Fibrin Mechanisms and Functions in Nervous System Pathology

Fibrinogen depletion by the snake venom protein ancrod. A. Ancrod is a 258-amino acid serine protease derived from the Malayan pit viper, Calloselasma (Agkistrodon) rhodostoma (photo provided by Mardi Snipes) (B), with thrombin-like specificity for fibrinogen (142, 143). C. Ancrod cleaves only the fibrinopeptide A without removing fibrinopeptide B, thus resulting in improper fibrin polymer formation. Ancrod-cleaved fibrinogen cannot be crosslinked by Factor XIII (transglutaminase) to form fibrin and, thus, is subsequently degraded and depleted from the circulating blood supply.