Lethal Factor

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.

• Product #169 (LF-A), is native LF, recommended for most users and is provided in a liquid form;
• Product #172 (LF-HMA), the original LF made by List Labs, has been found to carry two additional amino acids, histidine and methionine, on the N-terminal. This product is recommended only for use in assays validated with this product; and finally
• Product #176 (LF E687C) is an enzymatic inactive form of LF, carrying a Glu to Cys substitution in the zinc-binding site.

LF Substrates and Antibodies

List Labs has designed substrates available as MAPKKide® which mimic the native targets for LF, proteins in the MAPKK family. These FRET peptides contain the cleavage site for LF and fluorophores which are quenched based on fluorescence resonance energy transfer (FRET). Cleavage of each substrate by LF releases the fluorophore creating an increase in fluorescent intensity. To follow are available LF peptide substrates carrying three different fluorophores:

• Product #532 is MAPKKide® Plus Specific Substrate for Anthrax Lethal Factor. This peptide is remarkable in its resistance to non-specific cleavage by enzymes which may be present in natural samples. MAPKKide® Plus carries the fluorophore 7-amido-4-methylcoumarin (AMC).
• Product #530 is MAPKKide® utilizing the o-Abz/Dnp FRET pair. A calibration peptide, Product #539 is available for convenient use with the quenched substrate.
• Product #531 is MAPKKide® with the FRET pair DABCYL/FITC.

List offers pair of antibodies directed to LF, suitable for use in and ELISA.

• Product #768L affinity purified and biotinylated Anti-Lethal Factor from B. anthracis (chicken lgY) works to detect the LF as described in the C of A.
• Product #769B Anti-Lethal Factor from B. anthracis (chicken lgY) may be used to capture LF. Additionally, we have demonstrated that the antibody #769B may be used to capture LF and use the MAPKKide®substrate.