Enzyme-substrate interactions play a crucial role in enzymatic catalysis. Quantum theory of atoms in molecules (QTAIM) calculations are extremely useful in computational studies of these interactions because they provide very detailed information about the strengths and types of molecular interactions. QTAIM also provides information about the intramolecular changes that occur in the catalytic reaction. Here, we analyze the enzyme-substrate interactions and the topological properties of the electron density in the enantioselective step of the acylation of (,)-propranolol, an aminoalcohol with therapeutic applications, catalyzed by lipase B. Eight reaction paths (four for each enantiomer) are investigated and the energies, atomic charges, hydrogen bonds, and n → π* interactions of propranolol, the catalytic triad (composed of D187, H224, and S105), and the oxyanion hole are analyzed. It is found that D187 acts as an electron density reservoir for H224, and H224 acts as an electron density reservoir for the active site of the protein. It releases electron density when the tetrahedral intermediate is formed from the Michaelis complex and receives it when the enzyme-product complex is formed. Hydrogen bonds can be grouped into noncovalent and covalent hydrogen bonds. The latter are stronger and more important for the reaction than the former. We also found weak n → π* interactions, which are characterized by QTAIM and the natural bond orbital (NBO) analysis.
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http://dx.doi.org/10.1021/acsomega.1c02559 | DOI Listing |
Langmuir
January 2025
Prof. Rashidi Laboratory of Organometallic Chemistry & Material Chemistry, Department of Chemistry, College of Science, Shiraz University, Shiraz, 7194684795, Iran.
In this study, a Pd nanoparticles@hydrogen-bonded organic framework (Pd NPs@HOF) thin film was fabricated at the toluene-water interface. The HOF was formed through the interaction of trimesic acid (TMA) and melamine (Mel) in the water phase, while Pd(0) was produced from the reduction of [PdCl(cod)] in the organic phase. The as-synthesized Pd NPs@HOF thin film was demonstrated to be an effective catalyst for the selective reduction of -nitrophenol and -nitrophenol to -aminophenol and -aminophenol.
View Article and Find Full Text PDFChem Sci
January 2025
Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University Suzhou Jiangsu 215123 China
Understanding the oxygen reduction reaction (ORR) mechanism and accurately characterizing the reaction interface are essential for improving fuel cell efficiency. We developed an active learning framework combining machine learning force fields and enhanced sampling to explore the dynamics and kinetics of the ORR on Fe-N/C using a fully explicit solvent model. Different possible reaction paths have been explored and the O adsorption process is confirmed as the rate-determining step of the ORR at the Fe-N/C-water interface, which needs to overcome a free energy barrier of 0.
View Article and Find Full Text PDFChem Sci
January 2025
School of Chemistry and Chemical Engineering, Anhui University of Technology Ma'anshan 243032 Anhui China
Organic compounds present promising options for sustainable zinc battery electrodes. Nevertheless, the electrochemical properties of current organic electrodes still lag behind those of their inorganic counterparts. In this study, nitro groups were incorporated into pyrene-4, 5, 9, 10-tetraone (PTO), resulting in an elevated discharge voltage due to their strong electron-withdrawing capabilities.
View Article and Find Full Text PDFRSC Adv
January 2025
Institute of Chemistry, Vietnam Academy of Science and Technology Hanoi Vietnam
In this paper, a series of novel quinazoline-4(3)-one-2-carbothioamide derivatives (8a-p) were designed and synthesized the Wilgerodt-Kindler reaction between 2-methylquinazoline-4-one 10 and amines using S/DMSO as the oxidizing system. Their characteristics were confirmed by IR, NMR, HRMS spectra, and their melting point. These novel derivatives (8a-p) were evaluated for their anti-inflammatory activity by inhibiting NO production in lipopolysaccharide (LPS)-activated RAW 264.
View Article and Find Full Text PDFFront Bioeng Biotechnol
January 2025
Department of Orthodontics, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, National Center for Stomatology, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology and Shanghai Research Institute of Stomatology, Research Unit of Oral and Maxillofacial Regenerative Medicine, Chinese Academy of Medical Sciences, Shanghai, China.
A one-step hydrothermal method was applied to prepare carbon dots (CDs) with superior fluorescence properties using chitosan as a carbon source. The as-prepared carbon dots were then grafted onto a sodium alginate-gelatin hydrogel film to form a fluorescent hydrogel film (FHGF), emitting at 450 nm under excitation of 350 nm light. In comparison to the CDs, the fluorescence intensity of this film was maintained over 90.
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