Infrared spectroscopic study of photoreceptor membrane and purple membrane. Protein secondary structure and hydrogen deuterium exchange

Journal Article · Sat Mar 15 04:00:00 EST 1986 · J. Biol. Chem.; (United States)

OSTI ID:5682381

Downer, N W; Bruchman, T J; Hazzard, J H

Infrared spectroscopy in the interval from 1800 to 1300 cm-1 has been used to investigate the secondary structure and the hydrogen/deuterium exchange behavior of bacteriorhodopsin and bovine rhodopsin in their respective native membranes. The amide I' and amide II' regions from spectra of membrane suspensions in D2O were decomposed into constituent bands by use of a curve-fitting procedure. The amide I' bands could be fit with a minimum of three theoretical components having peak positions at 1664, 1638, and 1625 cm-1 for bacteriorhodopsin and 1657, 1639, and 1625 cm-1 for rhodopsin. For both of these membrane proteins, the amide I' spectrum suggests that alpha-helix is the predominant form of peptide chain secondary structure, but that a substantial amount of beta-sheet conformation is present as well. The shape of the amide I' band was pH-sensitive for photoreceptor membranes, but not for purple membrane, indicating that membrane-bound rhodopsin undergoes a conformation change at acidic pH. Peptide hydrogen exchange of bacteriorhodopsin and rhodopsin was monitored by observing the change in the ratio of integrated absorbance (Aamide II'/Aamide I') during the interval from 1.5 to 25 h after membranes were introduced into buffered D2O. The fraction of peptide groups in a very slowly exchanging secondary structure was estimated to be 0.71 for bacteriorhodopsin at pD 7. The corresponding fraction in vertebrate rhodopsin was estimated to be less than or equal to 0.60. These findings are discussed in relationship to previous studies of hydrogen exchange behavior and to structural models for both proteins.

• Research Organization: Univ. of Arizona, Tucson
• OSTI ID: 5682381
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 8; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505 -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
CAROTENOIDS
CATTLE
DEUTERIUM
DOMESTIC ANIMALS
ELEMENTS
HYDROCARBONS
HYDROGEN
HYDROGEN ISOTOPES
INFRARED SPECTRA
ISOTOPES
ISOTOPIC EXCHANGE
LIGHT NUCLEI
MAMMALS
MEMBRANES
MOLECULAR STRUCTURE
NONMETALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PHOTOSYNTHETIC MEMBRANES
PIGMENTS
PROTEINS
RHODOPSIN
RUMINANTS
SPECTRA
STABLE ISOTOPES
TERPENES
VERTEBRATES