Horseradish peroxidase. Complex formation with anions and hydrocyanic acid

Equilibrium binding experiments have been performed with perchlorate, chloride, and acetate in the presence of horseradish peroxidase. The binding of perchlorate and acetate appears to be like that of nitrate, at a site other than the sixth coordination position of the heme iron. Competitive experim...

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Bibliographic Details
Published in:The Journal of biological chemistry 1981-10, Vol.256 (19), p.10099-10104
Main Authors: Araiso, T, Dunford, H B
Format: Article
Language:English
Subjects:
Acetates
Anions
Armoracia lapathifolia
Chlorides
Horseradish Peroxidase - metabolism
hydrocyonic acid
Hydrogen Cyanide
Kinetics
Mathematics
Perchlorates
peroxidase
Peroxidases - metabolism
Protein Binding
Spectrophotometry
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Summary:Equilibrium binding experiments have been performed with perchlorate, chloride, and acetate in the presence of horseradish peroxidase. The binding of perchlorate and acetate appears to be like that of nitrate, at a site other than the sixth coordination position of the heme iron. Competitive experiments using both nitrate and cyanide demonstrate that two different binding sites are present on the enzyme. Chloride appears to bind at the sixth coordination position as do both fluoride and cyanide. Temperature jump experiments indicate that it is likely the nitrate anion and not undissociated nitric acid which is the binding species. Competitive stopped flow experiments indicate that the bound nitrate slows both the association rate and dissociation rate of cyanide, indicating that nitrate binds close to the sixth coordination position.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(19)68748-X