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The 2.2 Å resolution structure of the catalase‐peroxidase KatG from Synechococcus elongatus PCC7942
Author(s) -
Kamachi Saori,
Wada Kei,
Tamoi Masahiro,
Shigeoka Shigeru,
Tada Toshiji
Publication year - 2014
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 37
ISSN - 2053-230X
DOI - 10.1107/s2053230x14002052
Subject(s) - chemistry , dimer , peroxidase , protein subunit , catalase , crystallography , stereochemistry , moiety , enzyme , biochemistry , organic chemistry , gene
The crystal structure of catalase‐peroxidase from Synechococcus elongatus PCC7942 ( Se KatG) was solved by molecular replacement and refined to an R work of 16.8% and an R free of 20.6% at 2.2 Å resolution. The asymmetric unit consisted of only one subunit of the catalase‐peroxidase molecule, including a protoporphyrin IX haem moiety and two sodium ions. A typical KatG covalent adduct was formed, Met248–Tyr222–Trp94, which is a key structural element for catalase activity. The crystallographic equivalent subunit was created by a twofold symmetry operation to form the functional dimer. The overall structure of the dimer was quite similar to other KatGs. One sodium ion was located close to the proximal Trp314. The location and configuration of the proximal cation site were very similar to those of typical peroxidases such as ascorbate peroxidase. These features may provide a structural basis for the behaviour of the radical localization/delocalization during the course of the enzymatic reaction.