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The active site structure of E. coli HPII catalase
Author(s) -
Dawson John H.,
Bracete Alma M.,
Huff Ann M.,
Kadkhodayan Saloumeh,
Zeitler Caroline M.,
Sono Masanori,
Chang Chi K.,
Loewen Peter C.
Publication year - 1991
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(91)81401-s
Subject(s) - chlorin , heme , chemistry , catalase , ligand (biochemistry) , histidine , myoglobin , ferric , horseradish peroxidase , peroxidase , metalloprotein , stereochemistry , circular dichroism , photochemistry , biochemistry , porphyrin , enzyme , inorganic chemistry , receptor
E. coli produces 2 catalases known as HPI and HPII. While the heme prosthetic group of the HPII catalase has been established to be a dihydroporphyrin or chlorin, the identity of the proximal ligand to the iron has not been addressed. The magnetic circular dichroism (MCD) spectrum of native ferric HPII catalase is very similar to those of a 5‐coordinate phenolate‐ligated ferric chlorin complex, a model for tyrosinate proximal ligation, as well as of chlorin‐reconstituted ferric horseradish peroxidase, a model for 5‐coordinate histidine ligation. However, further MCD comparisons of chlorin‐reconstituted myoglobin with parallel ligand‐bound adducts of the catalase clearly rule out histidine ligation in the latter, leaving tyrosinate as the best candidate for the proximal ligand.