STREPTOCOCCAL ERYTHROGENIC TOXIN TYPE-C IS NOT A PHOSPHORYLATED PROTEIN - DESCRIPTION OF 2 DIFFERENT PURIFICATION PROCEDURES AND INVESTIGATION OF ITS PHOSPHORYLATION STATE

Erythrogenic toxin type C (ETC) from different streptococcal group A s trains was successively purified by absorption on phenylsepharose, aci dic dialysis of the eluate at 40% saturated ammonium sulphate solution , CM-Sepharose chromatography, finally by immunoaffinity chromatograph y on monoclonal antibodies. Second, after growing of bacteria in the p resence of [P-32]orthophoaphate to phosphorylate ETC, the ETC was puri fied with phenylsepharose following immunoaffinty chromatography. The occurrence of phosphoamino acids in the purified ETC was investigated by an immunoassay. No phosphoamino acids could be detected in the ETC molecule. Also after radiolabelling with P-32 it was not possible to d emonstrate a radioactive signal. The treatment with alkaline phosphata se has no influence on the mitogenicity or position of ETC in isoelect ric focusing. The results obtained led to the conclusion that in contr ast to the literature, ETC is not a phosphorylated protein.