Cell surface proteins of encapsulated Streptococcus cremoris: identification and immunochemical characterization |
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Authors: | Sirpa Kontusaari Raili Forsen † † |
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Institution: | *Department of Biochemistry, University of Oulu, Linnanmaa, SF-90570 Oulu;?National Public Health Institute, Oulu, PO Box 310, SF-90101 Oulu, Finland |
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Abstract: | Cell surface proteins of two slime-forming, encapsulated Streptococcus cremoris strains, MLS96 and T5 from the fermented milk product viili, were extracted with the non-ionic detergent Triton X-100. The isolated protein antigens were characterized by sodium dodecyl sulphate polyacrylamide gel electrophoresis and immuno-blotting with antisera produced against whole Strep. cremoris cells. When protein profiles of these strains were compared, seven prominent polypeptides were found common to both and were recognized by both antisera. Five of these polypeptides with molecular weights of 70000, 54000, 50000, 47000 and 40000 were identified as cell wall components. The remaining two polypeptides with molecular weights of 42000 and 26000 are being studied further in connection with slime formation for which modified Triton X-100 extraction provides a suitable method for isolation of the surface-associated antigens of lactic streptococci. |
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