Polarized Fourier transform infrared spectroscopy of bacteriorhodopsin. Transmembrane alpha helices are resistant to hydrogen/deuterium exchange

Journal Article · Sat Dec 01 04:00:00 EST 1990 · Biophysical Journal; (USA)

DOI:https://doi.org/10.1016/S0006-3495(90)82498-X· OSTI ID:6061583

Earnest, T N; Herzfeld, J; Rothschild, K J ^[1]

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1. Boston Univ., MA (USA)

The secondary structure of bacteriorhodopsin has been investigated by polarized Fourier transform infrared spectroscopy combined with hydrogen/deuterium exchange, isotope labeling and resolution enhancement methods. Oriented films of purple membrane were measured at low temperature after exposure to H2O or D2O. Resolution enhancement techniques and isotopic labeling of the Schiff base were used to assign peaks in the amide I region of the spectrum. alpha-helical structure, which exhibits strong infrared dichroism, undergoes little H/D exchange, even after 48 h of D2O exposure. In contrast, non-alpha-helical structure, which exhibits little dichroism, undergoes rapid H/D exchange. A band at 1,640 cm-1, which has previously been assigned to beta-sheet structure, is found to be due in part to the C = N stretching vibration of protonated Schiff base of the retinylidene chromophore. We conclude that the membrane spanning regions of bR consist predominantly of alpha-helical structure whereas most beta-type structure is located in surface regions directly accessible to water.

• OSTI ID: 6061583
• Journal Information: Biophysical Journal; (USA), Journal Name: Biophysical Journal; (USA) Vol. 58:6; ISSN 0006-3495; ISSN BIOJA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505 -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
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59 BASIC BIOLOGICAL SCIENCES
DEUTERIUM
FOURIER TRANSFORMATION
HYDROGEN ISOTOPES
IMINES
INFRARED SPECTRA
INTEGRAL TRANSFORMATIONS
ISOTOPES
LIGHT NUCLEI
MEMBRANE PROTEINS
MEMBRANES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOSYNTHETIC MEMBRANES
PIGMENTS
PROTEIN STRUCTURE
PROTEINS
RHODOPSIN
SCHIFF BASES
SPECTRA
SPECTROPHOTOMETRY
STABLE ISOTOPES
TRANSFORMATIONS