Effects of Microbiol polysaccharides on cancer metastasis

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We are studying biological functions of sugar and its relation to disease. Polysialic acid is suggested to relate cancer-metastasis in addition to the function as a component of N-CAM.We therefore purified sialydase from a coliphage and cloned the enzyme gene. This sialydase was unique as endosialydase, since minimun substrate size was sialyltrimer and the final product from polysialic acid was sialyldimer. The enzyme was homotetramer and composed of 120 Kd subunit.We also studied the capsular polysaccharide of Streptococcus agalactiae which has sialyl lactosamine polymer. Sialyl lactosamine is an analog of sialyl Lewis sugar which binds L-selection. We therefore studied the function of this sugar by using anti-L-selection antibody. We found that the antibody induced the aggregation of T-lymphocytes by elevating intracellular calcium concentration. We also found that T-cell growth by the stimulation of staphyrococcul superantigen was enhanced by anti-selectin antibody.