C0003-01A

Goat Anti-C1 Esterase Inhibitor (C1-INH)

C1-INH is a member of the serpin family of proteases, as are alpha-antitrypsin, antithrombin III, and angiotensinogen. These proteins stoichiometrically inactivate their target proteases by forming stable, one-to-one complexes with the protein to be inhibited. Although synthesized primarily by hepatocytes, C1-INH is also synthesized by monocytes. The regulation of the protein production is not completely understood, but, since patients respond clinically to androgen therapy serum levels of C1-INH increase, it is believed that androgens may stimulate C1-INH synthesis. All C1-INH deficient patients are heterozygous; half the normal level of C1-INH is not believed sufficient to prevent attacks. Although named for its action on the first component of complement (C1 esterase), C1-INH also inhibits components of the fibrinolytic, clotting, and kinin pathways. Specifically, C1-INH inactivates plasmin-activated Hageman factor (factor XII), activated factor XI, PTA, and kallikrein. Within the complement system, C1-INH blocks the activation of C1 and the rest of the classic complement pathway by binding to C1r and C1s. Without C1-INH, unchecked activation of C1, C2, and C4 occur before other inhibitors (C4-binding protein and factor I) can halt the cascade.