10066
Biochemistry 2000, 39, 10066-10071
Refinement of the Geometry of the Retinal Binding Pocket in Dark-Adapted Bacteriorhodopsin by Heteronuclear Solid-State NMR Distance Measurements† Michael Helmle,‡,§ Heiko Patzelt,‡,| Andreas Ockenfels,⊥ Wolfgang Ga¨rtner,‡,⊥ Dieter Oesterhelt,‡ and Burkhard Bechinger*,‡ Max-Planck-Institut fu¨ r Biochemie, Am Klopferspitz 18A, 82152 Martinsried, Germany, and Max-Planck-Institut fu¨ r Strahlenchemie, Stiftstrasse 34-36, 45470 Mu¨ lheim an der Ruhr, Germany ReceiVed March 23, 2000; ReVised Manuscript ReceiVed May 24, 2000
ABSTRACT: The bacterial proton pump bacteriorhodopsin (BR) is a 26.5 kDa seven-transmembrane helical protein. Several structural models have been published at g1.55 Å resolution. The initial cis-trans isomerization of the retinal moiety involves structural changes within
