Proton-NMR studies of native bacteriorhodopsin revealed the existence of about nine relatively mobile aromatic residues out of the 32 totally present in the protein. These nine comprise approximately three tyrosines, two tryptophans and four phenylalanines. Photo-CIDNP data strongly suggest that, aside from phenylalanines, only one tyrosine and one tryptophan residue are exposed to the solvent. These data are discussed in terms of the current structural model for bacteriorhodopsin.
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AcknowledgementTsh: is work was supported by a grant from the North Atlantic Treaty Organization (NATO) Scientific Affairs Division (RG.85/0424). A.S. received a Summer Research Fellowship from Yale University. We thank J. Piittmann-Wunderlich and A. Scholz for excellent technical help.
- Membrane protein
- Proton nuclear resonance
- Side-chain mobility