Infrared emission from photoexcited bacteriorhodopsin: studies by Fourier transform infrared spectroscopy

摘要

In the present work, Using Fourier transfonn-infrared (Fr -IR)techRique we w~able to register the infrared emission froma wet film of bacteriorhodopsin (bR) under continuous illumination with visible light (from a lOO-W Xenon lamp) at room temperature. Emitted radiation is DOt induced by temperature rise, it bas a discrete spectrum in the infrared range from 400 up ~ 4000 cm-l. There are the bands relating to a retinelidene chromophore as well as to a protein matrix. By comparing these results with the resonance Rarnan and IR-absorption data the majority of stfetching vibrations can be identified; The agreement in the frequency of bands assigned to the chromophore of bR is very good, whereas the difference occurs in the intensity distribution among the characteristic bands. It was found that the IR-emission spectra displayed two C=C stretching frequencies at 1528 and 1516 cm-1 atttibuted to the parent, bR~. and ~Io-intennediate states, respectively, whose intensity strongly depended ona varying of a wavelength of the incident li~t. The data presented here give new spectral infonnation on the molecular processes occurring in the bR molecule during optical excitation.