Enzymes groups amylases

Four major enzyme groups are secreted lipolytic, proteolytic, amylolytic, and nucleic acid splitting enzymes. These pancreatic enzymes, some of which are secreted in multipile forms, possess specificities complementary to die intestinal membrane-bound enzymes (Tabic 1). Fresh, uncontsnkinated pancreatic juice is without proteolytic activity because these enzymes am in the form of inactive zymogens. An important fraction of the calcium in pancreatic juice accompanies the enzymes, especially ct-amylase. Human pancreatic juice is moat dose to that of the pig, with high proportions of lipase and a-amylase in comparison with other mammals [1]. Therefore, pig pancreas extract, pancreatin, has up to now been die oreferred enzvme source for therapeutic tuncreas substitution. 

An example of a type I reaction is the use of enzymes such as proteases or amylases in laundry detergents however, this enzyme reaction has caused some controversy in relation to water pollution. Once in solution, the soluble enzyme may digest (i.e., break down) an insoluble substrate such as a blood stain, A major research effort is currently being directed at type II reactions. By attaching active enzyme groups to solid surfaces, continuous processing units similar to the packed catalytic bed reactor discussed in Chapter 10 can be developed. 

The improvement of PC teeth (REIGNING) by EB irradiation at I50°C was checked from the viewpoint of chemical properties for plastic teeth (Sano et al., 2011). Namely, the properties were water absorption, emission of BPA as the soluble product from PC teeth, and content of maltose and mucin as contamination materials on the surface. BPA emission from PC is feared, as BPA has health implications such as endocrine disrupters (Environmental Agency Japan, 1998 Polycarbonate Resin Manufacturing Group [Japan], 2003). Maltose and mucin formed from food by the enzyme (a-amylase) in saliva would adhere to the plastic teeth. The yields or contents of these materials were quantitatively analyzed before and after EB irradiation improvement. 

The purification of some enzymes inactivates them because substances essential for their activity but not classed as a prosthetic group are removed. These are frequently inorganic ions which are not explicit participants in the reaction. Anionic activation seems to be non-specific and different anions are often effective. Amylase (EC 3.2.1.1), for example, is activated by a variety of anions, notably chloride. Cationic activation is more specific, e.g. magnesium is particularly important in reactions involving ATP and ADP as substrates. In cationic activation it seems very likely that the cation binds initially to the substrate rather than to the enzyme. 

An interesting observation is that an enzyme may exhibit different pH activity profiles for various neutral substrates. The explanation of this is that the enzyme binds or transforms such various substrates differently. For example. Taka amylase has different pH optima for long chain amyloses and for low molecular mass substrates. Some specific chemical modifications of the side chains of the enzyme may also alter the pH activity profiles. Kobayashi, Miura and Ichisima (1992) modified the lysine amino groups using bifimctional reagent o-phtalaldehyde, and observed a pronounced shift in the pH-dependence of ohgomaltoside hydrolysis. 

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