Production, characterization and molecular docking of antioxidant peptides from peptidome of kinema fermented with proteolytic Bacillus spp.

Kinema is an alkaline traditionally fermented soybean product popularly consumed in Sikkim Himalayan region. Kinema was prepared by soybean fermented with different species of Bacillus and analyzed for peptide content, antioxidant activity and consequence of gastrointestinal enzymes (pepsin and pancreatin) on the antioxidant effect. Antioxidant effect was enhanced during soybean fermentation using different starters, which further increased during gastrointestinal digestion. The peptides formed during soybean fermentation were analyzed using LC-MS/MS. Soybean fermented using different starters resulted in the production of some common peptides and a large number of unique peptides, which may affect the functional property of kinema. Peptides having antioxidative amino acids (histidine, phenylalanine, methionine, tryptophan and tyrosine) and significant GRAVY value were selected for their molecular interaction with myeloperoxidase (MPO), a key enzyme responsible for elevated oxidative stress. A peptide SEDDVFVIPAAYPF produced in kinema fermented using Bacillus licheniformis 1G had interaction with four out of five catalytic residues identified in MPO. Kinema prepared using specific starter can produce unique peptides responsible for specific health benefits.