Papain sources

Figure 10-24 Effect of Immobilizing on the pH Optimum of Papain. Source From H.H. Weetall, Immobilized Enzymes and Their Application in the Food and Beverage Industry, Process Biochem., Vol. 10, pp. 3-6, 1975.

Enzyme Nomenclature. The number of enzymes known exceeds two thousand. A system of classification and nomenclature is required to identify them unambiguously. During the nineteenth century, it was the practice to identify enzymes by adding the suffix -in to the name of their source. Names such as papain, ftcin, trypsin, pepsin, etc, are still in use. However, this system does not give any indication of the nature of the reaction catalyzed by the enzyme or the type of substrate involved. 

Until about 1950, the predominant method of producing industrial enzymes was by extraction from animal or plant sources by 1993, this accounts for less than 10%. With the exception of trypsin, chymosin, papain [9001 -73-2J, and a few others, industrial enzymes are now produced by microorganisms grown in aqueous suspension in large vessels, ie, by fermentation (qv). A smaH (5%) fraction is obtained by surface culture, ie, soHd-state fermentation, of microorganisms (13). 

The greatest variety of industrial enzymes are presently derived from microbial sources, with a lesser diversity coming from plant and animal sources 34), Enzymes derived from plant sources and which are used extensively in the food industry include papain, bromelain, ficin, and amylases. Animal enzymes of economic importance include trypsins, lipases, and gastric proteases. 

Another major application of the plastein reaction is nutritional improvement of proteins by the incorporation of limiting amino acids (8). A plastein containing approximately 7% methionine was produced from soy protein hydrolyzate and L-methionine ethyl ester in the presence of papain. This material was shown to be utilized as a source of methionine in the rat, producing a PER of 3.38 when incorporated into soy protein diets to give a methionine level of 2.74% of protein. 

This text is a good source of information on the chemical mechanisms underlying the different modes of peptidase catalysis. Three important enzymes are covered subtilisin, a serine endopepti-dase papain, a cysteine endopeptidase and chymosin, an aspartic endopeptidase. 

Source. Enzymes for food applications come from all three kingdoms plant, animal, and microbial. Traditionally used plant and animal enzymes are the plant proteases such as papain, ficin and bromelain, plant amylases from malt, and animal rennin which is used in cheese manufacture. Microbial cells are the usual and most promising future source of industrial enzymes. Estimates of the number of microorganisms in the world tested as potential sources of enzymes fall around 2% with only about 25 organisms, including a dozen or so fungi, currently used for industrial enzymes. 

Some of the traditionally used industrial enzymes (e.g., rennet and papain) are prepared from animal and plant sources. Recent developments in industrial enzyme production have emphasized the microbial enzymes (Frost 1986). Microbial enzymes are very heat stable and have a broader pH optimum. Most of these enzymes are made by submerged cultivation of highly developed strains of microorganisms. Developments in... 

An example of an enzyme you may have used is papain, found in papayas, pineapple, and other plant sources. This enzyme catalyzes a reaction that breaks down protein molecules into free amino acids. Papain is the active ingredient in many meat tenderizers. When you sprinkle the dried form of papain on moist meat, you activate the papain so that it breaks down the tough protein fibers in the meat, making the meat more tender. 

The most widely used animal enzyme is chymosin which is used for milk clotting in the production of cheese. Well known plant enzymes include papain, bromelain and cereal malt. Microbial enzymes have been used in the fruit and cereal processing industries since the 1950 s and offer a less expensive source. Eor example, chymosin (a relatively expensive enzyme found in the stomach of calves) have been replaced by the microbial rennet in the production of cheese. 

Proteases such as a-chymotrypsin, papain, and subtilisin are also useful for regioselective hydrolytic transformations (Scheme 2.40). For example, while regio-selective hydrolysis of a dehydroglutamate diester at the 1-position can be achieved using a-chymotrypsin, the 5-ester is attacked by the protease papain [260]. It is noteworthy that papain is one of the few enzymes used for organic synthetic transformations which originate from plant sources (papaya). Other related protease preparations are derived from fig (ficin) and pineapple stem (bromelain) [261]. 

The preparation of hydrolysates from a variety of meat sources has been considered, including bovine lung and bovine rumen (Webster et al., 1982) and mechanically deboned poultry (Smith and Brekke, 1985). Of the enzymes investigated, pepsin, papain and neutrase appear to be the most useful. 

Papaya Carica papaya) belongs to the family Caricacea which includes four genera and more than 20 species. The distribution can extend from latitude 32 north to 32 south where the weather is warm and humid and the elevation is less than 300 m above sea level. The fruit is commonly eaten fresh but can be cooked when immature or used in preserves, sauces or pies. The papaya in India is used in canning, candying and pickling as well as fresh consumption. It can be used as a source of papain for meat tenderizing and it is also an excellent source of vitamin C (Arriola et aL, 1980). 

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