Figure 1
Transition of endothermic micellar breakdown of a high prevalence BA to exothermic with cooling, and cessation of micellar breakdown of STC at 25 °C. Table showing the concentrations of bile acids (left) and Cholic acid conjugates (Right, dark blue background) measured by LC MS/MS in the bile of rats (A) Enthalpograms representative of micellar breakdown of STC at the indicated temperatures. Note the progressive reduction in magnitude of endothermic reaction enthalpy (ΔH) to exothermic at 15 C. This is shown as an average of 3 experiments. (B) Change in enthalpy (ΔH) from the initiation of micellar breakdown (start, upward triangles) till equilibrium was reached (end, downward triangles). Note that the two line intersect at 25 C (yellow star) and that the equilibrium becomes progressively exothermic, supporting the contribution of hydroxyl groups in stabilizing micellar structure. (C) The Gibbs free energy and entropy of the titration curves at various titration temperatures. The minimum at 25 °C indicates favorable conditions for STC micelles, which correspond to a near athermal titration and a large reduction in CMC. (D) Cryo-TEM images showing PBS and solutions of STC at 50 mM and 500 µM in PBS analyzed at 25 °C. Note the presence of micelles at both STC solutions. Autocorrelation functions collected from STC at 7 mM (blue), 5 mM (red) 3 mM (yellow), and 2 mM (green) in PBS at 37 °C (E) and 25 °C (F).
