title: Protein dynamics observed by tunable mid-IR quantum cascade lasers across the time range from 10ns to 1s.
abstract: We have developed a spectrometer based on tunable quantum cascade lasers (QCLs) for recording time-resolved absorption spectra of proteins in the mid-infrared range. We illustrate its performance by recording time-resolved difference spectra of bacteriorhodopsin in the carboxylic range (1800-1700cm-1) and on the CO rebinding reaction of myoglobin (1960-1840cm-1), at a spectral resolution of 1cm-1. The spectrometric setup covers the time range from 4ns to nearly a second with a response time of 10-15ns. Absorption changes as low as 1×10-4are detected in single-shot experiments at t>1μs, and of 5×10-6in kinetics obtained after averaging 100 shots. While previous time-resolved IR experiments have mostly been conducted on hydrated films of proteins, we demonstrate here that the brilliance of tunable quantum cascade lasers is superior to perform ns time-resolved experiments even in aqueous solution (H2O).
authors.affiliation: Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
authors.forename: Bernd-Joachim
authors.initials: BJ
authors.lastname: Schultz
authors.affiliation: Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Mohrmann
authors.affiliation: Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany; Department of Biochemistry and Molecular Biology, Universitat de València, Dr. Moliner 50, 46100 Burjassot, Spain; Interdisciplinary Research Structure for Biotechnology and Biomedicine (ERI BIOTECMED), Universitat de València, Dr. Moliner 50, 46100 Burjassot, Spain.
authors.forename: Victor A
authors.initials: VA
authors.lastname: Lorenz-Fonfria
authors.affiliation: Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany. Electronic address: joachim.heberle@fu-berlin.de.
authors.forename: Joachim
authors.initials: J
authors.lastname: Heberle
mesh_terms: D001436:Bacteriorhodopsins / Q000737:chemistry*; D002248:Carbon Monoxide / Q000737:chemistry; D007700:Kinetics; D007834:Lasers; D009211:Myoglobin / Q000737:chemistry*; D011789:Quantum Theory; D012996:Solutions; D013055:Spectrophotometry, Infrared; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D009211:Myoglobin; D012996:Solutions; D014867:Water; D001436:Bacteriorhodopsins; D002248:Carbon Monoxide
keywords: Bacteriorhodopsin; Channelrhodopsin; Flash photolysis; Myoglobin; Time-resolved IR spectroscopy