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Insertion of an H-bonding residue into the distal pocket of the ferriheme protein nitrophorin 4: effect on nitrite-iron coordination and nitrite disproportionation.
- Source :
-
Chemistry & biodiversity [Chem Biodivers] 2012 Sep; Vol. 9 (9), pp. 1761-75. - Publication Year :
- 2012
-
Abstract
- Heme proteins are important entities for the metabolism of nitrite. Inspection of the structural features of the reported hemoprotein-nitrite crystal structures reveals that, except for nitrophorin 4 (NP4), H-bonding to the nitrite ligand is accomplished via histidine or arginine residues. These H-bonds probably play an important role for the nitrite coordination and/or reactivities. In nitrophorins, which catalyze the nitrite disproportionation reaction, such a residue is missing. Here, we report on the L130R mutant of the NP isoprotein NP4 that provides the Arg130 residue as part of the flexible G-H loop as a potential H-bonding residue in the distal heme pocket. Similar to the wild-type protein, nitrite remains N-bonded in the crystal structure of NP4(L130R). However, spectroscopic investigations show that, in solution, a second ligand-rotational orientation exists, which is in fast-exchange equilibrium with the normal, parallel ligand orientation. Moreover, the nitrite disproportionation is inhibited in NP4(L130R). Comparison with another, also less active mutant NP4(D30N) suggests that the displacement of H(2)O molecules from the heme cavity prevents the proton donation pathway through Asp30.<br /> (Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich.)
- Subjects :
- Binding Sites
Crystallography, X-Ray
Hemeproteins genetics
Hemeproteins metabolism
Hydrogen Bonding
Magnetic Resonance Spectroscopy
Models, Molecular
Mutation
Salivary Proteins and Peptides genetics
Salivary Proteins and Peptides metabolism
Hemeproteins chemistry
Hemin chemistry
Iron chemistry
Nitrites chemistry
Salivary Proteins and Peptides chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1612-1880
- Volume :
- 9
- Issue :
- 9
- Database :
- MEDLINE
- Journal :
- Chemistry & biodiversity
- Publication Type :
- Academic Journal
- Accession number :
- 22976968
- Full Text :
- https://doi.org/10.1002/cbdv.201100401