Istituto di Scienza e Tecnologie dell'Informazione     
Barsanti L., Coltelli P., Evangelista V., Passarelli V., Frassanito A. M., Vesentini N., Santoro F., Gualtieri P. In vivo absorption spectra of the two stable states of the Euglena photoreceptor photocycle. In: Photochemistry and Photobiology, vol. 85 (1) pp. 304 - 312. Wiley-Blackwell, 2009.
Euglena gracilis possesses a simple but sophisticated light detecting system, consisting of an eyespot formed by carotenoids globules and a photoreceptor. The photoreceptor of Euglena is characterized by optical bistability, with two stable states. In order to provide important and discriminating information on the series of structural changes that Euglena photoreceptive protein(s) undergoes inside the photoreceptor in response to light, we measured the in vivo absorption spectra of the two stable states A and B of photoreceptor photocycle. Data were collected using two different devices, i.e. a microspectrophotometer and a digital microscope. Our results show that the photocycle and the absorption spectra of the photoreceptor possess strong spectroscopic similarities with a rhodopsin-like protein. Moreover, the analysis of the absorption spectra of the two stable states of the photoreceptor and the absorption spectrum of the eyespot suggests an intriguing hypothesis for the orientation of microalgae toward light.
URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1751-1097.2008.00438.x/abstract
DOI: 10.1111/j.1751-1097.2008.00438.x
Subject Euglena gracilis
Rhodopsin-like protein
J.3 Life and Medical Sciences
92C05 Biophysics

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