Isolation, Purification, and Characterization of Proteases From Coriander (Dhaniya) and Carom (Ajwain) Spice Seeds

Proteases are groups of enzymes that can cleave proteins into smaller fragments and maintain homeostasis. They have wide applications in the food processing, detergent, leather, biotechnological, and pharmaceutical industries. The plant-derived proteolytic enzymes are finding increasing clinical and industrial applications. The spice seeds are not explored as sources of raw material for protease production. Carom (Trachyspermum ammi) and coriander (Coriandrum sativum) are common spice seeds as well as medicinal plants used in traditional medicine. This study focuses on the isolation, purification, and characterization of proteases from these spice seeds. The extracted protein after ammonium sulfate precipitation was purified by anion exchange chromatography. Proteolytic activity was studied by azocasein assay for quantitative detection in the presence and absence of inhibitors and metal ions. Protease action was shown in gelatin zymography and BSA digestion. The molecular weights of purified protease from coriander and carom seed are, respectively, around 57 and 52 kDa. Coriander protease is found to be a serine protease in nature, and carom protease is a cysteine protease in nature. The purified proteases were characterized for secondary structure by circular dichroic spectroscopy and FTIR spectroscopy, and confirmed that a major part of the purified proteases is of beta sheet type. Both the proteases showed milk coagulation properties, which can be explored further.