[A comparative study of 2 substances produced by the Streptococcus sp. Thom-1606 strain].

Among the substances secreted by Streptococcus sp. Thom-1606 [correction of TOM-1606], two substances exhibiting opposite biological action have been detected. Their antigenic structure, as indicated by the data of immunoprecipitation in agar, are not identical. The compounds contained in the substance with antibacterial action have molecular weight below 10 KD, Stokes' radium equal to 1.10 +/- 0.15 nm and electrophoretic mobility approximating that of d1-fraction of human blood serum. The compounds contained in the substance inhibiting the antibacterial activity of the preparation have molecular weight within the range 70-100 KD, Stokes' radius equal to 3.52 +/- 0.25 nm and electrophoretic mobility approximating to that of gamma-globulin of human blood serum. The removal of the inhibiting substance by ultrafiltration and chromatographic techniques enhanced the antibacterial activity of the commercial preparation tomicide.