Journal article
Rearrangement of the distal pocket accompanying E7 His->Gln substitution in elephant carbonmonoxy- and oxymyoglobin: proton NMR identification of a new aromatic residue in the heme pocket
Biochemistry (Easton), Vol.29(10), pp.2578-2585
03/01/1990
DOI: 10.1021/bi00462a021
Abstract
Two-dimensional 1H NMR methods have been used to assign side-chain resonances for the residues in the distal heme pocket of elephant carbonmonoxymyoglobin (MbCO) and oxymyoglobin (MbO2). It is shown that, while the other residues in the heme pocket are minimally perturbed, the Phe CD4 residue in elephant MbCO and MbO2 resonates considerbly upfield compared to the corresponding residue in sperm whale MbCO. The new NOE connectivities to Val El 1 and heme-induced ring current calculations indicate that Phe CD4 has been inserted into the distal heme pocket by reorienting the aromatic side chain and moving the CD corner closer to the heme. The C? H proton of the Phe CD4 was found to move toward the iron of the heme by ~4 Å relative to the position in sperm whale MbCO, requiring minimally a 3-Å movement of the CD helical backbone. The significantly altered distal conformation in elephant myoglobin, rather than the single distal E7 substitution, forms a plausible basis for its altered functional properties of lower autoxidation rate, higher redox potential, and increased affinity for CO ligand. These results demonstrate that one-to-one interpretation of amino acid residue substitution (E7 His ? G1n) is oversimplified and that conformational changes of substituted proteins which are not readily predicted have to be considered for interpretation of their functional properties.
Details
- Title: Subtitle
- Rearrangement of the distal pocket accompanying E7 His->Gln substitution in elephant carbonmonoxy- and oxymyoglobin: proton NMR identification of a new aromatic residue in the heme pocket
- Creators
- Liping P Yu - University of California, DavisGerd N La MarHiroshi Mizukami
- Resource Type
- Journal article
- Publication Details
- Biochemistry (Easton), Vol.29(10), pp.2578-2585
- Publisher
- American Chemical Society
- DOI
- 10.1021/bi00462a021
- ISSN
- 0006-2960
- eISSN
- 1520-4995
- Language
- English
- Date published
- 03/01/1990
- Academic Unit
- Biochemistry and Molecular Biology; Medicine Administration
- Record Identifier
- 9984627342702771
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