Abstract
SAP, 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. SAP was 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 SAP 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 SAP itself or on the binding of SAP to the cells. The aggregation of S. marcescens cells by SAP was temperature- and calcium ion-dependent, and consists of two steps, which are the binding of SAP 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.
