Purification and properties of a protein surface antigen of Streptococcus mutants
Microbios 25(99): 7-18
ISSN/ISBN: 0026-2633 PMID: 393961 Accession: 006229049
A protein, designated antigen [Ag] III, was extracted from cells and culture supernatant of S. mutans serotype c and purified by (NH4)2SO4 precipitation followed by chromatography on anion-exchange and gel filtration columns. Monospecific antisera were raised by injecting purified Ag III in rabbits. Ag III prepared from cells and supernatants appeared identical by reaction with antisera and were of similar chemical composition and physicochemical properties. Ag III was resistant to most proteolytic enzymes, but pepsin digestion decreased its MW from 44,000 to 24,000 without destroying antigenic activity. Immunofluorescence showed that Ag III was located at or near the cell surface of S. mutans serotypes b, c, e and f. [This may be relevant to studies of immunity against dental caries.].