Bacillus anthracis protective antigen: Proteins and Enzymes

Anthrax toxins are composed of three distinct proteins, a protective antigen (PA), a lethal factor (LF) and an edema factor (EF). None of these proteins are toxic by themselves and several studies indicate that the anthrax toxin has the familiar A-B enzymatic binding structure, with PA acting as the binding domain and EF and/or LF acting as the active fragments.