Abstract
Examination of metal ion-dependent effects on the electrophoretic mobility of bovine prothrombin and fragment 1 provides a useful and sensitive method for investigation of conformational processes in these proteins. Utilization of this method reveals a conformational change in bovine prothrombin and fragment 1 which occurs at low metal ion concentrations. Equilibrium dialysis studies indicate that the metal ion-induced shape change occurs concomitant with binding of a single calcium ion/molecule of prothrombin or fragment 1. Mixed metal electrophoretic mobility studies with Mg2+ and Ca2+ have demonstrated the 'synergistic' effect for fragment 1 observed by others. Mixed metal equilibrium dialysis has provided experimental support for this observation and allows us to conclude that two tight Ca2+ sites are not affected by low Mg2+ concentrations and that the third Ca2+ site is also a tight site for Mg2+. Thus, at low Mg2+ concentrations and upon the addition of Ca2+, there are effectively three tight sites; consequently more Ca2+ will bind to the protein at lower total Ca2+ ion concentrations.
Original language | English (US) |
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Pages (from-to) | 4833-4839 |
Number of pages | 7 |
Journal | Journal of Biological Chemistry |
Volume | 261 |
Issue number | 11 |
State | Published - 1986 |
Externally published | Yes |
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology