A steric mechanism for inhibition of CO binding to heme proteins.
The crystal structures of myoglobin in the deoxy- and carbon monoxide-ligated states at a resolution of 1.15 angstroms show that carbon monoxide binding at ambient temperatures requires concerted motions of the heme, the iron, and helices E and F for relief of steric inhibition. These steps constitute the main mechanism by which heme proteins lower the affinity of the heme group for the toxic ligand carbon monoxide.
Kachalova
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Max-Planck-Arbeitsgruppen für Strukturelle Molekularbiologie, Arbeitsgruppe Proteindynamik, Notkestrabetae 85, 22603 Hamburg, Germany.
Popov
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Bartunik
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D000818:Animals; D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D006639:Histidine / Q000737:chemistry / Q000378:metabolism; D006860:Hydrogen Bonding; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D008786:Metmyoglobin / Q000737:chemistry; D008958:Models, Molecular; D009211:Myoglobin / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D013696:Temperature; D014633:Valine / Q000737:chemistry / Q000378:metabolism
D008024:Ligands; D009211:Myoglobin; C018013:carboxymyoglobin; C055547:deoxymyoglobin; D008786:Metmyoglobin; D006418:Heme; D006639:Histidine; D002248:Carbon Monoxide; D007501:Iron; D014633:Valine; D009584:Nitrogen