title: Characterization of exoskeletal proteins from the American lobster, Homarus americanus.
abstract: Proteins from the calcified exoskeleton of the lobster, Homarus americanus, were extracted and separated by two-dimensional gel-electrophoresis. Electroblotting the proteins onto polyvinylidene difluoride (PVDF) membranes followed by sequence determination gave 16 N-terminal amino-acid sequences and revealed that further eight proteins were N-terminally blocked. The relative molecular mass, M(r), was obtained for most of the electrophoretically separated proteins by means of matrix-assisted laser desorption mass spectrometry (MALDIMS) after electroelution from Coomassie-stained two-dimensional polyacrylamide gels. Eleven proteins were purified from extracts of the exoskeleton by low pressure ion exchange chromatography and reversed-phase high performance chromatography, and their sequences were determined by combined use of Edman degradation and mass spectrometry. Good agreement was obtained between the M(r)-values measured by mass spectrometry and those calculated from the sequences. Five of the sequenced proteins contain two copies of a previously observed 18-residue sequence motif, while a couple of the remaining sequences show similarity to sequences of exoskeletal proteins from shrimps and spiders. Only limited similarity to insect cuticular proteins was observed.
authors.affiliation: Department of Molecular Biology, Odense University, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Nousiainen
authors.forename: K
authors.initials: K
authors.lastname: Rafn
authors.forename: L
authors.initials: L
authors.lastname: Skou
authors.forename: P
authors.initials: P
authors.lastname: Roepstorff
authors.forename: S O
authors.initials: SO
authors.lastname: Andersen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D008121:Nephropidae / Q000737:chemistry* / Q000235:genetics; D011506:Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D019476:Insect Proteins; D011506:Proteins