Purification of a novel monophenolase inhibitory peptides prepared from Vicia faba pods protein via enzymatic hydrolysis

The aim of the present study was to prepare novel monophenolase inhibitory peptides from Vicia faba (broad bean) pods. Isolated protein was hydrolysed by immobilized protease at pH 10. For maximum production of hydrolysate (peptides), an optimized hydrolysis process, including incubation temperature and protein concentration, was established. Broad bean peptides had higher tyrosinase inhibitor potency than that of the parent protein. They were fractionated by ultrafiltration into three fractions: F-1, F-2, and F-3. With high monophenolase inhibitor potency, F-2 was further fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC) three times, followed by high-performance size-exclusion chromatography (HPSEXC) to finally achieve a single peak, confirming its purity with a molecular weight of 26.102 kDa. It had superior monophenolase inhibitor potency compared to that of the original protein. The Michaelis-Menten constant (Km) values of tyrosinase activity toward L-tyrosine in the presence of a broad bean monophenolase inhibitor increased when its concentration increased, while the maximum velocity (V-max) value was unchanged. The monophenolase inhibitor exhibited a competitive type of inhibition. The results of this study suggest that broad bean pods are a good source of monophenolase inhibitory peptides, which exhibit therapeutic potential for curing or preventing some diseases.