Table 1

Preparations and sources of anthrax lethal toxin components recombinant protective antigen (rPA) and lethal factor (rLF)

ReagentaSourceb (lot no.)Expression vector% of N-terminal amino acid sequencec
rPAEmergent (02-PUR-10-002)pBP103EVKQE... (95)
rLF-HMAEEmergent (03-PUR-10-001)pSJ115HMAGG... (95)
rLF-HMALList Biologicals (1722BB)pSJ115HMAGG... (21)
rLF-AEmergent (08-PUR-12-001)pSJ115b...AGGHG... (95)
rLF-dEmergent (011311)pSJ115...AGGHG.../...GHG... (50/50)
  • a rLF-A, native amino acid sequence; rLF-HMA, additional N-terminal His and Met residues; rLF-d, rLF-HMAE digested with N-terminal dipeptidase.

  • b Emergent BioSolutions, Inc. (Gaithersburg, MD), and List Biological Laboratories, Inc. (Campbell, CA).

  • c Protein N-terminal integrity was assessed via Edman degradation sequencing expressed as the percentage of the expected N-terminal amino acid sequence in each preparation. A total of 4 production lots of rLF-A showed similar results, and at least 7 production lots of rLF-HMAE showed similar results (all lots showed acceptable purity of ≥95% as assessed by N-terminal sequencing).