In silico analysis of the large and small subunits of cereal RuBisCO as precursors of cryptic bioactive peptides

Abstract

Ribulose-1,5-bisphosphate carboxylase (RuBisCO) is a plant metabolic enzyme and the most abundant protein on earth, but remains largely underutilized in the food system. Bioinformatics analysis was conducted to evaluate the prospects of RuBisCO from widely cultivated cereals (rice, barley, wheat, oat, sorghum, corn) as sources of bioactive peptides, and results were compared to commonly consumed proteins. The large and small RuBisCO subunits were found to contain several bioactive peptides with biological functions relevant to the management and treatment of diabetes, cardiovascular and neurodegenerative diseases, specifically inhibition of angiotensin converting enzyme and dipeptidyl peptidase-IV, antioxidative property and activation of ubiquitin-mediated proteolysis. Due to high sequence homology, there was negligible difference in occurrence frequency of bioactive peptides within large RuBisCO subunits unlike small subunits, which produced more diverse profiles of bioactive peptides among the cereals. The cereal RuBisCO displayed similar or better prospects as other food proteins except milk proteins, thereby providing cheaper and sustainable precursors of bioactive peptides. Simulated enzymatic hydrolysis of RuBisCO subunits indicated that thermolysin and papain had preferred cleavage patterns for releasing the cryptic peptides compared to gastrointestinal proteases. These findings will contribute towards utilization of RuBisCO as alternative sources of peptide-based nutraceuticals for human health promotion.