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Purification and functional characterization of a novel tyrosinase (diphenolase) inhibitory peptides prepared from Solunum tuberosum peels protein via enzymatic hydrolysis

El-Sayed, Sanaa T., Al- Azzouny, Rehab A., Ali, Ola S.
Biocatalysis and agricultural biotechnology 2019 v.17 pp. 331-338
L-dopa, byproducts, catechol oxidase, enzymatic hydrolysis, enzyme activity, enzyme inhibition, enzyme inhibitors, fractionation, hydrolysates, hydrolysis, lettuce, molecular weight, monophenol monooxygenase, pH, peptides, potato peels, potatoes, proteinases, reversed-phase high performance liquid chromatography, temperature, therapeutics, ultrafiltration
The present study was designed to prepare a novel tyrosinase inhibitory peptides from Solunum tuberosum (potato) peels (by-product of potato processing). Isolated protein was hydrolyzed by immobilized lettuce protease at pH 10 to produce a potato hydrolysate (peptides) with the highest tyrosinase inhibitory activity than that of the parent protein. For maximum production of peptides, hydrolysis process including incubation temperature and protein concentration per reaction mixture was optimized. Separation of potato hydrolysate by ultrafiltration provides three fractions (F1, F2 and F3) of which F1 (< 10 KDa) showed the strongest tyrosinase inhibitory potency (12.07 + 0.0 µg KE/µg peptides). F1 was further fractionation by three reverse phase-high performance liquid chromatography (RE-HPLC) to a finally single tyrosinase inhibitory peak. Collected peak (potato tyrosinase inhibitor) was further analyzed using HPSEXC chromatography confirmed its purity with molecular weight 485.98 kDa. It had superior tyrosinase (diphenolase) inhibitory potency compared to those of the original protein (990.44 µg KE/µg peptides). The Km and Vmax values of tyrosinase activity towards L-DOPA in presence of potato inhibitor decreased with increased the tyrosinase concentrations. The kinetic studies revealed that potato inhibitor defined as uncompetitive type. The results of this study suggested that potato peels are a good source of natural tyrosinase inhibitory peptides which exhibit therapeutic potential for curing or preventing some diseases.