Prothrombin-membrane interaction. Effects of ionic strength, pH, and temperature

Robert M. Resnick, Gary L. Nelsestuen

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

The effects of ionic strength, pH, and temperature on three separate aspects of prothrombin-phospholipid membrane binding were studied. The three parameters include a calcium-dependent protein transition, a calcium-membrane interaction, and, finally, the binding of calcium-saturated protein to a calcium-saturated phospholipid membrane. The results are consistent with calcium binding to carbonyl groups in the protein and to phosphate in the phospholipids. These interactions show the expected pH profiles and sensitivity to ionic strength. Temperature effects indicate a small negative enthalpy change for each process. The binding of calcium-saturated protein to calcium-saturated membrane shows very little variation between pH 6 and pH 9, is accompanied by no detected enthalpy change, and is relatively insensitive to ionic strength. These latter results indicate that ionic calcium bridging between the protein and membrane is not important. A chelation model for prothrombin-membrane binding is proposed where the two interacting species have no net charge; ligands on the protein complete the coordination sphere of membrane-bound calcium and vice versa.

Original languageEnglish (US)
Pages (from-to)3028-3033
Number of pages6
JournalBiochemistry
Volume19
Issue number13
StatePublished - 1980

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