Hofmeister Anion Effects on Protein Adsorption at an Air–Water Interface

Hofmeister anion effects on adsorption kinetics of the positively charged lysozyme (pH Cl– > F–). This is the result of the strongly polarized halide anion Br– being attracted to the adsorbed protein layer due to strong interaction with local electric field, while weakly polarized anion F– having no ability to penetrate the protein layer. In X-ray reflection studies, we observed that the lysozyme molecules initially adsorbed on the air–water interface have a flat unfolded structure as previously reported in the salt-free solution. In contrast, in the concentrated salt solutions, the lysozyme molecules begin to refold during a...