title: Interaction between the formyl group of heme a and arginine 54 in cytochrome aa(3) from Paracoccus denitrificans.
abstract: The optical spectrum of heme a is red-shifted in aa(3)-type cytochrome c oxidases compared to isolated low-spin heme A model compounds. Early spectroscopic studies indicated that this may be due to hydrogen-bonding of the formyl group of heme a to an amino acid in the close vicinity. Here we show that most of the optical spectral shift of native heme a is due to a hydrogen-bonding interaction between the formyl group and arginine-54 in subunit I of cytochrome aa(3) from Paracoccus denitrificans, and that a smaller part is due to an electrostatic interaction between the D ring propionate of heme a and arginine-474.
authors.affiliation: Helsinki Bioenergetics Group, Department of Medical Chemistry, Institute of Biomedical Sciences and Biocentrum Helsinki, P.O. Box 8, 00014 University of Helsinki, Helsinki, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Riistama
authors.forename: M I
authors.initials: MI
authors.lastname: Verkhovsky
authors.forename: L
authors.initials: L
authors.lastname: Laakkonen
authors.forename: M
authors.initials: M
authors.lastname: Wikström
authors.forename: A
authors.initials: A
authors.lastname: Puustinen
mesh_terms: D001120:Arginine / Q000737:chemistry*; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000378:metabolism*; D006418:Heme / Q000031:analogs & derivatives* / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D010231:Paracoccus denitrificans / Q000201:enzymology*; D055672:Static Electricity
chemical_list: C027728:heme a; D006418:Heme; D001120:Arginine; D003576:Electron Transport Complex IV