title: Azidotetrafluorophenyl retinal analogue: synthesis and bacteriorhodopsin pigment formation.
abstract: The retinal derivative, all-trans-9-(4-azido-2,3,5,6-tetrafluorophenyl)-3,7- dimethyl-2,4,6,8-nonatetraenal, was synthesized by two routes as a potential photoactivatable cross-linking agent for studies in bacteriorhodopsin (BR) of the chromophore interaction with its apoprotein. The retinal analogue formed a stable, moderately functional BR pigment confirming that the ring cavity of the retinal binding site has a significant tolerance for derivatization on that portion of the molecule. Attempts to cross-link the azido chromophore to the protein by photoactivation were unsuccessful. The electron delocalization effect of the conjugated polyene side chain of the retinal appears to interfere with the formation or reactivity of the nitrene intermediate to the extent that photoactivated cross-linking is not achieved. These results demonstrate a limitation to the use of fluorinated aryl azides as photoaffinity reagents.
authors.affiliation: Department of Pharmacology, Medical University of South Carolina, Charleston 29425.
authors.forename: C J
authors.initials: CJ
authors.lastname: Beischel
authors.forename: D R
authors.initials: DR
authors.lastname: Knapp
authors.forename: R
authors.initials: R
authors.lastname: Govindjee
authors.forename: T G
authors.initials: TG
authors.lastname: Ebrey
authors.forename: R K
authors.initials: RK
authors.lastname: Crouch
mesh_terms: D001436:Bacteriorhodopsins / Q000031:analogs & derivatives / Q000138:chemical synthesis*; D002863:Chromogenic Compounds; D010782:Photolysis; D010860:Pigments, Biological / Q000138:chemical synthesis*; D012172:Retinaldehyde / Q000031:analogs & derivatives* / Q000138:chemical synthesis
chemical_list: D002863:Chromogenic Compounds; D010860:Pigments, Biological; C089097:9-(4'-azido-2',3',5',6'-tetrafluorophenyl)-3,7-dimethyl-2,4,6,8-nonatetraenal; D001436:Bacteriorhodopsins; D012172:Retinaldehyde