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Thromb Haemost 1985; 53(01): 019-023
DOI: 10.1055/s-0038-1661228
Original Article
Schattauer GmbH Stuttgart

A Kinetic Model Describing the Interaction of Bovine Prothrombin Fragment 1 with Calcium Ions[*]

Charles W Kabis
1   The Chemistry Department, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
,
Martha M Sarasua
1   The Chemistry Department, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
2   The School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
,
Karen E Gottschalk
1   The Chemistry Department, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
2   The School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
,
Carolyn D Bourne
1   The Chemistry Department, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
,
Lee G Pedersen
1   The Chemistry Department, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
,
Craig M Jackson
3   The Department of Biological Chemistry, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri, USA
,
Richard G Hiskey
1   The Chemistry Department, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
,
Karl A Koehler
4   The Biochemistry Department, Case Western Reserve University, School of Medicine, Cleveland, Ohio and Department of Surgery, Cleveland Metropolitan General Hospital, Cleveland, Ohio, USA
› Author Affiliations
Further Information

Publication History

Received 08 February 1984

Accepted 19 October 1984

Publication Date:
18 July 2018 (online)

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Summary

A kinetic model is derived for the interaction of bovine prothrombin fragment 1 with calcium ions. The model requires binding of a minimum of two calcium ions for induction of the observed biphasic fluorescence decrease as a function of time. The model is shown to be consistent with experimental kinetic and equilibrium data by fitting theoretical curves for the biphasic fluorescence change to the data through exact solution of the nonlinear differential rate equations derived from the model. The rate constants for the binding of these two required calcium ions are calculated from the solutions as best fit parameters. The thermodynamic equilibrium constants, K1 and K2, for the binding of these two calcium ions are calculated from ratios of the forward and reverse rate constants as 0.6 × 104 and 5.4 × 104, respectively. Thus, the model correctly predicts positively cooperative calcium ion binding for at least the two calcium ions required to induce fluorescence quenching.

Key words

Prothrombin - Fluorescence - Calcium - Kinetics

* This work was supported in part by National Institutes of Health Grants HL-20161 and HL32159, and by a grant from the Cuyahoga County Hospital Foundation.