Perturbations of the distal heme pocket in human myoglobin mutants probed by infrared spectroscopy of bound CO: correlation with ligand binding kinetics.
AUTOR(ES)
Balasubramanian, S
RESUMO
The infrared spectra of CO bound to human myoglobin and myoglobin mutants at positions His-64, Val-68, Asp-60, and Lys-45 on the distal side have been measured between 100 and 300 K. Large differences are observed with mutations at His-64 and Val-68 as well as with temperature and pH. Although distal His-64 is found to affect CO bonding, Val-68 also plays a major role. The variations are analyzed qualitatively in terms of a simple model involving steric interaction between the bound CO and the distal residues. A strong correlation is found between the final barrier height to CO recombination and the CO stretch frequency: as compared to wild type, the barrier is smaller in those mutants that have a higher CO stretch frequency (vCO) and vice versa. Possible reasons for this correlation are discussed. It is emphasized that the temperature and pH dependence of both the kinetics and the infrared spectra must be measured to obtain a consistent picture.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=46584Documentos Relacionados
- Pressure effects on the proximal heme pocket in myoglobin probed by Raman and near-infrared absorption spectroscopy.
- Ligand binding to heme proteins: II. Transitions in the heme pocket of myoglobin.
- Neonatal plasminogen displays altered cell surface binding and activation kinetics. Correlation with increased glycosylation of the protein.
- Cytochrome oxidase (a3) heme and copper observed by low-temperature Fourier transform infrared spectroscopy of the CO complex.
- Stereodynamic properties of the cooperative homodimeric Scapharca inaequivalvis hemoglobin studied through optical absorption spectroscopy and ligand rebinding kinetics.
