@article{mbs:/content/journal/micro/10.1099/00221287-15-1-154, author = "Pollock, M. R.", title = "The Cell-bound Penicillinase of Bacillus cereus", journal= "Microbiology", year = "1956", volume = "15", number = "1", pages = "154-169", doi = "https://doi.org/10.1099/00221287-15-1-154", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-15-1-154", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "SUMMARY: Only 30–50 % of the cell-bound penicillinase of Bacillus cereus NRRL 569 is neutralized by antiserum prepared against the exo-penicillinase. The unneutralizable fraction is not decreased by cell disintegration which liberates a proportion of the cell-bound enzyme into solution. Absence of neutralization cannot therefore be explained by the existence of a mechanical barrier which prevents access of antibody; it has in fact been shown to be due to the presence of another type of penicillinase, not liberated from the cells, which is enzymically similar to, but immunologically and physico-chemically distinct from, the exo-enzyme. This cell-bound penicillinase has been separated from the exo-enzyme by fractional precipitation with ammonium sulphate. It is inducible by penicillin, like the exo-enzyme, and is present in cells of the constitutive mutant strain, 569/H.", }