P. Kolodner et al., ELECTRIC-FIELD AND PHOTOCHEMICAL EFFECTS IN D85N MUTANT BACTERIORHODOPSIN SUBSTITUTED WITH 4-KETO-RETINAL, Thin solid films, 302(1-2), 1997, pp. 231-234
All-trans 4-keto-retinal has been incorporated into bleached apomembra
nes of D85N mutant bacteriorhodopsin. The resulting pigment exhibits a
pH-dependent equilibrium between forms with a protonated (pink) and a
n unprotonated (yellow) Schiff base, with pK = 6.15. Optical absorptio
n changes produced by flash illumination of suspensions of the protona
ted and unprotonated forms have been recorded. Applying an electric fi
eld across a thin, dry film of the pink form of the pigment produces s
pectral changes characteristic of Schiff-base deprotonation. These exp
eriments demonstrate that electric-field-induced Schiff-base deprotona
tion, first discovered in blue D85N bacteriorhodopsin, can be the basi
s of electrochromic materials of different colors made using retinal-a
nalog substitution as well as genetic mutation. (C) 1997 Elsevier Scie
nce S.A.