title: Cross-linking of alpha 2-plasmin inhibitor and fibronectin to fibrin by fibrin-stabilizing factor.
abstract: Two plasma proteins, alpha 2-plasmin inhibitor and plasma fibronectin, are cross-linked to fibrin by plasma transglutaminase (R-glutaminyl-peptide : amine gamma-glutamyl-yltransferase, EC 2.3.2.13, fibrin stabilizing factor) when blood coagulation takes place. The cross-linking reactions of these proteins were analyzed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate (SDS) using these radioactively labeled proteins. Both proteins were cross-linked exclusively to the alpha-chain of fibrin, and each of these cross-linking reactions proceeded independently without being influenced by the other cross-linking reaction. The cross-linking of fibronectin to the alpha-chain proceeded steadily at a rate similar to that of the cross-linked polymerization of the alpha-chain. In contrast, the cross-linking reaction of alpha2-plasmin inhibitor to fibrin proceeded markedly faster than that of fibrin polymerization but did not proceed further after reaching a certain relatively low level of cross-linking. Most of the cross-linked alpha 2-plasmin inhibitor molecules at this stage of the fibrin cross-linking were in the form of complex with the alpha-chain monomer. The complex with the alpha-chain monomer was gradually transformed to a complex with the alpha-chain polymer as the cross-linking polymerization of the alpha chain proceeded. The rate of the transformation was the same as that for the disappearance of the alpha-chain monomer, indicating that whether the alpha-chain was cross-linked to alpha 2-plasmin inhibitor or not, the alpha-chain underwent cross-linking polymerization at the same rate.
mesh_terms: D001777:Blood Coagulation; D004591:Electrophoresis, Polyacrylamide Gel; D005176:Factor XIII / Q000378:metabolism*; D005337:Fibrin / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D046911:Macromolecular Substances; D000979:alpha-2-Antiplasmin / Q000378:metabolism*
chemical_list: D005353:Fibronectins; D046911:Macromolecular Substances; D000979:alpha-2-Antiplasmin; D005337:Fibrin; D005176:Factor XIII