A kinetic analysis of the mechanism of autocatalytic activation in the presence of a reversible inhibitor is presented. The kinetic equations of both the transient phase and the steady state are derived for this mechanism. We have extended the kinetic equations derived to a particular case in rapid equilibrium conditions. This analysis is illustrated by the experimental study of the inhibition by p-aminobenzamidine of trypsin activity in its action on trypsinogen. In such system, the amount of active enzyme increases exponentially, as expected from an autocatalytic process. The results obtained show that the apparent activation rate constant decreases non-linearly with the initial concentration of inhibitor, according to the equations obtained in the kinetic analysis.
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http://dx.doi.org/10.1515/bchm3.1995.376.9.577 | DOI Listing |
J Am Chem Soc
January 2025
Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States.
Hydrogen atom transfer (HAT) reactions and their kinetic barriers Δ are important in organic and inorganic chemistry. This study examines factors that influence Δ, reporting the kinetics and thermodynamics of HAT from various ruthenium bis(acetylacetonate) pyridine-imidazole complexes to nitroxyl radicals. Across these 36 reactions, the Δ and Δ can be independently varied, with different sets of Ru complexes primarily tuning either their ps or their °s.
View Article and Find Full Text PDFJ Mol Model
January 2025
College of Chemical Engineering, Fuzhou University, Fuzhou, 350116, People's Republic of China.
Context: The rotating arc plasma technique for the synthesis of nitrogen-doped graphene capitalizes on the distinctive attributes of plasma, presenting a straightforward, efficient, and catalyst-free strategy for the production of nitrogen-doped graphene. However, experimental outcomes generally fail to elucidate the atomic-level mechanism behind this process. Our research utilizes molecular dynamics simulations to explore theoretically the formation of radicals during the plasma-driven reaction between methane (CH₄) and nitrogen (N₂).
View Article and Find Full Text PDFClin Nucl Med
January 2025
From the Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva, Switzerland.
Purpose: The common approach for organ segmentation in hybrid imaging relies on coregistered CT (CTAC) images. This method, however, presents several limitations in real clinical workflows where mismatch between PET and CT images are very common. Moreover, low-dose CTAC images have poor quality, thus challenging the segmentation task.
View Article and Find Full Text PDFNucleic Acids Res
January 2025
Department of Medicine, UofL Health Brown Cancer Center, University of Louisville, Louisville KY, 505 S Hancock St, Louisville, KY 40202, United States.
Time-resolved small-angle X-ray experiments are reported here that capture and quantify a previously unknown rapid collapse of the unfolded oligonucleotide as an early step in the folding of hybrid 1 and hybrid 2 telomeric G-quadruplex structures. The rapid collapse, initiated by a pH jump, is characterized by an exponential decrease in the radius of gyration from 24.3 to 12.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal, Telangana 506004, India.
We report nonconjugated monocyclic dienes (nCMDs) as unique photoswitchable molecules that hold promise for harvesting substantial solar energy and storing it for extended durations. Herein, cyclohepta-1,4-diene and its N-heterocyclic analogue have been considered as prototypical models for investigating photoswitching behavior in nCMDs. Initially, the nonradiative deactivation pathway of nCMD from the low-lying excited state to the [2 + 2]-cycloadduct has been evaluated.
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