title: Interaction of tryptophan-182 with the retinal 9-methyl group in the L intermediate of bacteriorhodopsin.
abstract: An intense indole N-H stretching vibrational band at 3486 cm-1 in the difference Fourier transform infrared spectrum is one of the characteristic features of the L intermediate of bacteriorhodopsin [Maeda, Sasaki, Ohkita, Simpson, & Herzfeld (1992) Biochemistry 31, 12543]. This band is now assigned to tryptophan-182. The Trp182-->Phe (W182F) protein shows specific features in the difference spectrum in the visible region upon L formation, and exhibits great delay in the L-M conversion. Fourier transform infrared difference spectra further indicate that while the intensity of the C-methyl in-plane bending vibration at 1009 cm-1 is lost in the L intermediate of the wild type, its intensity remains high in the W182F protein. The intensity of the N-H stretching vibration upon L formation is diminished considerably in an artificial bacteriorhodopsin containing 9-desmethylretinal. It also exhibits delayed M formation. These results suggest that Trp182 interacts with the retinal side chain through the 9-methyl group, and thereby affects the L-to-M conversion.
authors: Department of Biophysics, Faculty of Science, Kyoto University, Japan.
authors: Y
authors: Y
authors: Yamazaki
authors: J
authors: J
authors: Sasaki
authors: M
authors: M
authors: Hatanaka
authors: H
authors: H
authors: Kandori
authors: A
authors: A
authors: Maeda
authors: R
authors: R
authors: Needleman
authors: T
authors: T
authors: Shinada
authors: K
authors: K
authors: Yoshihara
authors: L S
authors: LS
authors: Brown
authors: J K
authors: JK
authors: Lanyi
mesh_terms: D001436:Bacteriorhodopsins / Q000235:genetics / Q000378:metabolism*; D006217:Halobacterium; D008745:Methylation; D009154:Mutation; D011522:Protons; D012172:Retinaldehyde / Q000378:metabolism*; D012545:Schiff Bases; D017550:Spectroscopy, Fourier Transform Infrared; D014364:Tryptophan / Q000378:metabolism*
chemical_list: D011522:Protons; D012545:Schiff Bases; D001436:Bacteriorhodopsins; D014364:Tryptophan; D012172:Retinaldehyde