pKa values of hyodeoxycholic and cholic acids in the binary mixed micelles sodium-hyodeoxycholate-Tween 40 and sodium-cholate-Tween 40: Thermodynamic stability of the micelle and the cooperative hydrogen bond formation with the steroid skeleton
For bile acids HD and C pKa values increase in mixed micelles with Tween 40. Increase of ΔpKa of HD and C related to pKa of free HD and C is a measure of mixed micelles stability. H-bonds between steroids OH-Tween 40 polyoxyethylene groups: aggregate stability. Cooperative hydrogen bond formation between HD and Tween 40.