An immunoradiometric quantitative assay of Escherichia coli recA protein

A two-site immunoradiometric assay of Escherichia coli recA protein is described ; its sensitivity allows the detection of 0.1 ng of recA protein ; it yields a linear response for amounts of recA protein in the 0.1-7 ng range. It can be directly applied to extracts of Escherichia coli obtained by sonication. Salmonella typhimurium extracts contain some cross-reacting material which share common antigenic determinants with Escherichia coli recA protein but differ from it.