Structural characterization of α‑chymotrypsin after binding to curcumin: Spectroscopic and computational analysis of their binding mechanism

Abstract

Food has a major role in sickness, traditional medicine, and curing. Curcuma longa L. is one of these medicinal plants. Curcuma longa L., a member of the ginger family, grows in tropical regions of Asia. The most application of this medicinal plant is in the food industry for giving color and flavor to food and in Indian Traditional Medicine. The digestive system has a high level of the enzyme such as proteases. Our knowledge of enzymes function and their interactions in the face of different foods is low. The gastrointestinal enzymes need to be regulated in the face of a different condition. In spite of its ability and safety, the impact of curcumin on intestine enzymes has not yet been recognized as an active biological compound. α‑Chymotrypsin (α-Chy) is a digestive enzyme that generated in some special animal such as pancreas of vertebrates. The primary form of this enzyme is a zymogen. α‑Chymotrypsin act in the duodenum. The effect of Curcumin on structure, function, and stability α-Chy was investigated in this study. Different spectroscopy methods, molecular docking, and molecular dynamics simulation were utilized in this investigation. Fluorescence analyses explained that the quenching mechanism was static (The kq were about 1.84, 4.05, 5.57, and 7.73 × 1012 L mol−1. S, respectively). Results from the various experiments showed that Curcumin bound to α-Chy. Spectroscopy methods demonstrated that Curcumin induces a structural change in the α-Chy. After curcumin interaction, β-sheet amount was risen from 32% to 41.4%, whiles the content of α-helix was decreased from 9.2% to 7.2%. Simultaneously, the percent of the β-turn and the random coil was increased. Fluorescence data recorded one binding site. The binding constant, the number of binding sites and thermodynamic parameters (ΔH°, ΔS°, and ΔG°) at four temperatures were calculated. The Van der Waals interactions were found as the main forces, which is in congruence with docking results.