Interactions of gemini surfactants with two model proteins: NMR, CD, and fluorescence spectroscopies

► Cationic gemini surfactants do not interact with RNase A and HEWL at acidic pH. ► Hydrogen exchange NMR indicated that the stability of RNase A is lowered by about 1 kcal mol−1. ► At alkaline pH, RNase A and HEWL do interact with gemini surfactants. ► Three different Protein Gemini complexes are formed including large aggregates.