The Heme Environment of Ovoperoxidase as Determined by Optical Spectroscopy

Native ovoperoxidase exhibited an optical absorption spectrum with certain similarities to lactoperoxidase, but not horseradish peroxidase, over the pH range 4.5–11.5. Ovoperoxidase had three distinct spectral forms dependent on pH, with transitions at apparent pKa values of 6.6 and 3.0. Complexes o...

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Published in:The Journal of biological chemistry 1989-10, Vol.264 (29), p.17231-17235
Main Authors: Somers, C E, Shapiro, B M
Format: Article
Language:English
Subjects:
Analytical, structural and metabolic biochemistry
Animals
Anions
Azides - metabolism
Biological and medical sciences
Cyanides - metabolism
Enzymes and enzyme inhibitors
Female
Fluorides - metabolism
Fundamental and applied biological sciences. Psychology
Galectins
Hemagglutinins - genetics
Heme
Horseradish Peroxidase
Hydrogen-Ion Concentration
Lactoperoxidase
Ovum - enzymology
Oxidation-Reduction
Oxidoreductases
Peroxidases
Sea Urchins - enzymology
Spectrophotometry
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Summary:Native ovoperoxidase exhibited an optical absorption spectrum with certain similarities to lactoperoxidase, but not horseradish peroxidase, over the pH range 4.5–11.5. Ovoperoxidase had three distinct spectral forms dependent on pH, with transitions at apparent pKa values of 6.6 and 3.0. Complexes of ovoperoxidase with CN−, N3−, F−, or when reduced and ligated to carbon monoxide, CN−, or pyridine, were distinct from other peroxidases. Ovoperoxidase formed two specific and different spectral derivatives at pH 6.0 and 8.0, either in the native state, or when combined with CN−, when reduced, or when reduced and ligated to CN−. The position of the Soret band when mixed with near-stoichiometric amounts of H2O2. This cycling was inhibited by Phenylhydrazine, 3-amino-1,2,4-triazole, or low pH (≤6). Compound II was formed when ovoperoxidase was mixed with ethyl hydrogen peroxide in a 1:3 ratio, but not with H2O2. With a great excess of H2O2, Compound III was formed at pH 8.0; at pH 6.0 or below, the Soret band shifted slightly with excess of H2O2, but Compound III was never formed. Even when ovoperoxidase was bound to proteoliaisin (Weidman, P. J., and Shapiro, B. M. (1987) J. Cell Biol. 105, 561–567), ovoperoxidase exhibited spectral characteristics of the free enzyme.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)71482-8