Electron paramagnetic resonance (EPR) spectroscopy has been used to study the metal coordination sphere geometry in the cobalt-substituted Zn-protein angiotensin I-converting enzyme (ACE). It has been shown that ACE contains two distinct metal-binding sites. In the presence of the two structurally different inhibitors, captopril and ramiprilat, it is found that the metal binding sites are nearly structurally identical and are separated more than 10 A from each other. The metal atoms are most likely four- to five-coordinated, and it is argued that the inhibitor binds directly to the metal ion.
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http://dx.doi.org/10.1016/0162-0134(95)00143-3 | DOI Listing |
Magn Reson Chem
January 2025
School of Chemistry and Environmental Science, Shangrao Normal University, Shangrao, Jiangxi, China.
The defect structures of the orthorhombical and tetragonal Cu centers in CuHZr(PO) are theoretically studied by analyzing their experimental electron paramagnetic resonance (EPR) parameters, based on the perturbation formulas of these parameters for a 3d ion in orthorhombically and tetragonally elongated octahedra, respectively. The above centers are attributed to the Cu ions locating at M(1) site, and the crystal field parameters (CFPs) are quantitatively determined from the superposition model and the local structures of the Cu sites. Based on the calculation, the parallel Cu-O bonds may undergo the relative elongations ΔZ (≈ 0.
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
Felix Bloch Institute for Solid State Physics, Leipzig University, Leipzig, Germany.
Electron paramagnetic resonance (EPR) spectroscopy is a powerful method to characterize the local framework structure of nanoporous materials during the dihydrogen isotopologue adsorption process. It also allows for exploring the adsorption sites of the dihydrogen isotopes and monitoring their desorption characteristics on the microscopic scale. The paramagnetic spin probes in the form of transition metal ions or organic radicals are required for EPR spectroscopy and are introduced either at the framework lattice position or in the pores of the metal-organic frameworks.
View Article and Find Full Text PDFJ Mater Chem B
January 2025
Division of Biophotonics and Imaging, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST), Trivandrum 695012, India.
Targeting the unique characteristics of the tumor microenvironment (TME) has emerged as a highly promising strategy for cancer therapy. Chemodynamic therapy (CDT), which leverages the TME's intrinsic properties to convert HO into cytotoxic hydroxyl radicals (˙OH), has attracted significant attention. However, the effectiveness of CDT is often limited by the catalytic efficiency of the materials used.
View Article and Find Full Text PDFJACS Au
January 2025
Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India.
Numerous attempts for organic radical stability mostly entail steric hindrance, spin-delocalization, supramolecular interaction with the host, π-π interactions, and hydrogen bonding. To date, there is no report of single crystals containing a hydroxyl radical (OH). In this work, we have stabilized OH in the crystal, which has been obtained from the filtrate after separating the precipitate of the chromenopyridine radical (DCP(2)) from the reaction mixture.
View Article and Find Full Text PDFChem Biomed Imaging
January 2025
In Vivo Multifunctional Magnetic Resonance Center, Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, West Virginia 26506, United States.
Enzyme catalytic activities are critical biomarkers of tissue states under physiological and pathophysiological conditions. However, the direct measurement and imaging of enzyme activity remains extremely challenging. We report the synthesis and characterization of the first stable triarylmethyl (TAM) radical substrate of alkaline phosphatase (TAM-ALPs).
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