口腔連鎖球菌由来のα-L-フコシダ-ゼとノイラミニダ-ゼについて

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The fucosyl and sialyl residues are located at the end positions of the carbohydrate chain in various glycoproteins such as salivary glycoproteins, serum glycoproteins and glycoproteins from cellular membranes. Bacterial fucosidase and neuraminidose that split the period linkages from oral glycoproteins may be important in pathological conditions. The purpose of this study was to search for the presence of a-L-fucosidase and/or neuraminidase activity in some oral streptococci. The streptococcal strains were grown in trypticase soy broth at 37°C for 24hr. The resulting cultures were separated into the culture supernatant and whole cells by centrifugation. The enzyme proteins in the culture supernatant were precipitat the addition of 80% saturation of ammonium sulfate and dissolved in phosphate buffer. This mixture was termed the extracellular fraction. Bacterial cells were resuspended in phosphate buffer and disintegrated in a sonicator. This fraction was celled the intracellular fraction for convenience. As substrate for the assay or α-L-fucosidase, porcine submaxillary glycoprotein (PSG) and/or p-nitrophenyl-α-L-fucoside (p-NPF) were used. Neuraminidase activity was determined using human plasma glycoprotein Fr. VI as substrate. Extracellular fucosidase activity was found only in S. sanguis ATCC 10557 and S. mitis ATCC 9811 using PSG, but not p-NPF. The intracellular fractions of several strains possessed fucosidase activity against the PSG and/or p-NPF. Neuraminidase activity was found only in extracellular fractions of S. sanguis ATCC 10557 and S. mitis ATCC 9811. a-L-Fucosidase in the intracellular fraction appeared late in the growth phase, increased to a maximum and then disappered gradually. On the other hand, the activity of extracellular α-L-fucosidase increased quite late in the growth phase and continued to increase quite late in the growth phase and continued to increase during the entire experiment. The qehaviour of the appearance of neuraminidase activity was quite, similar to that of fucosidase. The optimal pH for these enzymes was between 5.5 and 6.5. This study has clearly demonstrated that bacterial fucosidase and neuraminidase were produced by oral streptococci.

口腔連鎖球菌由来のα-L-フコシダ-ゼとノイラミニダ-ゼについて

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