title: Primary structure of porin from Rhodobacter capsulatus.
abstract: The primary structure of the integral membrane protein porin from the purple bacterium Rhodobacter capsulatus was determined. The protein was cleaved with trypsin, CNBr and Asp-N protease. The peptides were isolated, sequenced and aligned to a total length of 301 residues with an Mr of 31,536. The low isoelectric point of 3.9 is confirmed by the high excess of 34 Asp and 17 Glu (16.9%) over 10 Lys, 7 Arg and 2 His (6.3%). Overall sequence similarity to other porins is not evident when using sequence alignment programs. However, a partial relationship to Neisseria porins seems to exist. The established sequence has been used as the basis for a three-dimensional structure determination by X-ray diffraction at 0.18-nm resolution. The arrangement of the sequence in the 16-stranded beta-barrel of porin is given. Some sequence-structure correlations are discussed.
authors.affiliation: Institut für Organische Chemie und Biochemie der Universität Freiburg, Federal Republic of Germany.
authors.forename: E
authors.initials: E
authors.lastname: Schiltz
authors.forename: A
authors.initials: A
authors.lastname: Kreusch
authors.forename: U
authors.initials: U
authors.lastname: Nestel
authors.forename: G E
authors.initials: GE
authors.lastname: Schulz
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D003488:Cyanogen Bromide; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification; D018272:Porins; D011487:Protein Conformation; D016354:Rhodobacter capsulatus / Q000378:metabolism*; D014357:Trypsin
chemical_list: D001425:Bacterial Outer Membrane Proteins; D010446:Peptide Fragments; D018272:Porins; D014357:Trypsin; D003488:Cyanogen Bromide