ISSN:
1432-1327
Keywords:
Key words Myoglobin-CO
;
Bond distortion
;
Bond energy
;
CO poisoning
;
Hydrogen bond
;
Infrared
;
Raman
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract The paradigm that nature protects us from CO poisoning by forcing the bound CO to bend over in heme proteins, thereby reducing its binding affinity, is now in textbooks, but is nevertheless problematic. Results from vibrational spectroscopy give no evidence for bent CO, although X-ray crystallography continues to indicate appreciable distortions in myoglobin. However, the energetic significance of the discrepancy is doubtful, since new Density Functional Theory calculations indicate that much less energy is required to distort the CO than had been thought, perhaps 2 kcal/mol or less. Binding studies on site-directed mutants of myoglobin suggest that steric hindrance by the distal histidine is worth ca. 1 kcal/mol. While the distal histidine does account for the discrimination by Mb against CO and in favor of O2, most of the effect is due to its H-bond with bound O2.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s007750050164
Permalink
