The binding of ethyl isocyanide to ferroperoxidase.
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ABSTRACT: The equilibrium and kinetics of ethyl isocyanide binding to ferroperoxidase were studied. At pH9.1 the results of both studies are consistent with a single-process model with an affinity constant of 95m(-1) and combination and dissociation constants of 2.2x10(3)m(-1).s(-1) and 23s(-1) respectively. Ethyl isocyanide is not bound significantly at pH values lower than 6.0, and in this behaviour and the pH-dependence of the affinity constant, similarities exist between isocyanide and cyanide binding. The enthalpy of the process measured by equilibrium methods is -59kJ/mol (-14kcal/mol). At pH values below 9, the ethyl isocyanide adduct changes in a slow time-dependent manner, giving rise to a new species. These changes are reversible on increasing the pH. The results are discussed in relation to other known information about ligand binding to ferroperoxidase and to myoglobin.
SUBMITTER: Phelps C
PROVIDER: S-EPMC1173773 | biostudies-other | 1972 Jun
REPOSITORIES: biostudies-other
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