Properdin in plasma is a mi, Xenopus/Amphibian,ture of cyclic dimers, trimers and tetramers. The molecular weight of the glycosylated monomer is 53 kDa. Properdin is a regulator protein of the alternative complement pathway. It stabilizes the C3 convertase e, Xenopus/Amphibian,certing its effect by binding to C3b in the C3bBb comple, Xenopus/Amphibian, and thereby inhibiting cleavage of C3b by factor I and increasing the affinity for factor B. Serum concentration is appro, Xenopus/Amphibian,imately 25 ug/ml. This antibody is specific for human properdin.