Leather industry proteases used

Many enzymes have been the subject of protein engineering studies, including several that are important in medicine and industry, eg, lysozyme, trypsin, and cytochrome P450. SubtiHsin, a bacterial serine protease used in detergents, foods, and the manufacture of leather goods, has been particularly well studied (68). This emphasis is in part owing to the wealth of stmctural and mechanistic information that is available for this enzyme. 

Proteases are enzymes that break down protein molecules through peptide bond hydrolysis [1]. They are commercially employed in many industrial processes. In foods, proteases have two main applications in the processing of traditional food products and in the processing of new protein-based ingredients called functional foods [2]. Proteases are also used in other industrial segments such as leather industry, pharmaceutical, waste management, and the detergent industry. Currently, microbial proteases make up approximately 40% of total enzyme sales [3, 4]. 

Leather industry uses proteolytic and lipolytic enzymes in leather processing. The use of these enzymes is associated with the structure of animal skin as a raw material. Enzymes are used to remove unwanted parts. Alkaline proteases are added in the soaking phase. This improves water uptake by the dry skins, removal and degradation of protein, dirt, and fats and reduces the processing time. In some cases, pancreatic trypsin is also used in this phase. 

Proteases are used in dehairing and dewooling of leather, and improve its quality (cleaner and stronger surface, softer leather, less spots). Lipases are used in this phase or in bating phase to specifically remove grease. The use of Upases is a fairly new development in leather industry. 

Protease is an enzyme used widely for detergents and dairy production, baking, and also in the pulp, paper, and leather industries. Carbohydrases, primarily amylases and cellulases, are used in starches, textiles, detergents, and the baking industry. Lipases are used in food, pulp, paper, leather, and the organic synthesis industries. 

Recently, a review on commercial proteases has been published stating the wide range of protease application but leather industry is one of the main application areas in it (Li et al., 2013). Although studies on the use of enzymes for various stages of leather processing are numerous, the commercial production and application of enz3mies in the leather industry is limited. In limited commercial enzyme products, the process, called enzyme-assisted process, needs either lime or sulphide in addition to the enzyme. All the commercial enzymatic products with their company name are summarized in Table 9.6. 

Processes carried out at a pH of 7-9 represent the most efficient use of this type of enzyme. The first industrial process involving this type of protease was in the bating of hides to remove the debris from the skin after liming, and to impart softness and air exchange to the finished leather. Although pancreatic bates are still in general use proteases derived from Aspergillus flavus-oryzae and Bacillus subtilis now supple ment them. 

Industrial applications represent more than 80% of the global market of enzymes. A distinction should be made between those cases in which the enzymatic conversion of the raw material into the product is the key operation and those in which the enzyme is used as an additive to modify certain functional property of the product. In the first case the enzymatic reaction is carried out in a controlled environment at optimized conditions with respect to the catalytic potential of the enzyme, while in the second case conditions for enzyme action are not specified to optimize its activity and sometimes not even controlled. Examples of the first case are the production of high-fructose syrups with immobilized glucose isomerase and the production of 6-aminopenicillanic acid from penicillin G with immobilized penicillin acylase examples of the second case are the use of fungal proteases in dough making and the use of pancreatin in leather bating. Most conventional uses of enzymes refer to... 

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