Thromb Haemost 1978; 40(02): 350-357
DOI: 10.1055/s-0038-1648668
Original Article
Schattauer GmbH Stuttgart

The Binding of Calcium Ions to Bovine Factor X by Rate Dialysis

Robert H Yue
The Cardiovascular Research Division, Institute of Rehabilitation Medicine, New York University Medical Center, New York, New York/10016, USA
,
Menard M Gertler
The Cardiovascular Research Division, Institute of Rehabilitation Medicine, New York University Medical Center, New York, New York/10016, USA
› Author Affiliations
Further Information

Publication History

Received 28 September 1977

Accepted 28 December 1977

Publication Date:
12 July 2018 (online)

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Summary

The binding of Ca+2 to bovine factor X (molecular weight of 74,000) (Yue und Gertler 1977) was studied by the technique of rate dialysis and with the use of 45Ca+2. The binding data are consistent with a model of sequential mechanism. One mole of Ca+2 binds to the glycoprotein with a dissociation constant of 5.2 × 10-5 M and an additional 39 ± 4 moles of Ca+2 bind to this zymogen with a dissociation constant of 3.7 × 10-3M. The binding of the high affinity Ca+2 causes a functionally significant change in the zymogen, and (calcium) (factor X) complex is the real substrate in the activation process by the protease in Russell’s viper venom.