Controlling the pKa of the bacteriorhodopsin Schiff base by use of artificial retinal analogues

Journal Article · Thu May 01 00:00:00 EDT 1986 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.83.10.3262· OSTI ID:5430135

Sheves, M; Albeck, A; Friedman, N; Ottolenghi, M

Artificial bacteriorhodopsin pigments based on synthetic retinal analogues carrying an electron-withdrawing CF3 substituent group were prepared. The effects of CF3 on the spectra, photocycles, and Schiff base pKa values of the pigments were analyzed. A reduction of 5 units in the pKa of the Schiff base is observed when the CF3 substituent is located at the C-13 polyene position, in the vicinity of the protonated Schiff base nitrogen. The results lead to the unambiguous characterization of the (direct) titration of the Schiff base in bacteriorhodopsin and to the conclusion that the deprotonation rate of the Schiff base during the photocycle (i.e., the generation of the M412 intermediate) is determined by a structural change in the protein.

• Research Organization: Weizmann Institute of Science, Rehovot (Israel)
• OSTI ID: 5430135
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 10
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
RHODOPSIN
BIOCHEMICAL REACTION KINETICS
ALDEHYDES
CAROTENOIDS
NITROGEN
PHOTOSYNTHESIS
SCHIFF BASES
STRUCTURE-ACTIVITY RELATIONSHIPS
CHEMICAL REACTIONS
ELEMENTS
HYDROCARBONS
IMINES
KINETICS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PIGMENTS
PROTEINS
REACTION KINETICS
SYNTHESIS
TERPENES
550200* - Biochemistry