Metastable CO binding sites in the photoproduct of a novel cooperative dimeric hemoglobin.
AUTOR(ES)
Song, S
RESUMO
The infrared absorption spectrum of the CO-photoproduct from Scapharca inaequivalvis hemoglobin (Hbl) at 10 K yields only a single line in the "B" state region at 2132 cm-1. This is the same frequency as the B1 line observed in photodissociated vertebrate HbCO and MbCO. No evidence was found for the B2 line detected in vertebrate hemoglobins and myoglobin in the 2118-2120 cm-1 region. These data demonstrate that the protein does not have the same conformationally accessible ligand-binding sites as do vertebrate hemoglobins and myoglobins. The absence of the B2 line indicates that only a single weak site is accessible to the photolyzed CO molecule. These results are in accord with geminate rebinding experiments and ligand escape pathway calculations which have shown that the distal properties of Hbl are distinct from those of tetrameric hemoglobins and vertebrate myoglobins.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1225931Documentos Relacionados
- A quantitative model for the cooperative mechanism of human hemoglobin.
- Nuclear magnetic resonance study of heme-heme interaction in hemoglobin M Milwaukee: implications concerning the mechanism of cooperative ligand binding in normal hemoglobin.
- Ordered water molecules as key allosteric mediators in a cooperative dimeric hemoglobin
- Experimental resolution of cooperative free energies for the ten ligation states of human hemoglobin.
- Probing the energetics of proteins through structural perturbation: sites of regulatory energy in human hemoglobin.
