title: Assay for proteolytic activity using a new fluorogenic substrate (peptidyl-3-amino-9-ethyl-carbazole); quantitative determination of lipopolysaccharide at the level of one picogram.
abstract: A new sensitive fluorimetric assay has been developed using peptidyl-3-amino-9-ethyl-carbazole as substrate. The fluorescence intensity of free 3-amino-9-ethyl-carbazole (AEC) at 460 nm is between two and three orders of magnitude higher than the fluorescence intensity of acyl-AEC. The release of AEC from a peptidyl derivative by proteases may be monitored continuously during the hydrolysis step or may be quantified upon addition of a general inhibitor such as benzamidinium chloride. Using N-benzoyl-arginyl-AEC as substrate, as little as 1 ng trypsin may be detected. Using t-butyloxycarbonyl-Val-Leu-Gly-Arg-AEC and the amoebocyte lysate of Limulus polyphemus, as little as 1 pg lipopolysaccharide can be detected. This fluorimetric method allows detection of trace amounts of lipopolysaccharide (endotoxins) in various biological materials, including sera.
mesh_terms: D000818:Animals; D002227:Carbazoles; D005456:Fluorescent Dyes; D005470:Fluorometry; D006737:Horseshoe Crabs; D008070:Lipopolysaccharides / Q000032:analysis*; D008832:Microchemistry / Q000379:methods; D013053:Spectrophotometry
chemical_list: D002227:Carbazoles; D005456:Fluorescent Dyes; D008070:Lipopolysaccharides; C041333:tert-butyloxycarbonyl-valyl-leucyl-glycyl-arginine-3-amino-9-ethylcarbazole; C041329:N-benzoylarginine-3-amino-9-ethylcarbazole