Copper catalyzed oxidation of ascorbate (vitamin C). Inhibitory effect of catalase, superoxide dismutase, serum proteins (ceruloplasmin, albumin, apotransferrin) and amino acids |
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| Authors: | R A L?vstad |
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| Institution: | 1. Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States;2. Department of Biochemistry, University of Saskatchewan, Saskatoon, SK, Canada;1. Malviya National Institute of Technology Jaipur, Jawahar Lal Nehru Marg, Jhalana Gram, Malviya Nagar, Jaipur, Rajasthan 302017, India;2. National Institute of Technology Silchar, NIT Road, Fakiratilla, Silchar, Assam 788010, India;1. Vilnius University, Faculty of Mathematics, Department of Computer Science, Naugarduko 24, Vilnius, Lithuania;2. Vilnius University, Faculty of Chemistry, Department of Physical Chemistry, Naugarduko 24, Vilnius, Lithuania;3. Vilnius Gediminas Technical University, Department of Mechatronics and Robotics, J. Basanaviciaus 28, Vilnius, Lithuania;4. State Research Institute Centre for Physical Sciences and Technology, Laboratory of Bio-nanotechnology, Sauletekio 3, Vilnius, Lithuania |
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| Abstract: | The inhibitory effect of catalase and superoxide dismutase on copper catalyzed oxidation of ascorbate is probably due to a binding of copper ions. Scavengers of hydroxyl ions and singlet oxygen had no effect on the ascorbate oxidation rate. Copper binding serum proteins reduced the oxidation rate; the order of effectiveness being: Ceruloplasmin greater than human albumin = bovine albumin greater than apotransferrin. The excellent protection obtained with catalase and ceruloplasmin is possibly due to a strong affinity for cuprous ions generated during the reaction. Cupric ion binding amino acids (His, Thr, Glu, Gln, Tyr) had considerably weaker protective effect than the proteins studied. Apparently they do not compete favorably with ascorbate for cupric ions. |
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