Lipopolysaccharide-binding proteins of Limulus amebocyte lysate.
Limulus amebocyte lysate, obtained from horseshoe crab (Limulus polyphemus) blood cells, contains a coagulation system which is activated by bacterial lipopolysaccharide (LPS). A chromatographic fraction of Limulus lysate, containing the endotoxin-sensitive factor(s) which initiates the coagulation cascade, was studied. We utilized a photoreactive, cleavable, radiolabeled derivative of Salmonella minnesota LPS, LPS-(p-azidosalicylamido)-1,3'-dithiopropionamide (LPS-ASD), to identify LPS-binding proteins. The lysate fraction was incubated with LPS-ASD, and LPS-binding proteins were identified by autoradiography of sodium dodecyl sulfate-polyacrylamide gels. An 82-kDa protein, a major protein component of this fraction from Limulus lysate, was identified as a LPS-binding protein in a majority of lysates. Incubation of whole Limulus lysate with antiserum to this protein resulted in enhanced sensitivity of the lysate to LPS, suggesting that this 82-kDa protein is a negative regulator of coagulation. A minor 50-kDa protein component of lysate also was identified as a LPS-binding protein and is a candidate for the LPS-sensitive coagulation protein in L. polyphemus.
Roth
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Department of Laboratory Medicine, University of California School of Medicine, San Francisco.
Tobias
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D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry*; D004731:Endotoxins / Q000378:metabolism*; D006737:Horseshoe Crabs / Q000737:chemistry*; D007158:Immunologic Techniques; D008033:Limulus Test; D008070:Lipopolysaccharides / Q000378:metabolism*; D008970:Molecular Weight
D002352:Carrier Proteins; D004731:Endotoxins; D008070:Lipopolysaccharides