Kinetic and equilibrium metal-ion-binding behaviour reflected in a metal-ion-dependent antigenic determinant in bovine prothrombin. Comparison with bovine prothrombin fragment 1

• Published in: Biochemical journal 1981-02, Vol.193 (2), p.411-418
• Main Authors: Madar, D A, Hall, T J, Hiskey, R G, Koehler, K A
• Format: Article
• Language: English
• Subjects: Animals; Calcium - metabolism; Cattle; Epitopes - immunology; Isomerism; Kinetics; Magnesium - metabolism; Manganese - metabolism; Protein Conformation; Prothrombin - immunology; Prothrombin - metabolism
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj1930411

Rabbit anti-(bovine prothrombin fragment 1) antibodies were fractionated by using fragment-1 affinity chromatography in the absence of metal ions, and showed an absolute requirement for the presence of metal ions in their interactions with bovine fragment 1 or prothrombin. These antibodies were employed to evaluate both the rate constants for a protein conformation change and the equilibrium metal-ion binding to isolated bovine fragment 1 and intact prothrombin. The close similarity of the rates obtained for the conformation change in fragment 1 and those observed in prothrombin indicated that the same process is involved in both proteins and that the non-fragment-1 region of the prothrombin has essentially no effect on this process in the fragment-1 region. Equilibrium metal-ion-binding studies indicate that the details of the metal-ion-binding process in fragment 1 and prothrombin are essentially the same. We conclude that the metal-ion-binding behaviour of the fragment-1 domain of intact prothrombin is identical with that of isolated fragment 1.