Watching a protein as it functions with 150-ps time-resolved x-ray crystallography.
We report picosecond time-resolved x-ray diffraction from the myoglobin (Mb) mutant in which Leu29 is replaced by Phe (L29Fmutant). The frame-by-frame structural evolution, resolved to 1.8 angstroms, allows one to literally "watch" the protein as it executes its function. Time-resolved mid-infrared spectroscopy of flash-photolyzed L29F MbCO revealed a short-lived CO intermediate whose 140-ps lifetime is shorter than that found in wild-type protein by a factor of 1000. The electron density maps of the protein unveil transient conformational changes far more dramatic than the structural differences between the carboxy and deoxy states and depict the correlated side-chain motion responsible for rapidly sweeping CO away from its primary docking site.
Schotte
Friedrich
F
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Lim
Manho
M
Jackson
Timothy A
TA
Smirnov
Aleksandr V
AV
Soman
Jayashree
J
Olson
John S
JS
Phillips
George N
GN
Wulff
Michael
M
Anfinrud
Philip A
PA
D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray / Q000379:methods*; D005583:Fourier Analysis; D006418:Heme / Q000737:chemistry; D008024:Ligands; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009211:Myoglobin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010782:Photolysis; D011487:Protein Conformation; D013055:Spectrophotometry, Infrared; D013997:Time Factors; D014907:Whales
D008024:Ligands; D009211:Myoglobin; C018013:carboxymyoglobin; D006418:Heme; D002248:Carbon Monoxide