Fluorescence and circular dichroism spectroscopy to understand the interactions between cyclodextrins and α-galactosidase from green coffee beans

The potential of fluorescence measurement and circular dichroism spectroscopy (CDSP) to evaluate the interaction between cyclodextrins (CDs) (CD cavity size, concentration, pH, reaction time, and temperature as well as different side chain groups) and α-galactosidase was evaluated. A strong relationship was observed between α-galactosidase fluorescence intensity and CD cavity size, concentration, pH, reaction time, and temperature as well as different side chain groups. Therefore, it can be concluded that fluorescence intensity measurement can be a promising tool to ascertain β-CD-α-galactosidase interactions. CDSP is also an interesting tool to understand β-CD-α-galactosidase interactions as well as to evaluate the stability of α-galactosidase secondary structure. For instance, CDSP results showed that among three different types of CDs studied (α-CD, β-CD and γ-CD), β-CD promoted the most important α-helix transformation into β-sheet, thus reducing α-galactosidase secondary structure stability and showing the highest inhibitory effect on α-galactosidase fluorescence.