Abstract: An amino acid ionic liquid (AAIL), 1-ethyl-3-methylimidazolium 1-aminopropane-1,3-dicarboxylic acid salt ([C2mim][Glu]), was synthesized by the neutralization method from 1-ethyl-3-methylimidazolium bromide ([C2mim]Br). The binding behavior of α-lactalbumin (α-LAB) with [C2mim][Glu] and [C2mim]Br was evaluated by affinity capillary electrophoresis and fluorescence quenching method. The binding constants of both α-LAB-[C2mim][Glu] and α-LAB-[C2mim]Br were in the order of magnitude of 106 L/mol, with the former being higher than the latter, and the binding ratios were approximately 1:1. This research may provide some references for further studies aimed to understand the mechanism behind α-LAB-ionic liquid interaction and develop an efficient and environment-friendly extraction system for α-LAB.

Key words: α-lactalbumin (α-LAB), amino acid ionic liquids (AAIL), affinity capillary electrophoresis (ACE), binding constant, fluorescence quenching method