Functional characterization of digestive enzymes from Nepenthes khasiana: integration of in silico and in vitro approaches

Carnivorous plants enable their growth in poor nutrient soils with the help of developed adaptation strategies to support survival in extreme conditions. This carnivore syndrome in Nepenthes species can be seen in specialized developed leaf structure, which has several hydrolytic proteins that aid in digesting prey. The present study comprises the functional characterization of digestive proteins from the pitcher of N. khasiana. The proteomics and transcriptomics approaches were applied to characterize and analyze these proteins. The protein quantification by Lowry test and protease assay were performed to examine the quantity and the activity of proteins and enzymes, respectively. Seven digestive enzymes were confirmed from the pitcher’s digestive fluid by liquid chromatography–mass spectrometry (LC–MS/MS). Physicochemical properties, structure predictions, and molecular docking of these proteins with respective substrates were performed using various bioinformatics tools and software. Bioinformatics analysis reveals the critical residue in enzyme–substrate binding. The present work confirm the previous report of the presence of digestive enzymes in N. khasiana digestive fluid and their putative active site residues involved in the substrate interaction. The information from these studies may help comprehend how certain digestive enzymes are engaged in plant defense systems and prey digestion.