Introduction: Carica papaya or tree melon is a plant native to the tropical regions of America. Papain proteinase is an enzyme that is extracted from the juice of unripe papaya fruit. This enzyme has proteolytic function with cysteine protease activity from endolytic plant. Papain is obtained by collecting papaya juice. After this juice is dried, it is purified in order to purify it. Papain is widely used in hydrolysis of short chain peptides, proteins, esterified amino acid and amide bonds, drug production and food proteolysis. This enzyme has been discussed both biologically and industrially, papain. This enzyme has proteolytic function with cysteine protease activity and is obtained from unripe green papaya juice. Papain grows in all tropical regions and in all seasons; Because it is resistant in a wide range of Ph and temperature. This enzyme breaks down organic molecules made of amino acids, known as polypeptides. This enzyme is used in industries: food, pharmaceutical, leather, meat, detergents, etc.
Structure: Papain proteinase is a single-chain protein. Protein folding and conformation is influenced by the hydrophobicity of papain with the outer hydrophilic core interacting with water and stabilizing the inner hydrophobic core in the tertiary structure. The protein is stabilized by three internal disulfide bridges that bring the molecule together along these bridges, creating a strong interaction between the side chains that contributes to the stability of the enzyme. The papain molecule has a second fully alpha sheet and a second antiparallel beta sheet. Hydrophobic interactions have the greatest effect on protein structure and hydrophobic amino acid side chains. In general, it can be said that the enzyme is more stable in hydrophobic solvents.
Function: This enzyme specifically binds to peptides containing positively charged amino acids, mainly lysine, arginine, and phenylalanine residues. Papain proteinase converts proteins into polypeptides and dipeptides. In the active site of this enzyme, there are three amino acids Cys, His and Asp. This enzyme attacks inside the peptide chain that has a free N-terminal. The mechanism by which it cleaves peptide bonds involves deprotonation of Cys25 by His159. Asp175 helps to orient the imidazole ring of His-159 to enable this deprotonation. Although these three amino acids are far apart in the chain, they are close together due to their folded structure.
Application: Proteinases convert proteins into polypeptides and peptides. This feature is widely used in various industries. Among the uses of papain proteinase, we can mention: food industry, health care, pharmaceutical and medicine, drug design, detergent and textile industry.
One of the uses of papain is in pharmaceuticals and medicine. This fruit is rich in antioxidants. Among the effective properties of papaya fruit are increasing blood platelets, treating menstrual pains, activating growth hormones, regenerating muscle tissues, treating fungal infections, treating throat disorders, preventing arthritis, increasing heart health, treating wounds, relieving pain and anti-tumor effects.
Methods: Many studies have been done on the function of papain proteinase enzyme on the body. For example, during recent research it has been found that papain can improve athlete's foot fungal infections, or animal studies on wounds have shown that papain-containing ointments can improve wound healing and collagen deposition, and this enzyme can also help indigestion. Relieve patients sensitive to gluten, and in recent studies on cancer mice, it has been shown that papain injection is effective in the process of tumor healing.
Results: This review provides an overview of the structure and function of papain. Papain plays a vital role in pharmaceutical food, health care industry, detergents, cosmetics, textiles and leather. Papain is an inimitable enzyme class and has proteolytic activity with cysteine protease activity from endolytic plants. The source of this enzyme is green papaya juice.
Conclusion: Currently, papain is widely used in various industries because it covers the stages of the biocatalyst cycle. With the advancement of technology, it is now used to treat fatal diseases. In addition, they are investigating more benefits of papain so that it can be used in drug design. It can be hoped that this enzyme can be genetically and chemically modified by protein engineering and recombinant DNA, so that it can be used for ideal biotechnology and industrial applications.