Critical Comparison of the Superoxide Dismutase-like Activity of Carbon Antioxidant Nanozymes by Direct Superoxide Consumption Kinetic Measurements
| Autor: | James M. Tour, Ah-Lim Tsai, Thomas A. Kent, Trenton Roy, Gang Wu, Vladimir Berka, Kimberly Mendoza, Paul J. Derry, Eugenia Kakadiaris |
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| Rok vydání: | 2019 |
| Předmět: |
Fullerene
Inorganic chemistry General Physics and Astronomy 02 engineering and technology 010402 general chemistry 01 natural sciences Antioxidants Catalysis Article Nanocomposites Polyethylene Glycols law.invention Superoxide dismutase chemistry.chemical_compound Reaction rate constant Superoxides law General Materials Science Electron paramagnetic resonance biology Superoxide Dismutase Superoxide technology industry and agriculture General Engineering Substrate (chemistry) 021001 nanoscience & nanotechnology Carbon 0104 chemical sciences Kinetics chemistry Yield (chemistry) biology.protein Graphite Fullerenes 0210 nano-technology Hydrophobic and Hydrophilic Interactions |
| Zdroj: | ACS Nano |
| ISSN: | 1936-086X 1936-0851 |
| DOI: | 10.1021/acsnano.9b04229 |
| Popis: | The superoxide dismutase-like activity of poly(ethylene-glycolated) hydrophilic carbon clusters (PEG-HCCs), anthracite and bituminous graphene quantum dots (PEG-aGQDs and PEG-bGQDs, respectively), and two fullerene carbon nanozymes, tris malonyl-C(60) fullerene (C3) and polyhydroxylated-C(60) fullerene (C(60)-OH(n)), were compared using direct optical stopped-flow kinetic measurements, together with three native superoxide dismutases (SODs), CuZnSOD, MnSOD, and FeSOD at both pH 12.7 and 8.5. Computer modeling including both SOD catalytic steps and superoxide self-dismutation enabled the best choice of catalyst concentration with minimal contribution to the observed kinetic change from the substrate self-dismutation. Bi-exponential fitting to the kinetic data ranks the rate constant (M(−1) s(−1)) in the order of: PEG-HCCs > CuZnSOD ≈ MnSOD ≈ PEG-aGQDs ≈ PEG-bGQDs > FeSOD >> C3 > C(60)-OH(n) at pH 12.7, and MnSOD > CuZnSOD ≈ PEG-HCCs > FeSOD > PEG-aGQDs ≈ PEG-bGQDs >> C3 ≈ C(60)-OH(n) at pH 8.5. Nonlinear regression of the kinetic model above yielded the same ranking as bi-exponential fit, but provided better mechanistic insight. The data obtained by freeze-quench EPR direct assay at pH 12.7 also yields the same ranking as stopped-flow data. This is a necessary assessment of a panel of proclaimed carbon nano SOD mimetics using the same two direct methods, revealing a dramatic, 3 – 4 order of magnitude difference in SOD activity between PEG-HCCs/PEG-GQDs from soluble fullerenes. |
| Databáze: | OpenAIRE |
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