title: Tracking ligand-migration pathways of carbonmonoxy myoglobin in crystals at cryogenic temperatures.
abstract: In order to explore the ligand-migration dynamics in myoglobin induced by photodissociation, cryogenic X-ray crystallographic investigations of carbonmonoxy myoglobin crystals illuminated by continuous wave and pulsed lasers at 1-15 kHz repetition rate have been carried out. Here it is shown that this novel method, extended pulsed-laser pumping of carbonmonoxy myoglobin, promotes ligand migration in the protein matrix by crossing the glass transition temperature repeatedly, and enables the visualization of the migration pathway of the photodissociated ligands in native Mb at cryogenic temperatures. It has revealed that the migration of the CO molecule into each cavity induces structural changes of the amino-acid residues around the cavity which result in the expansion of the cavity. The sequential motion of the ligand and the cavity suggests a self-opening mechanism of the ligand-migration channel arising by induced fit.
authors.affiliation: Department of Materials Science, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan.
authors.forename: Ayana
authors.initials: A
authors.lastname: Tomita
authors.forename: Tokushi
authors.initials: T
authors.lastname: Sato
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Nozawa
authors.forename: Shin-ya
authors.initials: SY
authors.lastname: Koshihara
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Adachi
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D009211:Myoglobin / Q000737:chemistry*; D011487:Protein Conformation; D013055:Spectrophotometry, Infrared; D013696:Temperature
chemical_list: D000596:Amino Acids; D008024:Ligands; D009211:Myoglobin; C018013:carboxymyoglobin