Proteases

Biochemistry

Food science

Serine protease

Protease

Enzyme

Hydrolysis

Isoelectric point

Chemistry

As a new food source, Moringa oleifera Lam. leaves containing large amounts of proteins attract increasing attention. This study detected and characterized hydrolytic and milk-clotting enzymes in these leaves. The proteins were examined by proteomics. A total of 3378 proteins were identified, mostly comprising enzymes of carbohydrate and protein metabolism, including 676 hydrolases, 548 oxidoreductases, glycoside hydrolases and proteinases. A serine/threonine-endopeptidase with a molecular mass of 56.146 kDa and an isoelectric point of 5.27 with milk-clotting activity was obtained from M. oleifera leaves by multistage ultrafiltration and anion exchange chromatography, and characterized by ESI mass spectrometry. The milk-clotting activity was inhibited over 95% by chymostatin, which confirmed its chymotrypsin-like serine protease nature. The protease had a milk-clotting activity/proteolytic activity (MCA/PA) activity ratio of 126.76, an optimal pH of 8.0, and an optimal temperature of 65 °C, indicating its potential use for cheese production and in food industry.

Proteomic analysis of Moringa oleifera Lam. leaf extract provides insights into milk-clotting proteases