Fourier transform infrared studies of active-site-methylated rhodopsin. Implications for chromophore-protein interaction, transducin activation, and the reaction pathway

Journal Article · Fri Mar 01 00:00:00 EST 1991 · Biophysical Journal; (United States)

DOI:https://doi.org/10.1016/S0006-3495(91)82279-2· OSTI ID:5510943

Ganter, U M; Longstaff, C; Pajares, M A; Rando, R R; Siebert, F ^[1]

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1. Institut fuer Biophysik Und Strahlenbiologie, Albert-Ludwigs-Universitaet Freiburg (West Germany)

Fourier transform infrared studies of active-site-methylated rhodopsin (ASMR) show that, as compared to unmodified rhodopsin, the photoreaction is almost unchanged up to the formation of lumirhodopsin. Especially, the deviations are much smaller than those observed for the corresponding intermediates of 13-desmethyl-rhodopsin. In metarhodopsin-I, larger alterations are present with respect to the three internal carboxyl groups. Similar deviations have been observed in meta-I of 13-desmethyl-rhodopsin. This indicates that, in agreement with our previous investigations, these carboxyl groups are located in close proximity to the chromophore. Because this latter pigment is capable, when bleached, of activating transducin, our data provide support for the earlier conclusion that deprotonation of the Schiff base is a prerequisite for transducin activation. The positions of the C = C and C - C stretching modes of the retinal suggest that the redshift observed in ASMR and its photoproducts can be explained by an increased distance of the Schiff base from the counterion(s). It is further shown that the photoreaction does not stop at metarhodopsin-I, but that this intermediate directly decays to a metarhodopsin-III-like species.

• OSTI ID: 5510943
• Journal Information: Biophysical Journal; (United States), Vol. 59:3; ISSN 0006-3495
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
RHODOPSIN
FOURIER ANALYSIS
BIOPHYSICS
FOURIER TRANSFORMATION
INFRARED SPECTRA
METHYLATION
PHOTOCHEMISTRY
SCHIFF BASES
CHEMICAL REACTIONS
CHEMISTRY
IMINES
INTEGRAL TRANSFORMATIONS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PIGMENTS
PROTEINS
SPECTRA
TRANSFORMATIONS
550200* - Biochemistry