57.
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Proton and copper (Cu) binding to soil and lignite-based humic acid (HA) was investigated by combining X-ray absorption fine structure (XAFS) spectroscopy, isothermal titration calorimetry (ITC), and nonideal-competitive-adsorption (NICA) modeling. NICA model calculations and XAFS results showed that bidentate and monodentate complexation occurred for Cu binding to HA. The site-type-specific thermodynamic parameters obtained by combining ITC measurements and NICA calculations revealed that copper binding to deprotonated carboxylic-type sites was entropically driven and that to deprotonated phenolic-type sites was driven by entropy and enthalpy. Copper binding to HA largely depended on the site-type and coordination environment, but the thermodynamic binding mechanisms for Cu binding to the specific site-types were similar for the different HAs studied. By comparing the site-type-specific thermodynamic parameters of HA-Cu complexation with those of low molar mass organic acids, the Cu coordination could be further specified. Bidentate carboxylic-Cu complexes made the dominating contributions to Cu binding to HA. The present study not only yields molecular-scale mechanisms of ion binding to carboxylic- and phenolic-type sites of HA but also provides the new insight that the universal nature of site-type-specific thermodynamic data enables quantitative estimation of the binding structures of heavy metal ions to humic substances.
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http://dx.doi.org/10.1021/acs.est.7b06281 | DOI Listing |
Molecules
January 2025
Department of Chemistry & Biochemistry, Miami University, Oxford, OH 45056, USA.
Epigallocatechin gallate (EGCg), an abundant phytochemical in green tea, is an antioxidant that also binds proteins and complex metals. After gastrointestinal absorption, EGCg binds to serum albumin in the hydrophobic pocket between domains IIA and IIIA and overlaps with the Sudlow I site. Serum albumin also has two metal binding sites, a high-affinity N-terminal site (NTS) site that selectively binds Cu(II), and a low-affinity, less selective multi-metal binding site (MBS).
View Article and Find Full Text PDFBiomolecules
January 2025
Department of Chemistry and Institute of Nanotechnology and Advanced Materials, Faculty of Exact Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel.
Ctr1 is a membrane-spanning homotrimer that facilitates copper uptake in eukaryotic cells with high affinity. While structural details of the transmembrane domain of human Ctr1 have been elucidated using X-ray crystallography and cryo-EM, the transfer mechanisms of copper and the conformational changes that control the gating mechanism remain poorly understood. The role of the extracellular N-terminal domains is particularly unclear due to the absence of a high-resolution structure of the full-length hCtr1 protein and limited biochemical and biophysical characterization of the transporter in solution and in cell.
View Article and Find Full Text PDFAnimals (Basel)
January 2025
Key Laboratory of Efficient Utilization of Non-Grain Feed Resources (Co-Construction by Ministry and Province), Ministry of Agriculture and Rural Affairs, Shandong Provincial Key Laboratory of Animal Nutrition and Efficient Feeding, Department of Animal Science and Technology, Shandong Agricultural University, Tai'an 271017, China.
The objective of this study was to explore the effects of dietary iron (Fe) levels on the production performance, nutrient digestibility, blood biochemistry, and meat and fur quality of growing Rex rabbits. Two hundred 3-month-old Rex rabbits were randomly allocated to five groups, each with forty replicates. Rabbits were fed a basal diet supplemented with varying levels of Fe (0, 20, 40, 80, and 160 mg/kg) in the form of ferrous sulfate monohydrate.
View Article and Find Full Text PDFPhysiol Plant
January 2025
Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.
Salt stress disturbs plant growth and photosynthesis due to its toxicity. The ice plant Mesembryanthemum crystallinum is a highly salt-tolerant facultative crassulacean acid metabolism (CAM) plant. However, the genetic basis of the salt tolerance mechanisms in ice plants remains unclear.
View Article and Find Full Text PDFChem Biol Interact
January 2025
Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece. Electronic address:
Gliomas constitute the most prevalent primary central nervous system tumors, often characterized by complex metabolic profile, genomic instability, and aggressiveness, leading to frequent relapse and high mortality rates. Traditional treatments are commonly ineffective because of gliomas increased heterogeneity, invasive characteristics and resistance to chemotherapy. Among several pathways affecting cellular homeostasis, cuproptosis has recently emerged as a novel type of programmed cell death, triggered by accumulation of copper ions.
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