Cooperative proton and calcium binding by sarcoplasmic reticulum ATPase

Citations of this article
Mendeley users who have this article in their library.


The classic work on binding of calcium to CaATPase is analyzed by an objective non-linear least squares procedure of 74 data points over six pH values. Binding of two calciums to the basic form of the sites occurs with an equilibrium stability constant product of log K1K2 = 13.2. Owing to competition from protons, this value drops in acidic and neutral solutions, becoming, for example, 11.9 at pH 6.8. Binding of the two calciums is so strongly cooperative that its extent is difficult to estimate reliably; there is very little of the one calcium species. Two protons are also bound cooperatively to the calcium sites. In solutions of calcium free protein, at pH < 7.6 the predominant species holds two protons at the calcium sites, while at greater pH the dominant species bears no protons; there is very little of the intermediate one proton species. The analysis also reveals the likely presence of small, less than statistical, amount of a ternary complex bearing one calcium and one proton. © 1992.

Author supplied keywords




Martin, R. B. (1992). Cooperative proton and calcium binding by sarcoplasmic reticulum ATPase. FEBS Letters, 308(1), 59–61.

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free