title: Amino acid sequence of a new type of antifreeze protein, from the longhorn sculpin Myoxocephalus octodecimspinosis.
abstract: A new type of fish antifreeze protein, designated here type IV, has been isolated from the longhorn sculpin, Myoxocephalus octodecimspinosis. Sequence analysis of the protein (LS-12) reveals that it contains 108 amino acids, is blocked at the N-terminus by a pyroglutamyl group and has a high (17%) content of glutamine; it is thus completely unrelated to the earlier described types I, II and III fish antifreeze proteins. Circular dichroism spectra and conformational analysis based on the sequence data indicate that LS-12 has a high helix content and probably folds as a four-helix bundle. LS-12 shows sequence similarity to certain plasma apolipoproteins known to have helix bundle structures, suggesting the possibility that LS-12 may have arisen by recruitment and mutation of a plasma apolipoprotein.
authors.affiliation: Department of Chemistry, Boston University, MA 02215, USA.
authors.forename: G
authors.initials: G
authors.lastname: Deng
authors.forename: D W
authors.initials: DW
authors.lastname: Andrews
authors.forename: R A
authors.initials: RA
authors.lastname: Laursen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D021301:Antifreeze Proteins; D021302:Antifreeze Proteins, Type IV; D029941:Fish Proteins; D005399:Fishes; D005615:Freezing; D006023:Glycoproteins / Q000737:chemistry* / Q000494:pharmacology; D007053:Ice; D008969:Molecular Sequence Data; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000494:pharmacology; D016415:Sequence Alignment; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D021301:Antifreeze Proteins; D021302:Antifreeze Proteins, Type IV; D029941:Fish Proteins; D006023:Glycoproteins; D007053:Ice; C103901:LS-12 antifreeze protein, Myoxocephalus octodecemspinosus; D011506:Proteins