1. Carbon monoxide recombination dynamics in truncated hemoglobins studied with visible-pump midIR-probe spectroscopy
- Author
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Barbara Patrizi, Roberto Righini, Agnese Marcelli, Natascia Sciamanna, Alberto Boffi, Mariangela Di Donato, Manuela Lima, Andrea Lapini, Paolo Foggi, European Laboratory for Non-Linear Spectroscopy (LENS), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Istituto Nazionale di Ottica (INO), Consiglio Nazionale delle Ricerche (CNR), Dipartimento di Chimica [Perugia], Università degli Studi di Perugia (UNIPG), Department of Biochemical Sciences 'Rossi Fanelli', Institut Pasteur, Fondation Cenci Bolognetti - Istituto Pasteur Italia, Fondazione Cenci Bolognetti, and Réseau International des Instituts Pasteur (RIIP)-Réseau International des Instituts Pasteur (RIIP)-Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome]
- Subjects
MESH: Photolysis ,Light ,Spectrophotometry, Infrared ,Infrared ,HEME POCKET ,Heme ,010402 general chemistry ,Photochemistry ,01 natural sciences ,INFRARED-SPECTROSCOPY ,BACILLUS-SUBTILIS ,03 medical and health sciences ,chemistry.chemical_compound ,Actinomycetales ,Materials Chemistry ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Physical and Theoretical Chemistry ,Spectroscopy ,030304 developmental biology ,OXYGEN SENSOR FIXL ,0303 health sciences ,Carbon Monoxide ,Photolysis ,MESH: Kinetics ,MESH: Spectrophotometry, Infrared ,Photodissociation ,Truncated Hemoglobins ,PRIMARY DOCKING SITE ,MESH: Bacillus subtilis ,MESH: Light ,0104 chemical sciences ,Surfaces, Coatings and Films ,MESH: Actinomycetales ,Kinetics ,chemistry ,Absorption band ,MESH: Heme ,MESH: Truncated Hemoglobins ,MESH: Carbon Monoxide ,Recombination ,Carbon monoxide ,Visible spectrum ,Bacillus subtilis - Abstract
International audience; Carbon monoxide recombination dynamics upon photodissociation with visible light has been characterized by means of ultrafast visible-pump/MidIR probe spectroscopy for the truncated hemoglobins from Thermobifida fusca and Bacillus subtilis. Photodissociation has been induced by exciting the sample at two different wavelengths: 400 nm, corresponding to the heme absorption in the B-band, and 550 nm, in the Q-bands. The bleached iron-CO coordination band located at 1850-1950 cm(-1) and the free CO absorption band in the region 2050-2200 cm(-1) have been observed by probe pulses tuned in the appropriate infrared region. The kinetic traces measured at 1850-1950 cm(-1) reveal multiexponential subnanosecond dynamics that have been interpreted as arising from fast geminate recombination of the photolyzed CO. A compared analysis of the crystal structure of the two proteins reveals a similar structure of their distal heme pocket, which contains conserved polar and aromatic amino acid residues closely interacting with the iron ligand. Although fast geminate recombination is observed in both proteins, several kinetic differences can be evidenced, which can be interpreted in terms of a different structural flexibility of the corresponding heme distal pockets. The analysis of the free CO band-shape and of its dynamic evolution brings out novel features about the nature of the docking site inside the protein cavity.
- Published
- 2012
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