title: The three-dimensional structure of porin from Rhodobacter capsulatus at 3 A resolution.
abstract: The crystal structure of porin from Rhodobacter capsulatus strain 37b4 has been solved at 3.0 A (1 A = 0.1 nm) resolution by multiple isomorphous replacement and solvent-flattening. The three pores of the trimer are well defined in the electron density map. Each pore consists of a 16-stranded beta-barrel which traverses the membrane as a tube. Near its center the tube is narrowed by chain segments protruding from the inner wall of the barrel that form an eye-let with an irregular cross-section of about 6 A by 10 A. The eye-let has an axial length of about 10 A; it defines the exclusion limit for diffusing particles.
authors.affiliation: Institut für Organische Chemie und Biochemie, Freiburg, FRG.
authors.forename: M S
authors.initials: MS
authors.lastname: Weiss
authors.forename: T
authors.initials: T
authors.lastname: Wacker
authors.forename: J
authors.initials: J
authors.lastname: Weckesser
authors.forename: W
authors.initials: W
authors.lastname: Welte
authors.forename: G E
authors.initials: GE
authors.lastname: Schulz
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000302:isolation & purification; D008565:Membrane Proteins / Q000302:isolation & purification; D008958:Models, Molecular; D018272:Porins; D011487:Protein Conformation; D012244:Rhodospirillaceae / Q000032:analysis*; D014961:X-Ray Diffraction
chemical_list: D001425:Bacterial Outer Membrane Proteins; D008565:Membrane Proteins; D018272:Porins