| Abstract
| - Structural changes in the complex formation betweentransducin and metarhodopsin II, theactivated form of photolyzed rhodopsin, in visual transductionprocesses were analyzed by Fourier transforminfrared spectroscopy. The spectrum of the complex was obtained bysubtracting the contribution ofmetarhodopsin I and uncomplexed metarhodopsin II. The averagedspectrum upon the complex formationwas then compared with that in the conversion ofrhodopsin-to-metarhodopsin II. Frequency shifts ofthepeptide carbonyl vibrations at 1686, 1674, and 1661 cm-1to 1640 cm-1 were observed uponcomplexformation from metarhodopsin II plus transducin. These changesmust have resulted from the strengtheningof H-bonding of one or a few peptide groups but is not ascribable toglobal conformation change. Changesin the frequencies of the peptide amides were also detected. Withregard to intramembrane carboxylicacid residues, no further changes were noticed in the carboxylvibrations of Asp83, Glu122, and Glu113.Only a small change possibly due to Glu134 wasdetected.
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