title: Participation of bacteriorhodopsin active-site lysine backbone in vibrations associated with retinal photochemistry.
abstract: Bacteriorhodopsin (bR) has been biosynthetically prepared with lysine deuterated at its alpha carbon (C alpha--H). The labeled membranes containing bR were investigated by difference Fourier transform infrared (FTIR) spectroscopy. It has been derived from K/bR and M/bR difference spectra (K and M are photocycle intermediates) that several bands previously assigned to the retinal chromophore are coupled to the C alpha--H. The vibrational modes that exhibit this coupling are principally associated with C15--H and N--H vibrations. [C alpha--2H]Lysine-labeled bR was fragmented enzymatically, and bR structures were regenerated with the C alpha--2H label either on lysine-216 and -172 or on the remaining five lysine residues of the protein. FTIR studies of the regenerated bR system, together with methylation of all lysines except the active-site lysine, reveal that the changes observed due to backbone labeling arise from the active-site lysine. The intensity of the C15--H out-of-plane wag is interpreted as a possible indication of a twist around the C15 = N bond.
authors.affiliation: Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Y
authors.initials: Y
authors.lastname: Gat
authors.forename: M
authors.initials: M
authors.lastname: Grossjean
authors.forename: I
authors.initials: I
authors.lastname: Pinevsky
authors.forename: H
authors.initials: H
authors.lastname: Takei
authors.forename: Z
authors.initials: Z
authors.lastname: Rothman
authors.forename: H
authors.initials: H
authors.lastname: Sigrist
authors.forename: A
authors.initials: A
authors.lastname: Lewis
authors.forename: M
authors.initials: M
authors.lastname: Sheves
mesh_terms: D001436:Bacteriorhodopsins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D003903:Deuterium; D008239:Lysine; D010777:Photochemistry; D011487:Protein Conformation; D012172:Retinaldehyde / Q000502:physiology*; D013055:Spectrophotometry, Infrared
chemical_list: D001436:Bacteriorhodopsins; D003903:Deuterium; D008239:Lysine; D012172:Retinaldehyde