Antifungal evaluation of cholic acid and its derivatives on Candida albicans by microcalorimetry and chemometrics

Multi-hydroxyl amines including tris(hydroxymethyl)aminomethane (Tris), serinol and ethanolamine were selected as weak affinity ligands using a rapid screening by quartz crystal microbalance (QCM) biosensor. Based on the specific recognition between the ligands and two proteins, lysozyme (LZM) and cytochrome c (Cyt c), a weak affinity chromatography method was developed for specific separation of the two proteins. The frontal analysis results showed that the apparent dissociation constants (K_D) of ligand–protein complexes were all in the order of weak affinity (10⁻⁴ M). By weak affinity columns modified with the three multi-hydroxyl amines individually, LZM and Cyt c were baseline separated as retarded peaks from non-specific protein and each other in a single cycle of loading and eluting. Moreover, the Tris-modified column typically showed the satisfactory repeatability and stability as a new type of weak affinity columns. The present strategy composed of QCM selecting and affinity chromatography separating was promising to extend the variety of weak affinity ligands and develop inexpensive specific affinity methods for separation and purification of multiple proteins on one single column.