title: Effects of solvent viscosity on ligand interconversion dynamics in the primary docking site of heme proteins.
abstract: Interconversion dynamics of the ligand in the primary docking site of myoglobin (Mb) and hemoglobin (Hb) in trehalose and glycerol/D2O mixtures at 283 K was investigated by probing time-resolved vibrational spectra of CO photolyzed from these proteins. The interconversion dynamics in viscous media are similar to those in aqueous solution, indicating that it is minimally coupled to the solvent-coupled large-scale protein motion. Interconversion rates in the heme pocket of Hb in water solution are slower than those of Mb in trehalose glass, suggesting that the interconversion barrier in Hb is intrinsically higher than that in Mb and is not modified by the solvent viscosity.
authors.affiliation: Department of Chemistry, Pusan National University, Busan 609-735, Korea.
authors.forename: Seongheun
authors.initials: S
authors.lastname: Kim
authors.forename: Jeonghee
authors.initials: J
authors.lastname: Heo
authors.forename: Manho
authors.initials: M
authors.lastname: Lim
mesh_terms: D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry / Q000378:metabolism; D017666:Deuterium Oxide / Q000737:chemistry; D005990:Glycerol / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism; D009211:Myoglobin / Q000737:chemistry* / Q000378:metabolism; D012997:Solvents; D013055:Spectrophotometry, Infrared; D013816:Thermodynamics; D014199:Trehalose / Q000737:chemistry; D014783:Viscosity
chemical_list: D006454:Hemoglobins; D009211:Myoglobin; D012997:Solvents; D002248:Carbon Monoxide; D014199:Trehalose; D017666:Deuterium Oxide; D005990:Glycerol