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Heme‐linked ionization and ligand binding produce identical changes of proximal heme stereochemistry in reduced horseradish peroxidase Evidence for existence of two protein conformations
Author(s) -
Sharonov Yurii A.,
Pismensky Victor F.,
Yarmola Elena G.
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)81234-1
Subject(s) - horseradish peroxidase , heme , chemistry , ligand (biochemistry) , peroxidase , hemeprotein , stereochemistry , biochemistry , enzyme , receptor
The visible and near infrared magnetic circular dichroism spectra of chemically reduced horseradish peroxidase at neutral and alkaline pH values and 5‐coordinate protoheme‐(2‐methylimidazole) at pH 9.1 were compared at 4.2 K with those of photolysis products of their carbon monoxide complexes. From the results obtained we concluded that: (i) there are two protein conformations of HRP which determine the geometry of the Fe‐N(His) bond; (ii) the transition from one conformation (heme stereochemistry) to another can be induced by either heme‐linked ionization or ligand binding; (iii) a trigger mechanism for switching between two conformations has to exist.