title: Structural characterisation of human proteinosis surfactant protein A.
abstract: Human surfactant protein-A (SP-A) has been purified from a proteinosis patient and characterised by a combination of automated Edman degradation and mass spectrometry. The complete protein sequence was characterised. The major part of SP-A was shown to consist of SP-A2 gene product, and only a small amount of SP-A1 gene product was shown to be present. A cysteine extension to the N-terminal was indicated by sequence data, but was not definitely proven. All proline residues in the Y position of Gly-X-Y in the collagen-like region were at least partially modified to hydroxy-proline, but no lysine residues were found to be modified. A complex N-linked glycosylation was found on Asn-187 showing great heterogeneity as variants from a mono-antennary to penta-antennary glycosylation with varying amounts of attached pentose were identified. The disulfide bridges in the carbohydrate recognition domain were identified to be in the 1-4, 2-3 pattern common for collectins. Interchain disulfide bridges were discovered between two Cys-48 residues and cysteine residues in the N-terminal region. However, the exact disulfide bridge connections within the bouquet-like ultrastructure could not be established.
authors.affiliation: Department of Molecular Biology, Univesity of Southern Denmark, Odense University, DK-5230 Odense M. Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Berg
authors.forename: R
authors.initials: R
authors.lastname: Leth-Larsen
authors.forename: U
authors.initials: U
authors.lastname: Holmskov
authors.forename: P
authors.initials: P
authors.lastname: Højrup
mesh_terms: D000595:Amino Acid Sequence; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004220:Disulfides / Q000737:chemistry; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011134:Polysaccharides / Q000737:chemistry; D011510:Proteolipids / Q000737:chemistry* / Q000302:isolation & purification; D011649:Pulmonary Alveolar Proteinosis / Q000378:metabolism*; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000737:chemistry* / Q000302:isolation & purification; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014357:Trypsin
chemical_list: D004220:Disulfides; D011134:Polysaccharides; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; C445842:SFTPA1 protein, human; C445843:SFTPA2 protein, human; D014357:Trypsin