The hemolytic effect of Salmonella typhi Ty 2 porins

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Abstract
Two outer membrane proteins of S. typhi Ty 2 were extensively co-purified. According to their migration in dodecylsulfate/polyacrylamide gel electrophoresis and solubility characteristics, these proteins are homologous to the 35-kDa (kilodalton) and 36-kDa porins found in S. typhimurium. A porin homologous to the 34-kDa one was not found in S. typhi Ty 2. A critical step in the purification of porins is heating at 100.degree. C in 2% sodium dodecyl sulfate before Sephadex gel filtration. The absence of detergent in aqueous suspensions enhances porin aggregation, these aggregations inducing human red cell lysis. Porins obtained by an alternative procedure consisting of heating at 60.degree. C instead of 100.degree. C were also hemolytic. Using nanomolar concentration of porins a strong influence of temperature on the hemolytic effect was observed. Porin-induced hemolysis was inhibited with anti-porin serum and by treatment with phenylglyoxal, which reacts with the arginine residues of proteins. The membrane-disrupting ability of porin aggregates might explain some pathogenic characteristics of gram-negative bacterial infections.