Alakolange Gedara Achala Wimukthika Alakolanga

• The popularity of plant-based proteins, especially legumes has experienced a remarkable surge in recent years, due to the heightened awareness health benefits, concerns on animal welfare, environmental sustainability, and advancements in food technology. Apart from their nutritional value, many of the encrypted peptide sequences have shown remarkable bioactivities. However, most of the legume crops consumed worldwide are not evaluated for protein profile and bioactive potential, except for soya beans, peas, and lentils. The lack of scientific evidence has become a major barrier in successful utilization of these legumes. Also, there are many chemical and physiological barriers which limit the protein digestion such as protease inhibitors and complex structural diversity. So, this study was planned to evaluate the amino acid profile, presence of bioactive peptide sequences and improving the digestibility of proteins from common legumes cultivated in Sri Lanka, including pigeon pea-Cajanus cajan, green gram- Vigna radiata, cowpea - Vigna unguiculata, black gram - Vigna mungo and horse gram- Macrotyloma uniflorum. Extraction with acid, alkaline, salt, alcohol and TRIS buffers were compared for the yield and the diversity of protein profile. Digested protein extracts with trypsin, chymotrypsin and pepsin were analysed by LC-ESI-MS. Peptide sequencing was performed with PEAKS software to identify proteins, post-translational modifications, and amino acid profile. The peptide fragments identified from trypsin, pepsin and chymotrypsin hydrolysates were screened with different in-silico approaches and in vitro bioassays. Also, the effect of domestic processing methods including soaking, gemination, boiling and roasting on the digestibility of green gram proteins was evaluated. Results showed that the alkaline extraction is effective in extracting an optimum protein yield with most diverse and balanced protein profile, comprising storage, enzyme, and other functional proteins. Most of the cultivars tested show similar storage protein profiles, but there were significant differences in functional proteins important in abiotic stress management. Also, seed storage proteins show extensive post-translational modifications, which serves as another level of protection and functionalities such as dormancy release and metabolic resumption. They also have balanced essential amino acid profile, except for Methionine (M) and tryptophane (W). All legumes exhibited significant potential in antioxidant and antibacterial properties, and trypsin mediated digestion is more successful in generating bioactive peptides. Boiling and roasting enhanced the digestibility of legume proteins, which can be attributed to the removal of protease inhibitors, unfolding of globular storage proteins and alterations in secondary structures into less ordered conformations.