Plasma enzyme precursor which, when activated by thrombin in the presence of Ca2+, converts soluble fibrin, q.v. gel to a tough insoluble clot: Laki, Lorand, Science 108, 280 (1948); Lorand, Nature 166, 694 (1950). During the terminal stage of blood-clotting, factor XIII catalyzes the formation of cross-links in the fibrin gel by eliminating NH3 in the transamidation reaction in which the ε-amino group of lysine from a fibrin molecule forms a peptide linkage with a glutaminyl residue from a nearby fibrin monomer: Lorand et al., Biochem. Biophys. Res. Commun. 25, 629 (1966); Fuller, Doolittle, ibid. 694. Trypsin, papain, and reptilase also activate factor XIII: Lorand et al., ibid. 31, 222 (1968). Structure contains two each of two types of soluble proteinaceous subunits called the α and β chains; mol wt of subunits each about 80,000: Schwartz et al., J. Biol. Chem. 248, 1395 (1973). Amino acid sequence studies: Holbrook et al., Biochem. J. 135, 901 (1973). Clinical studies: Cucuianu et al., Thromb. Diath. Haemorrh. 30, 480 (1973). Review: L. Lorand, Ann. N.Y. Acad. Sci. 202, 6-30 (1972); A. G. Loewy, ibid. 41-58; C. G. Curtis, L. Lorand, Haemostasis: Biochemistry, Physiology & Pathology, D. Ogston, B. Bennett, Eds. (Wiley-Interscience, New York, 1977) pp 186-201; eidem, Methods Enzymol. 45B, 177-191 (1976).
Antihemorrhagic.
Hemostatic