Revisiting the optimal c value for isothermal titration calorimetry

The precision with which the dissociation constant, K(D), can be obtained from isothermal titration calorimetry depends on, among other factors, the concentrations of the interacting species. The so-called c-value the ratio of analyte concentration to K(D)-should fall in the range of 1 to 1000 for reliable K(D) determination. On the basis of simulated, noise-free data, Biswas and Tsodikov [5] recently suggested an optimal c value of 5 to 20. By contrast, we find an optimum at c > 40 on determining the K(D) confidence intervals through simulations containing noise levels typical of state-of-the-art microcalorimeters. (C) 2011 Elsevier Inc. All rights reserved.