title: Studies on the origin of the alpha-haemolysin produced by Escherichia coli.
abstract: Synthesis of alpha-haemolysin by Escherichia coli was proportional to the amount of meat-broth factor present in the medium and not to bacterial growth. The meat-broth component required for the synthesis of haemolysin was found to have several physical and chemical properties in common with alpha-haemolysin itself. Both molecules are trypsin-sensitive, acidic substances with similar elution volumes when subjected to gel-filtration chromatography with Sepharose 6B. Isotopic labelling experiments in which the bacteria were grown on 14C-labelled meat broth showed that partially purified haemolysin preparations contained molecules of mammalian origin. Similar experiments in which 14C-glucose was used to label bacterial molecules showed that little or no material of bacterial origin was present in the haemolysin preparation. These data suggest that alpha-haemolysin may be produced by bacterial modification of a molecule present in meat broth rather than by synthesis de novo within the bacterial cell.
mesh_terms: D003470:Culture Media; D004355:Drug Stability; D004926:Escherichia coli / Q000032:analysis / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006460:Hemolysin Proteins / Q000032:analysis / Q000096:biosynthesis*; D006358:Hot Temperature; D008460:Meat; D008970:Molecular Weight; D011498:Protein Precursors / Q000032:analysis / Q000378:metabolism
chemical_list: D003470:Culture Media; D006460:Hemolysin Proteins; D011498:Protein Precursors; D005947:Glucose