Marine dissolved organic matter (DOM) presents key thermodynamic properties that are not yet fully constrained. Here, we report the distribution of binding sites occupied by protons (i.e., proton affinity spectra) and parametrize the median intrinsic proton binding affinities (log ) and heterogeneities (), for DOM samples extracted from the North Atlantic. We estimate that 11.4 ± 0.6% of C atoms in the extracted marine DOM have a functional group with a binding site for ionic species. The log of the most acidic groups was larger (4.01-4.02 ± 0.02) than that observed in DOM from coastal waters (3.82 ± 0.02), while the chemical binding heterogeneity parameter increased with depth to values (= 0.666 ± 0.009) ca. 10% higher than those observed in surface open ocean or coastal samples. On the contrary, the log for the less acidic groups shows a difference between the surface (10.01 ± 0.08) and deep (9.22 ± 0.35) samples. The latter chemical groups were more heterogeneous for marine than for terrestrial DOM, and decreased with depth to values of 0.28 ± 0.03. Binding heterogeneity reflects aromatic carbon compounds' persistence and accumulation in diverse, low-abundance chemical forms, while easily degradable low-affinity groups accumulate more uniformly in the deep ocean.
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http://dx.doi.org/10.1021/acs.est.3c01810 | DOI Listing |
Signal Transduct Target Ther
December 2024
Department of Orthopedic Surgery/Sports Medicine Center, Southwest Hospital, Army Medical University, Chongqing, 400038, China.
Metabolites can double as a signaling modality that initiates physiological adaptations. Metabolism, a chemical language encoding biological information, has been recognized as a powerful principle directing inflammatory responses. Cytosolic pH is a regulator of inflammatory response in macrophages.
View Article and Find Full Text PDFFEBS Lett
December 2024
Department of Biochemistry and Molecular Biology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Israel.
The Homo sapiens Na/H antiporter NHA2 (SLC9B2) transports Na or Li in exchange for protons across cell membranes, and its dysfunction results in various pathologies. The activity of HsNHA2 is specifically inhibited by the flavonoid phloretin. Using bioinformatic modeling, we predicted two amino acids (R177 and S178) as being important for the binding of phloretin to the HsNHA2 molecule.
View Article and Find Full Text PDFProtein Sci
January 2025
Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biochemistry, University of Verona, Verona, Italy.
Human succinic semialdehyde dehydrogenase is a mitochondrial enzyme fundamental in the neurotransmitter γ-aminobutyric acid catabolism. It catalyzes the NAD-dependent oxidative degradation of its derivative, succinic semialdehyde, to succinic acid. Mutations in its gene lead to an inherited neurometabolic rare disease, succinic semialdehyde dehydrogenase deficiency, characterized by mental and developmental delay.
View Article and Find Full Text PDFMembranes (Basel)
December 2024
Laboratório de Ciências Físicas, Centro de Ciência e Tecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes 28013-602, RJ, Brazil.
Phase separation is essential for membrane function, and alterations in phase coexistence by membrane-interacting molecules, such as nicotine, can impair membrane stability. With the increasing use of e-cigarettes, concerns have arisen about the impact of nicotine on pulmonary surfactants. Here, we used differential scanning calorimetry (DSC), molecular dynamics (MD) simulations, and electron spin resonance (ESR) to examine nicotine's effect on the phase coexistence of two surfactant models: pure DPPC and a DPPC/POPC/POPG mixture.
View Article and Find Full Text PDFPhytomedicine
December 2024
College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, PR China; Ministry of Education Key Laboratory for Animal Pathogens and Biosafety, Zhengzhou, Henan Province, PR China; Henan Province Key Laboratory of Animal Food Pathogens SurveillancePR China. Electronic address:
Background: Tigecycline is one of the few effective treatments for multidrug-resistant bacteria. However, the recent emergence and spread of high-level tigecycline resistance in Enterobacteriaceae have significantly limited its clinical use. To combat this challenge, combining antibiotics with adjuvants has emerged as a promising strategy.
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