinetic and electrostatic contributions to the BDE are rather negligible, leaving the exchange-correlation energy as the main stabilizing component. It is shown that the contribution of the exchange-correlation term can be recovered by including atoms that are formally assumed to be hydrogen bonded (primary interaction). In contrast, to recover the electrostatic component of interaction, one must consider both the primary and secondary (formally nonbonded atoms) interatomic interactions. The results of our study were employed to design new types of BPs with altered bonding anatomy. [https://www.selleckchem.com/products/sy-5609.html selleckchem] We demonstrate that improving the electrostatic characteristics of the BPs does not necessarily result in greater interaction energies if weak secondary hydrogen bonding is destroyed. However, the main tuning factor for systems with conserved interacting faces (primary interactions) is the electrostatic component of the interaction energy resulting from the secondary atom-atom electrostatics.Genomic DNA is chemically reactive and therefore susceptible to damage by many exogenous and endogenous sources. Lesions produced from these damaging events can have various mutagenic and genotoxic consequences. This Perspective follows the journey of one particular lesion, 1,N6-ethenoadenine (εA), from its formation to replication and repair, and its role in cancerous tissues and inflammatory diseases. εA is generated by the reaction of adenine (A) with vinyl chloride or lipid peroxidation products. We present the miscoding properties of εA with an emphasis on how bacterial and mammalian cells can process lesions differently, leading to varied mutational spectra. But with information from these assays, we can better understand how the miscoding properties of εA lead to biological consequences and how genomic stability can be maintained via DNA repair mechanisms. We discuss how base excision repair (BER) and direct reversal repair (DRR) can minimize the biological consequences of εA lesions. Kinetic parameters of glycosylases and AlkB family enzymes are described, along with a discussion of the relative contributions of the BER and DRR pathways in the repair of εA. Because eukaryotic DNA is packaged in chromatin, we also discuss the impact of this packaging on BER and DRR, specifically in regards to repair of εA. Studying DNA lesions like εA in this context, from origin to biological implications, can provide crucial information to better understand prevention of mutagenesis and cancer.Organic mixed ionic-electronic conductors (OMIECs) are an emerging family of materials crucial in the development of flexible, bio-, and optoelectronics. In electrochromic polymers, the cyclic redox reaction is associated with a mechanical breathing strain, which deforms the OMIECs and degrades the device reliability. We set forth an in situ nanoindentation approach to measure the breathing strain of a poly(3,4-propylenedioxythiophene) (PProDOT) thin film in a customized liquid cell during electrochromic cycles. A breathing volumetric strain of 12-25% is persistent in different sets of electrolytes of various solvents, salts, and salt molarities. The electrochemical conditioning, intermittence time, and cyclic protocol have minor effects on the mechanical response of PProDOT. The mechanical behavior and anion diffusivity measurement further infer the redox kinetics. Heavily cycled PProDOT films show reduced volumetric strain and accumulated mechanical damage of channel cracks and dysfunctional regions of slow and inhomogeneous electrochromic switching. This work is a systematic characterization of mechanical deformation and damage in a model OMIEC and informs the mechanical reliability of organic electrochromic devices.Over 100 nations signed the Minamata Convention on Mercury to control the adverse effects of mercury (Hg) emissions on human beings. A spatially explicit analysis is needed to identify the specific sources and distribution of Hg-related health impacts. This study maps China's Hg-related health impacts and global supply chain drivers (i.e., global final consumers and primary suppliers) at a high spatial resolution. Here we show significant spatial heterogeneity in hotspots of China's Hg-related health impacts. Approximately 1% of the land area holds only 40% of the Chinese population but nearly 70% of the fatal heart attack deaths in China. Moreover, approximately 3% of the land area holds nearly 60% of the population but 70% of the intelligence quotient (IQ) decrements. The distribution of hotspots of China's Hg-related health impacts and global supply chain drivers are influenced by various factors including population, economy, transportation, resources, and dietary intake habits. These spatially explicit hotspots can support more effective policies in various stages of the global supply chains and more effective international cooperation to reduce Hg-related health impacts. This can facilitate the successful implementation of the Minamata Convention on Mercury.The photoinduced reactions of tetraphenyldiphosphine disulfide with a range of organic dichalcogenides successfully afforded a series of phosphorus(V)-chalcogen interelement compounds via a radical process. The relative reactivities of the organic dichalcogenides (i.e., (PhS)2, (PhSe)2, and (PhTe)2) toward the PIII or PV groups in the diphosphine analogues under light were investigated in detail, and a convenient method was developed to form P-S or P-Se interelement compounds from tetraphenyldiphosphine disulfide and (PhS)2 or (PhSe)2 upon photoirradiation. Furthermore, the relative photochemical properties and reactivities of tetraphenyldiphophine (P-P interelement compound) and its analogues toward photoinduced radical addition reactions were also discussed. The formed P-E (E = S, Se) interelement compounds could be utilized for ionic reactions, and they could be transformed into various phosphine reagents via one-pot processes.