Probing deep into the binding mechanisms of folic acid with α-amylase, pepsin and trypsin: An experimental and computational study

•Binding interactions exist between folic acid and three digestive enzymes.•FA is able to reduce the enzymatic activity of α-amylase, pepsin, and trypsin.•Noncovalent interactions stabilized the digestive enzymes-folic acid complexes.•There is a major binding site of α-amylase, pepsin, or trypsin with folic acid.

The inhibitions of folic acid (FA) towards three digestive enzymes, including α-amylase, pepsin and trypsin, were examined. The results showed that FA was able to reduce the enzymatic activity of α-amylase, pepsin, and trypsin by the formation of FA-enzyme complexes. The fluorescence spectral data indicated that the binding of FA with α-amylase, pepsin and trypsin resulted in strong fluorescence quenching of Tyr and Trp residues by hydrophobic interactions, hydrogen bonding and electrostatic interactions. To identify the precise binding sites of FA on α-amylase, pepsin and trypsin, the molecular modeling studies were also performed in this work. These investigations may constitute meaningful work for further advances in the mechanisms behind the interactions between FA and digestive enzymes.