Purified colicin as cytotoxic agent of neoplasia: comparative study with crude colicin.

Purification of a bacteriocin, colicin, from Escherichia coli HSC10, is described. A 1,800 fold purified colicin was obtained and found to be an acidic polypeptide with a molecular weight of 82,000 daltons. The effect of colicin on bacterial and mammalian cells during the transition from a crude to a pure preparation is given. A turbidimetric assay for bacterial growth inhibition and 3H-thymidine uptake inhibition for measuring the effect on mammalian cells, was used. Colicin HSC10 caused DNA loss from the bacteriocin-sensitive mammalian cells, which increased with dose and time of exposure. Therefore, flow-cytometry, which detects DNA loss from the bacteriocin-affected mammalian cells, was also used to evaluate the bacteriocin potency. Similar quantitative results were obtained to those using 3H-thymidine uptake inhibition, in terms of microgram protein of pure colicin required to affect adversely 50% of the cells. The bacteriocins were found to retain their activity following freezing and thawing, both as crude and pure preparations, against both bacterial and mammalian cells.

PMID: 3891240 [PubMed - indexed for MEDLINE]