Applications of Papain in Various Fields

Life Sciences Industry

1. Papain is widely used in cell separation procedures and has been proven to be more efficient and less destructive than other proteases in certain tissues. For instance, papain can be used to isolate viable, morphologically intact cortical neurons from postnatal rats. During smooth muscle cell separation, papain can isolate a large number of viable smooth muscle cells without affecting their sensitivity to stimulants.
2. Papain’s partial hydrolysis capability can be used for structural studies of enzymes and other proteins.
3. Papain can be applied in red blood cell serology by modifying the surface of red blood cells, thereby enhancing or disrupting the reactivity of many red cell antigens. It can be used as a supplemental tool for classification, antibody screening, and antibody identification. It also has applications in platelet serology.
4. Papain can be used in enzymatic synthesis of amino acids, peptide chains, and other molecules.
5. Fab and F(ab')2 antibody fragments are useful in experimental systems where the Fc domain is undesirable. In such cases, using antigen-binding fragments (Fab) is more suitable. Papain is employed for the routine preparation of Fab fragments from immunoglobulin G (IgG). Immunoglobulin M (IgM) can also be digested by papain to produce a large number of Fab fragments. Papain cleaves antibodies into two Fab fragments, which retain their antigen-specific recognition, and one Fc fragment. The cleavage occurs above the disulfide bond in the hinge region of the heavy chain and below the disulfide bonds between the heavy and light chains, forming two separate monovalent Fab fragments and a complete Fc fragment. These fragments can be purified through gel filtration, ion exchange, or affinity chromatography. In tissues like lymph nodes and spleen or in peripheral blood preparations, Fc receptor-bearing cells, such as macrophages, monocytes, B lymphocytes, and natural killer cells, can bind the Fc domain of intact antibodies, resulting in background staining in areas not containing the target antigen. The use of Fab fragments ensures that antibodies bind only to antigens and not Fc receptors. These fragments are also useful for staining cells in the presence of plasma since they do not bind complement that can dissolve cells. This precise antigen targeting, as seen in electron microscopy tissue staining, provides greater accuracy in antigen localization.

Healthcare Industry

Papain supports the immune system in cancer therapy by controlling and altering white blood cells involved in immune responses. It reduces swelling and inflammation in joints and the prostate. Raw papaya-derived papain exhibits 90% activity. In 2012, Hitesch et al. studied the enzyme’s effects using agglutination formation and absorbance measurements. They identified enzyme-degrading compounds in the drug levetiracetam and granules with hazardous effects on cell systems. Spectrophotometric and thin-layer analyses of the drug showed favorable results. Papain also possesses antifungal properties. In 2010, Chukwuemka and Anthony reported that papaya could reduce fungal infections responsible for papaya decay. Their investigation of fungi from Rhizopus, Aspergillus, and Mucor demonstrated inhibition zones reducing mycelial growth, statistically showing that papaya could extend shelf life. Papain reduces allergic reactions in leaky gut syndrome by decreasing hydrochloric acid and lowering gelatin intolerance. It has been shown to offer significant pain relief and anti-inflammatory effects in head and tooth pain allergies without side effects. Papain plays a vital role in skin and wound care. In Hawaii and Tahiti, concentrated papain extracts from papaya have been successfully used to treat skin wounds, burns, bedsores, irritation, and rashes. In 2012, Detrich used papain to treat sports injuries and athlete’s foot, reporting recovery within 3-8 days after papain use.

Food Industry

Globally, papain is one of the most researched and widely used enzymes in the food industry. It is used to tenderize meat proteins, particularly myofibrillar and connective tissues. Different concentrations of papain (0.25%, 0.05%, 0.075%, 0.1%) were applied to 5% or 3% levels of chicken leg cuts to improve meat tenderness. Papain at a 0.25% concentration showed significantly improved tenderness at the 3% level compared to the 0% control group. Tenderization was performed on discarded chicken meat using a 0.25% papain solution combined with soaking techniques to enhance its functional properties for effective utilization. Papain also plays an important role as a clarifying agent in the food industry. Since it can break down proteins, it aids in digestion and helps manage indigestion and other digestive and gastrointestinal disorders. Research shows that papain improves the melting and stretching properties of Nabulsi cheese by acting on casein cross-linking, enhancing the use of Nabulsi cheese in various pastries, pizzas, and Kunafa. Papain-treated Nabulsi cheese demonstrated good fiber structure and storage performance, making it an effective solution for high salt-induced melting or stretching issues. Papain is also used as a softening agent in chewing gum.

Conclusion

This article reviews the basic structure, mechanism of action, production, and industrial applications of papain. It is currently one of the most widely applied hydrolytic enzymes on the market with promising market potential. Through recombinant DNA and immobilization technologies, papain has the potential to become an ideal material for industrial applications. By understanding its detailed mechanism and functions, researchers can explore more effective uses of papain, ultimately leading to new functions that meet the growing demands for improving life quality.