We searched for a new cell aggregation factor, and found one we called SAF in the mycelia of a strain of Streptomyces murinus. SAF was purified by active carbon and ion exchange column chromatographies and gel filtration of Sepharose 2B from the homogenized mycelia by sonication. SAF was stable from pH 7 to 9 at 37°C and up to 40°C at pH 8.0. The aggregation activity of SAF was maximum around pH 8.0 at 30°C, and the factor required for its activity metallic ions such as calcium and manganese. The aggregation activity of SAF was inhibited by laminarin, but it was not influenced by various other saccharides. SAF aggregated E. coli, S. aureus, M.luteus, sarcoma 180, and HeLa cells as well as S. marcescens, above all, its highest activity was toward B. subtilis, but P. vulgaris, P. aeruginosa, C. albicans, each type of human erythrocytes, and hepatoma 109A cells were quite resistant to SAF. These properties has proved that SAF is completely different from the other aggregation factors so far reported.

Wesearched for a new cell aggregation factor, and found one we called SAFin the mycelia ofa strain of Streptomyces murinus. SAFwas purified by active carbon and ion exchange column chromatographies and gel filtration of Sepharose 2B from the homogenized mycelia by sonication. SAF was stable from pH 7 to 9 at 37°C and up to 40°C at pH 8.0. The aggregation activity of SAF was maximumaround pH 8.0 at 30°C, and the factor required for its activity metallic ions such as calcium and manganese. The aggregation activity of SAF was inhibited by laminarin, but it was not influenced by various other saccharides. SAFaggregated E. coli, S. aureus, M. luteus, sarcoma 1 80, and HeLa cells as well as S. marcescens, above all, its highest activity was toward B. subtilis, but P. vulgaris, P. aeruginosa, C. albicans, each type of humanerythrocytes, and hepatoma 109Acells were quite resistant to SAF. These properties has proved that SAF is completely different from the other aggregation factors so far reported.

SAF,originally found as an aggregation factor of S. marcescens, was composedof about 75% protein and 25%sugar which consists of glucose, glucosamine, and galactosamine. SAFwas stable against enzymatic digestion (37°C, 1 hr) by some proteinases and polysaccharide-hydrolyzing enzymes. The aggregation activity of the factor toward S. marcescens cells was inhibited by bovine serum albumin, ATP, and EDTA,and SAFactivity was not restored by the addition of a sufficient amount of calcium ions except for the inhibition by EDTA.It was thought that these inhibitors have an effect on SAFitself or on the binding of SAFto the cells. The aggregation of S. marcescens cells by SAF was temperature-and calcium ion-dependent, and consists of two steps, which are the binding of SAFto the cells and subsequent cell aggregation. The first step proceeded at 37°C in the absence of calcium ions, but the second step required calcium ions.

SAF, originally found as an aggregation factor of S. marcescens, was composed of about 75% protein and 25% sugar which consists of glucose, glucosamine, and galactosamine. SAF was stable against enzymatic digestion (37°C, I hr) by some proteinases and polysaccharide-hydrolyzing enzymes. The aggregation activity of the factor toward S. marcescens cells was inhibited by bovine serum albumin, ATP, and EDTA, and SAF activity was not restored by the addition of a sufficient amount of calcium ions except for the inhibition by EDTA. It was thought that these inhibitors have an effect on SAF itself or on the binding of SAF to the cells. The aggregation of S. marcescens cells by SAF was temperature-and calcium ion-dependent, and consists of two steps, which are the binding of SAF to the cells and subsequent cell aggregation. The first step proceeded at 37°C in the absence of calcium ions, but the second step required calcium ions.