title: Interaction between lipopolysaccharide and intracellular serine protease zymogen, factor C, from horseshoe crab (Tachypleus tridentatus) hemocytes.
abstract: The interaction between lipopolysaccharide (LPS) and an LPS-sensitive serine protease zymogen, factor C, purified from horseshoe crab (Tachypleus tridentatus) hemocytes, was investigated to elucidate the LPS-mediated activation of factor C. The rate of activation of the zymogen factor C was highly dependent on the concentration of LPS and on temperature, and the curve of amount of LPS versus activation showed saturation at 37 degrees C. Moreover, a high-molecular-mass complex formed between factor C and LPS was found in a gel-filtration experiment on a Sepharose 4B column. This complex formation was also confirmed by double diffusion analysis on agarose plates. Triton X-100, which destroys LPS micelles, strongly inhibited the LPS-mediated activation of factor C but not activated factor C. These results indicate that the binding of factor C with LPS is required for its activation and that only LPS-associated factor C generates the active factor C. On the other hand, the LPS-mediated activation of factor C was strongly inhibited by the S-alkylated heavy chain derived from factor C. In contrast, the S-alkylated factor C-light chain did not show any inhibitory effect on the activation of factor C, suggesting that the heavy chain located in the NH2-terminal portion of factor C contains an LPS-binding region.
authors.affiliation: Department of Biology, Faculty of Science, Kyushu University, Fukuoka.
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: F
authors.initials: F
authors.lastname: Tokunaga
authors.forename: T
authors.initials: T
authors.lastname: Morita
authors.forename: S
authors.initials: S
authors.lastname: Iwanaga
mesh_terms: D000818:Animals; D001773:Blood Cells / Q000201:enzymology*; D002847:Chromatography, Agarose; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003902:Detergents; D004792:Enzyme Precursors / Q000378:metabolism*; D006434:Hemocytes / Q000201:enzymology*; D006737:Horseshoe Crabs / Q000201:enzymology*; D008070:Lipopolysaccharides / Q000378:metabolism*; D017830:Octoxynol; D010084:Oxidation-Reduction; D011092:Polyethylene Glycols; D012697:Serine Endopeptidases / Q000378:metabolism*; D013696:Temperature
chemical_list: D003902:Detergents; D004792:Enzyme Precursors; D008070:Lipopolysaccharides; D011092:Polyethylene Glycols; D017830:Octoxynol; D012697:Serine Endopeptidases