Amino acid sequence of a new type of antifreeze protein, from the longhorn sculpin Myoxocephalus octodecimspinosis.
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.
Deng
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Department of Chemistry, Boston University, MA 02215, USA.
Andrews
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Laursen
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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
D021301:Antifreeze Proteins; D021302:Antifreeze Proteins, Type IV; D029941:Fish Proteins; D006023:Glycoproteins; D007053:Ice; C103901:LS-12 antifreeze protein, Myoxocephalus octodecemspinosus; D011506:Proteins