Acid Protease

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Protease is a type of trypsin that catalyzes (increases its speed) proteolysis, breaking down proteins into smaller peptides or individual amino acids. They accomplish this by cleaving peptide bonds in proteins by hydrolysis, which is a reaction in which water breaks the bonds. Proteases are involved in many biological functions, including the digestion of ingested protein, protein catabolism (the breakdown of old proteins), and cell signaling. Without other help mechanisms, proteolysis will be very slow, requiring hundreds of years. Proteases can exist in all forms of life and viruses. They have evolved independently many times, and different kinds of proteases can carry out the same reaction through completely different catalytic mechanisms.

Classification

The general term for a class of enzymes that hydrolyze protein peptide bonds. According to the way they hydrolyze polypeptides, they can be divided into endopeptidases and exopeptidases. Endopeptidase cuts the inside of protein molecules to form smaller molecular weights and peptones. Exopeptidase hydrolyzes peptide bonds from the free amino or carboxyl ends of protein molecules one by one, and frees amino acids. The former is aminopeptidase and the latter is carboxypeptidase. According to its active center and optimal pH value, proteases can be divided into serine proteases, sulfhydryl proteases, metalloproteases and aspartic proteases. According to the optimal pH value of the reaction, it is divided into acid protease, neutral protease and alkaline protease. The protease used in industrial production is mainly endopeptidase.

Source

Proteases are widely found in animal organs, plant stems and leaves, fruits and microorganisms. Microbial proteases are mainly produced by molds and bacteria, followed by yeast and actinomycetes.

Acid Protease

Acid protease means that the protease has a lower optimum pH, rather than the acidic group present in the active part of the enzyme. The optimum pH of the acid protease ranges from about 2 (pepsin) to about 4. From the analysis of enzyme activity-PH curve, there are one or more carboxyl groups in the active part of the enzyme. The most thoroughly studied of this type of protease is pepsin.

Figure 1. Protein structure of acid protease.

Inhibitors

The activity of white enzyme is inhibited by protease inhibitors. An example of a protease inhibitor is the serine protease inhibitor superfamily. It includes α1-antitrypsin (protects the body from the excessive action of its own inflammatory proteases), α1-antichymotrypsin (the same is true), and C1 inhibitors (protects the body from excessive protease-triggered complement system Activation)), antithrombin (protects the body from excessive coagulation), plasminogen activator inhibitor 1 (protects the body from insufficient coagulation by preventing protease-triggered fibrinolysis), and neuroserine protease inhibition agent.

Natural protease inhibitors include the alicyclic protein family, which play a role in cell regulation and differentiation. It has been found that lipophilic ligands bound to lipocalin have properties of inhibiting tumor proteases. Do not confuse natural protease inhibitors with protease inhibitors used in antiretroviral therapy. Some viruses, including HIV/AIDS, rely on proteases during their reproductive cycle. Therefore, protease inhibitors have been developed as antiviral means.

Other natural protease inhibitors are used as defense mechanisms. A common example is the trypsin inhibitor found in some plant seeds, the most striking of which is human beings. Soybeans are the main food crops, in which they can prevent natural enemies. Unprocessed soybeans are toxic to many animals, including humans, until the protease inhibitors they contain are denatured.

Reference

1. Southan C.; et al. A genomic perspective on human proteases as drug targets. Drug Discovery Today. 2001, 6 (13): 681–688.