Study of peroxidase mechanisms by pulse radiolysis. II. Reaction of horseradish peroxidase Compound I with O2−
1974; Elsevier BV; Volume: 350; Issue: 1 Linguagem: Inglês
10.1016/0005-2744(74)90208-3
ISSN1878-1454
AutoresBenon H. J. Bielski, David A. Comstock, Arthur Haber, Phillip C. Chan,
Tópico(s)Insect and Pesticide Research
Resumo1. Sodium formate has no effect upon the absorption spectra and the rates of reaction of horseradish peroxidase (donor: H2O2 oxidoreductase, EC 1.11.1.7) and its derivative Compound I. It is a good radiation protector for horseradish peroxidase in aerated aqueous solutions. 2. The rate of formation of Compound I has been determined in a fast kinetics spectrophotometer at 335 nm. During the conversion of horseradish peroxidase to Compound I, no other intermediates are detectable in the range from 300 to 450 nm. 3. Radiation generated superoxide radicals (O2−), reduce Compound I to Compound II with a rate constant of 1.60·106 ± 0.08·106M−1·s−1. 4. A three-dimensional computer presentation (absorbance vs wavelength vs time) shows spectral changes observed after pulse irradiation of an air-saturated formate solution containing horseradish peroxidase. 5. Studies with both pulse radiolysis and γ-ray irradiation indicate that Compound II does not react with O2−.
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