Analysis of conformational changes in bacteriorhodopsin upon retinal removal

Josep Cladera, Jaume Torres, Esteve Padrós

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23 Citations (Scopus)


The conformation of bacterioopsin in the apomembrane has been studied by Fourier transform infrared spectroscopy. Resolution enhancement techniques and curve-fitting procedures have been used to determine the secondary structural components from the amide I region. Bacterioopsin contains about 54% helicoidal structure (α(I) and α(II) helices + 310 turns), 21% sheets, 16% reverse turns, and 9% unordered structure. Thus, after retinal removal, all of the secondary structural types of bacteriorhodopsin remain present, and only slight quantitative differences appear. On the other hand, H/D exchange studies show that there is a higher degree of exchange for reverse turns and protonated carboxylic lateral chains in bacterioopsin as compared to bacteriorhodopsin. This gives further support to the idea of a more open tertiary structure of bacterioopsin, and to the consideration of the retinal molecule as an important element in complementing the interhelical interactions in bacteriorhodopsin folding.
Original languageEnglish
Pages (from-to)2882-2887
JournalBiophysical Journal
Issue number6
Publication statusPublished - 1 Jan 1996


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