Factor XIII induces the crosslinking of fibrin at terminal stage of blood coagulation. New ELISA methods of a-subunit, b-subunit and a2b2 complex of factor XIII were developed by the author and the following results concerning the activation process of factor XIII were obtained. New ELISA methods for a-subunit, b-subunit and a2b2 complex of factor XIII were specific with high sensitivities on each items and indicated the measurement capacity for simultaneous quantitation of many samples, more over we looked upon the dissociation of a2b2 complex with these methods to able to analyze at the subunit levels of factor XIII in details. When a-subunit dimer of platelets was discharged into the plasma by the use of freezing and thawing method on PRP, it was more easily affected to lose their antigeniety than that of a2b2 complex, a-subunit levels in the plasma of congenital factor XIII deficiencies were measured in very low concentration or below the measurement sensitivity of this ELISA, b-subunit levels in the same plasma were indicated around the half of normal levels. These results were as same as another immunological method. It was suggested that the molecular conformation of a-subunit could be changed by the addition of thrombin in high concentration and consequently a-subunit with thrombin was modifyed to show high antigeniety. It was observed that a2b2 complex was dissociated by the addition of thrombin without calcium ion, and the process of this dissociation of a2b2 complex was remarkably accelerated by the addition of calcium ion. Because a-subunit and b-subunit were adsorved on fibrin clot, it might be presumed that the crosslinking of fibrin molecules could be accelerated locally on the surface of fibrin clot.
N‐glycosylation of blood coagulation factor XIII subunit B and its functional consequence