- A globulin in normal serum involved in resistance to infection that participates, in conjunction with other factors, in an alternative pathway to the activation of the terminal components of complement; a deficiency of p. results in the lack of stabilization of the alternative C3-convertase enzyme (an X-linked recessive disorder). SEE ALSO: p. system, component of complement, factor P. [pro- + L. perdo, to destroy]
* * *pro·per·din prō-'pərd-ən n a blood serum protein that participates in the activation of complement in a pathway which does not involve the presence of antibodies
* * *n.a group of substances in blood plasma that, in combination with complement and magnesium ions, is capable of destroying certain bacteria and viruses. The properdin complex occurs naturally, rather than as the result of previous exposure to microorganisms, and its activity is not directed against any particular species. Compare antibody.
* * *pro·per·din (proґpər-din) a nonimmunoglobulin gamma globulin component of the alternative pathway of complement activation; it complexes with C3b and stabilizes alternative pathway C3 and C5 convertases (C3bBb and C3bnBb). Called also factor P.
Medical dictionary. 2011.