The biological significance of proteases

Protease is one of the most important and abundant enzyme systems in the biological industry. It can catalyze peptide bonds in protein macromolecules and hydrolyze them into amino acids, peptides, and peptones, so they are also called peptidases. Protease is widely used in the leather industry, detergent, medicine, food and feed processing industries.

Source of proteases

Proteases come from a wide range of sources, and they are widely distributed in animal viscera, microorganisms, plant stems and leaves, and fruits. Therefore, the sources of proteases include plant sources, animal sources, and microbial sources.

Classification of proteases

Proteases are divided into different types according to different classification methods. According to the way they hydrolyze polypeptides, they are divided into endopeptidases and exopeptidases; according to the optimal pH value of their reaction, they are divided into acid proteases, neutral proteases and alkalis. Protease; according to its active center, proteases are divided into serine proteases, sulfhydryl proteases, metalloproteases and aspartic proteases.

Four major proteases classified by active center

Serine protease: Serine protease is widely present in bacteria, animal pancreas, and molds. Its function is to break the peptide bonds in large molecular proteins and turn them into small molecular proteins. Serine proteases play a very important role in mammals, especially in the digestion, coagulation and complement systems. Serine proteases include four types: trypsin type, chymotrypsin type, staphylococcal type and myxobacteria.

Cysteine proteases: Cysteine proteases are a very important family of proteases, which are widely involved in various physiological processes of plants, such as seed germination, seedling development, stress response, plant tissue differentiation and senescence. Papain and bromelain currently used in large-scale commercial applications are representative of plant-derived cysteine proteases.

Aspartic protease: Aspartic protease is a type of protease molecule carrying phosphorylcholine components, which is widely distributed in a variety of organisms, including viruses, fungi, parasites, mammals and plants, etc., and participates in the body's metabolism And immune regulation. The main representatives are pepsin, renin, cathepsin D, retroviral protease and so on.

Metalloproteases: Metalloproteases refer to proteases containing metal ions in the active center, mainly represented by matrix metalloproteases. Matrix metalloproteinases are a family of endopeptidases whose biological activity depends on zinc ions. At the same time, calcium ions have a certain effect on its activity and stability, and can degrade extracellular matrix. By acting on extracellular proteolysis, it mediates tissue homeostasis and directly participates in multiple system physiological and pathological processes in the body such as cell growth, vascular remodeling, inflammation, tumor invasion and metastasis.