AN ANTIGEN COMMON TO A WIDE RANGE OF BACTERIA

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Abstract
Common Antigen (CA) of P. aeruginosa was shown to be a protein composed of polypeptide subunits of a MW of .apprx. 62,000. The MW of this protein was estimated to 665,000 by gel filtration on Sepharose CL-6B, to 800,000 by electrophoresis on polyacrylamide gradient gels and to .apprx. 900,000 by ultracentrifugation on a sucrose gradient. By analytical ultracentrifugation with Schlieren optics, a sedimentation coefficient (S20.degree., H2O) of 22.65 was calculated. The isoelectric point was determined to pH 4.4. The antigen was decomposed on exposure to proteolytic enzymes. Polysaccharide, lipid, DNA or RNA were not demonstrated in CA. The amino acid content of CA was determined and no hexosamine or abnormal residues were observed. The antigen was degraded when heated to 100.degree. C for 4 min or when exposed to pH below 4 or above 11 at 4.degree. C. CA was isolated from the cytoplasmic water-soluble fraction of disintegrated bacteria and only trace-amounts could be obtained from envelope fractions after solubilization with Triton X-100.