Studies on the Protein Moiety of Endotoxin from Gram-Negative Bacteria: Characterization of the Protein Moiety Isolated by Acetic Acid Hydrolysis of Endotoxin from S. marcescens 08
OKLAHOMA UNIV MEDICAL CENTER OKLAHOMA CITY
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Conjugated protein isolated from the endotoxin complex of Serratia marcescens 08 by 1 acetic acid hydrolysis was characterized by analytical ultracentrifugation, electrophoretic and immunological properties and chemical analysis. The chemical composition of conjugated protein and other degraded fragments of endotoxin showed that all characteristic constituents of lipid A were present exclusively in conjugated protein. Successive treatment of conjugated protein with trypsin and pronase resulted in the isolation of corresponding tryptic and pronase cores which were characterized by an increased content of lipid A constituents. Lipid A was separated as an entity from the conjugated protein only after hydrolysis with 0.1 N hydrochloric acid. Conjugated protein and its tryptic and pronase cores were immunogenic and possessed a common antigenic determinant with simple protein and its corresponding cores. Toxicity studies revealed that both conjugated and simple proteins retained to different degrees the toxic properties of whole endotoxin. Sodium dodecyl sulfate had an enhancing rather than diminishing effect on the toxicity of endotoxin and its various fragments.