Primary structure of anti-lipopolysaccharide factor from American horseshoe crab, Limulus polyphemus.

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Abstract

The complete amino acid sequence of anti-lipopolysaccharide (LPS) factor purified from the hemocytes lysate of the American horseshoe crab, Limulus polyphemus, was determined by characterization of the NH2-terminal sequence and the peptides generated after digestion of the protein with lysyl endopeptidase, clostripain, and Staphylococcus aureus V 8 protease. Upon sequencing the peptides by the automated Edman method, the following primary structure was obtained:<br> DGIWTQLIFTLVNKNLATLWQSGDFQFLDHE_??_CHYRIKPTFRRLKWKYKGKFWCPSWTSITGRATKSSRSGAVEHSVRNFVGQAKSSGLITQRQAEQFISQYN<br> During the sequence analysis, two species of the protein, which differed from each other at one locus, were found and characterized. L. polyphemus anti-LPS factor was a basic protein consisting of a single polypeptide chain of 101 residues and a calculated molecular weight of 11, 786 or 11, 800. The hydrophobic NH2-terminal sequence and the clustering of positive charges found in the disulfide loop yielded a typical amphipathic character of this protein. Moreover, L. polyphemus anti-LPS factor showed 83% sequence identity with the Tachypleus tridentatus protein, and the sequence similar to that observed in the EF-hand structure was found to contain in the COOH terminal portions of these proteins, although its function is unknown.

Journal

  • J Biochem (Tokyo)

    J Biochem (Tokyo) 101 (6), 1321-1330, 1987

    The Japanese Biochemical Society

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