An Electrical Potential in the Access Channel of Catalases Enhances Catalysis
Open Access
- 1 August 2003
- journal article
- Published by Elsevier BV
- Vol. 278 (33), 31290-31296
- https://doi.org/10.1074/jbc.m304076200
Abstract
Substrate H2O2 must gain access to the deeply buried active site of catalases through channels of 30–50 Å in length. The most prominent or main channel approaches the active site perpendicular to the plane of the heme and contains a number of residues that are conserved in all catalases. Changes in Val169, 8 Å from the heme in catalase HPII from Escherichia coli, introducing smaller, larger or polar side chains reduces the catalase activity. Changes in Asp181, 12 Å from the heme, reduces activity by up to 90% if the negatively charged side chain is removed when Ala, Gln, Ser, Asn, or Ile are the substituted residues. Only the D181E variant retains wild type activity. Determination of the crystal structures of the Glu181, Ala181, Ser181, and Gln181 variants of HPII reveals lower water occupancy in the main channel of the less active variants, particularly at the position forming the sixth ligand to the heme iron and in the hydrophobic, constricted region adjacent to Val169. It is proposed that an electrical potential exists between the negatively charged aspartate (or glutamate) side chain at position 181 and the positively charged heme iron 12 Å distant. The potential field acts upon the electrical dipoles of water generating a common orientation that favors hydrogen bond formation and promotes interaction with the heme iron. Substrate hydrogen peroxide would be affected similarly and would enter the active site oriented optimally for interaction with active site residues.Keywords
This publication has 36 references indexed in Scilit:
- Active and inhibited human catalase structures: ligand and NADPH binding and catalytic mechanism 1 1Edited by R. HuberJournal of Molecular Biology, 2000
- Structure of catalase-A from Saccharomyces cerevisiaeJournal of Molecular Biology, 1999
- Refinement of Macromolecular Structures by the Maximum-Likelihood MethodActa Crystallographica Section D-Biological Crystallography, 1997
- [20] Processing of X-ray diffraction data collected in oscillation modeMethods in Enzymology, 1997
- Crystal Structure ofProteus mirabilisPR Catalase With and Without Bound NADPHJournal of Molecular Biology, 1995
- SETOR: Hardware-lighted three-dimensional solid model representations of macromoleculesJournal of Molecular Graphics, 1993
- Three‐dimensional structure of catalase from Micrococcus lysodeikticus at 1.5 Å resolutionFEBS Letters, 1992
- The refined structure of beef liver catalase at 2·5 Å resolutionActa crystallographica Section B, Structural science, crystal engineering and materials, 1986
- Improved M13 phage cloning vectors and host strains: nucleotide sequences of the M13mpl8 and pUC19 vectorsGene, 1985
- Structure of beef liver catalaseJournal of Molecular Biology, 1981