Lethal Factor (LF) is the enzymatic subunit of anthrax lethal toxin. When intoxicating a cell, LF binds to PA on the cell surface and translocates through a pore made by seven PA monomers. List Labs offers several forms of LF, all made recombinantly in the native Bacillus anthracis host. The original form, Product #172 (LF-HMA), has been found to carry two additional amino acids, histidine and methionine, on the N-terminal. A newer native form, Product # 169 (LF-A), has an alanine on the N-terminal like the native toxin. The two forms of lethal factor, LF-A and LF-HMA. Additionally, both of these types of LF are produced as Quality Documented (QD) reagents, distinguished by greater control of components, equipment and environment during production and added quality control testing for cellular activity of the final products, Products #9169 and #9172.
Finally, List Labs produces a mutant form of LF, LF E687C, with a Glu to Cys substitution in the zinc-binding site, eliminating the enzymatic activity.