Partition behavior of bovine serum albumin on homogeneous liquid-liquid extraction with triton X-114 solution by complex formation with pyllogarol red-molybdate reagent

Abstract The present study was conducted to examine the homogeneous liquid-liquid extraction behavior of bovine serum albumin (BSA) using an aqueous solution of Triton X-114 (TX114). We found that the addition of pyrogallol-red molybdate (PR-Mo) to the solution induced the complete extraction of BSA into the TX114-rich phase, though the BSA and PR-Mo could not be extracted selectively into the TX114 phase. To determine the distribution mechanism, photometric titration and circular dichroic (CD) spectroscopy were performed. BSA formed a complex with PR-Mo at a molar ratio of 1:42 in pure water, which shifted to 1:21 in an aqueous solution of TX114, indicating the formation of a ternary BSA-PR-Mo-TX114 complex. The CD spectra revealed that α-helix BSA is dominant in pure water, whereas β-strand BSA is dominant in the presence of PR-Mo. In summary, the structural change induced in BSA by the formation of a ternary complex is a possible switching mechanism of the partitioning behavior in BSA.