Use of polyaminocarboxylates as metal chelators.
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Carboxylic Acids↗
Biomedical subjects
D E Cabelli
Publications and source records attributed to D E Cabelli.
The interaction between Cu(I) superoxide dismutase and hydrogen peroxide.
The interaction between superoxide dismutase (SOD) and peroxide, under anaerobic conditions in the presence of an OH radical scavenger, formate, and an indicator, nitro blue tetrazolium, involves five reactions and an equilibrium: (table; see text) Reaction 3 occurs at a rate that is proportional to both peroxide and enzyme with no kinetic evidence for any intermediate peroxide-enzyme complex. Rate studies as a function of pH corroborate previously published work (Fuchs, H. J. R., and Borders, C. L., Jr. (1983) Biochem Biophys. Res. Commun. 116, 1107-1113; Blech, D. M., and Borders, C. L., Jr. (1983) Arch. Biochem. Biophys. 224, 579-586) suggesting that HO2-, and not H2O2, is the active species in this system: k(HO2- + superoxide dismutase-Cu+) = 2.6 x 10(3) M-1 s-1. Evidence is presented which suggests that HO2-, like O2-, reacts at rates that are affected by the electrostatic forces of the enzyme.
Hydrogen Peroxide↗
The interactions between MnO2+/Mn3+ complexes and ascorbates. A pulse radiolysis study.
The reactivity between various MnO2+/Mn3+ complexes and ascorbic acid/ascorbate were studied using pulse radiolysis. Experimental results indicate that Mn3+-sulfate reacts with both AH2/AH- via metal-ascorbate complexes. MnO2+-formate and Mn3+-pyrophosphate both appear to react by electron transfer with no evidence of complex formation. All of these metal complexes, with the exception of Mn3+-pyrophosphate, react as fast or faster with ascorbate than free O2-. The significance of this observation in light of metal-induced oxygen toxicity will be discussed.
Ascorbic Acid↗
Studies of the reactivity of trolox with Mn3+/Fe3+ complexes by pulse radiolysis.
The rates and mechanisms for the reactions between Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), a synthetic analogue of alpha-tocopherol, Br2- and Mn3+-phosphate were determined under aerobic and anaerobic conditions by fast kinetic methods. In addition, the reaction between Fe(OH)2+ and Trolox at pH 6.0 was shown not to occur under the conditions of the experiment, leading to a limiting rate for that reaction of k less than 10(3) M-1 s-1. These results are compared to studies of the reactivity of Trolox with HO2/O2- and are discussed in light of the known antioxidant properties of vitamin E.
Benzopyrans↗
Reevaluation of the reactivity of hydroxylamine with O2-/HO2.
The reactivity of hydroxylamine with HO2/O2- radicals was studied by pulse radiolysis and stopped-flow photolysis over a pH range of 1.1-10.5. Upper limits for the rate of reaction indicate that hydroxylamine, if it reacts at all, reacts at a very slow rate. Its use as an indicator for O-2 and an assay for superoxide dismutase is, therefore, inappropriate.
Chemical Phenomena↗