14-Fluorobacteriorhodopsin and other fluorinated and 14-substituted analogues. An extra, unusually red-shifted pigment formed during dark adaptation.
Five vinyl-substituted fluororetinal analogues (8-F, 10-F, 12-F, 14-F, and 13,14-F2) were found to give bacteriorhodopsin analogues with properties similar to those of the parent system. Of these, only 14-fluororetinal was found to give an extra red-shifted BR analogue (lambda max less than or equal to 680 nm) in equilibrium with the normal 587-nm pigment. The 680-nm pigment was enriched upon irradiation. It rearranged to the 587-nm pigment at room temperature (delta E [symbol: see text] = 20.8 kcal/mol). Chromophore extraction experiments revealed the all-trans geometry for the 680-nm pigment. 14-Chlororetinal gave a similarly red-shifted pigment while 14-methylretinal did not. A scheme for dark adaptation of the 14-halogenated bacteriorhodopsins has been proposed in which the new red-shifted pigment was assigned the all-trans, 15-syn geometry.
Tierno
M E
ME
Department of Chemistry, University of Hawaii, Honolulu 96822.
Mead
D
D
Asato
A E
AE
Liu
R S
RS
Sekiya
N
N
Yoshihara
K
K
Chang
C W
CW
Nakanishi
K
K
Govindjee
R
R
Ebrey
T G
TG
D001436:Bacteriorhodopsins / Q000031:analogs & derivatives*; D003623:Dark Adaptation / Q000502:physiology; D006219:Halogens; D008566:Membranes; D008968:Molecular Conformation; D010777:Photochemistry; D010860:Pigments, Biological; D012172:Retinaldehyde / Q000031:analogs & derivatives; D013056:Spectrophotometry, Ultraviolet
C065195:14-fluorobacteriorhodopsin; D006219:Halogens; D010860:Pigments, Biological; D001436:Bacteriorhodopsins; C017827:bacterio-opsin; C065196:14-fluororetinal; D012172:Retinaldehyde