title: Purification and characterization of a beta-1,3-glucan binding protein from plasma of the crayfish Pacifastacus leniusculus.
abstract: The plasma of the crayfish Pacifastacus leniusculus contains a protein which is able to bind to laminarin (a soluble beta-1,3-glucan) and which has been isolated by two independent methods, affinity precipitation with a beta-1,3-glucan or immunoaffinity chromatography. The purified beta-1,3-glucan binding protein was homogenous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It is a monomeric glycoprotein with a molecular mass of approximately 100,000 Da and an isoelectric point of approximately 5.0. Amino acid analysis showed a very high similarity with the amino acid composition of beta-1,3-glucan binding proteins recently purified from two insects, the cockroach Blaberus craniifer and the silkworm Bombyx mori. The N-terminal amino acid sequence was determined to be: H2N-Asp-Ala-Gly-X-Ala-Ser-Leu-Val-Thr-Asn-Phe-Asn-Ser-Ala-Lys-Leu-X-X-Ly s--- Using monospecific rabbit polyclonal antibodies, the presence of this protein has also been shown within the blood cells. The purified beta-1,3-glucan binding protein did not show any peptidase or phenoloxidase activity but was able to enhance the activation of hemocyte-derived peptidase and prophenoloxidase only in the presence of the beta-1,3-glucan, laminarin, whereas mannan, dextran (alpha-glucan), or cellulose (beta-1,4-glucan) incubated with the beta-1,3-glucan binding protein had no effect on these enzyme activities. The beta-1,3-glucan binding protein could only be affinity-precipitated from crayfish plasma by the beta-1,3-glucans laminarin or curdlan (an insoluble beta-1,3-glucan), while mannan or dextran did not bind to the beta-1,3-glucan binding protein. No hemagglutinating activity of the purified beta-1,3-glucan binding protein could be detected.
authors.affiliation: Department of Physiological Botany, University of Uppsala, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Duvic
authors.forename: K
authors.initials: K
authors.lastname: Söderhäll
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D003400:Astacoidea / Q000378:metabolism*; D002352:Carrier Proteins / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D011232:Chemical Precipitation; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D005936:Glucans / Q000378:metabolism*; D007118:Immunoassay; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D008970:Molecular Weight; D014442:Monophenol Monooxygenase / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism / Q000494:pharmacology; D047071:beta-Glucans
chemical_list: D000596:Amino Acids; D002352:Carrier Proteins; D005936:Glucans; D011134:Polysaccharides; D047071:beta-Glucans; C008247:laminaran; C033363:beta-1,3-glucan; D014442:Monophenol Monooxygenase; D010447:Peptide Hydrolases