Plant Aspartic Proteases for Industrial Applications: Thistle Get Better

Abstract

Plant proteases have a number of applications in industrial processes including cheese manufacturing. The flower of the cardoon plant (Cynara cardunculus L.) is traditionally used as a milk-clotting agent in protected designation of origin cheeses made from goat and sheep milk. Plant-derived rennets are of particular importance to consumers who wish to eat cheeses that are produced without harming any animals. In this review, we have highlighted the importance of plant proteases, particularly aspartic proteases, in industrial processes, as well as exploring more fundamental aspects of their synthesis. We have also reviewed and discussed the production of these enzymes using sustainable and cost-effective alternative platforms.

Mechanisms controlling plant proteases and their substrates

“…In animal systems, proteases have extensively attracted researchers' attention, mainly due to their functions in cell death and disease, and as potential drug targets for biomedical applications. In addition, diverse proteases serve as research tools and are useful enzymes in various industrial applications (116,117). In contrast, our current knowledge of the mechanisms that regulate plant protease activity remains scarce, as is the functional understanding of the cleavage of their substrates.…”

Development and Optimization of an Enzyme Immunoassay to Detect Serum Antibodies against the Hepatitis E Virus in Pigs, Using Plant-Derived ORF2 Recombinant Protein

“…This demonstrates one of the advantages of plant expression systems: their ability to perform eukaryotic post-translational modifications. This and other advantages, such as safety, scalability, and low-cost production, have made plants a viable alternative to other expression systems [ 62 ]. The limitations of plant expression systems, such as proteolytic degradation of recombinant proteins and product heterogenecity due to the glycosylation pattern, have been overcome using different methods [ 63 , 64 , 65 , 66 ].…”

Plant Milk-Clotting Enzymes for Cheesemaking

“…For example, cardosin A accumulates more in the upper part of the C. cardunculus flower, in the protein storage vacuoles of the stigmatic papillae, while cardosin B is distributed outside the cell wall and in the lower part of the pistil [ 113 ]. The concentration of cardosins increase with the senescence of the flower and the MCA of the extracts may depends on the plant ecotype used [ 113 , 114 ].…”

“…For example, cardosin A accumulates more in the upper part of the C. cardunculus flower, in the protein storage vacuoles of the stigmatic papillae, while cardosin B is distributed outside the cell wall and in the lower part of the pistil [ 113 ]. The concentration of cardosins increase with the senescence of the flower and the MCA of the extracts may depends on the plant ecotype used [ 113 , 114 ]. To reduce the variability on composition, the extraction/purification techniques such as “salting out” (i.e., the precipitation of proteins in solution by adding ammonium sulphate) coupled to chromatographic methods (for the subsequent purification of the desired enzyme) could be applied.…”