[Expression and characterization of the recombination anthrax lethal factor].

The gene encoding anthrax lehtal factor (LF) was cloned into a secretory expression plasmid and then expressed in periplasmic space of E. coli. The recombinant LF (rLF) expressed was about 4% of the total proteins in E. coli. About 3 mg electrophoresis purity rLF could be obtained after the purification of 1 liter culure using ion exchange chromatography and gel filtration. The result of sequencing assay showed that the N-terminal amino acid sequence of rLF was identical to the N-terminal sequence of natural LF. In vitro toxicity analysis also shows that rLF has an excellent biological activity. The successful expression of rLF has placed a solid foundation for the research on toxicity mechanism of LF, developing new anthrax vaccines, and screening for inhibitors against anthrax toxin.