Application

Complement C5 is part of the terminal sequence in the complement pathway. In particular, it is cleaved into C5a and C5b which are responsible for chemotaxis, inflammation, and initiating the formation of the membrane attack complex (MAC). Drugs that inhibit complement C5 have been used in Paroxysmal nocturnal hemoglobinuria (PNH) patients to lessen thrombotic complications by lessening intravascular hemolysis.

Biochem/physiol Actions

Complement component C5 is processed by convertase enzymes in a cascade modulated in a unique way. The multi-subunit catalytic complex initially shows little activity against C5, but instead cleaves C3. A C3 cleavage product C3b covalently attaches to the complex and shifts its specificity to C5 by a factor of 1000.

Other Notes

View more information on the complement pathway at www.sigma-aldrich.com/enzymeexplorer

Quality

Functionally active by a sensitive hemolytic assay.