Amylases — Significance of Determination of their Activity
Department of Biochemistry, Faculty of Science, Palacký University, Olomouc
α-Amylases (EC 188.8.131.52), catalyzing the hydrolysis of α-1,4-D-glucan linkages in starch, are widely distributed in nature, being found in bacteria, plants and animals. Starch is the most extensively used polysaccharide in the diet of the Western world. Starch digestion occurs primarily in the small intestine, where two families of degradation enzymes are found. The first family is introduced into the intestinal lumen and is represented by α-amylases – salivary and pancreatic. Members of the other family (including disaccharidases) are immobilized on the brushborder membrane. Amylase activity assays in blood serum are useful as a diagnostic tool, because markedly elevated serum amylase levels are associated with pancreatitis. There are two most common procedures for the determination of α-amylase activity: amyloclastic and saccharogenic. Many other methods have been introduced, in which either soluble or insoluble chromogenic substrates for α-amylase are used. Recently, a biosensor for α-amylase activity assay was constructed, based on the determination of α-amylase-generated maltose using a peroxide electrode with glucose oxidase, α-glucosidase and mutarotase immobilised on a cellophane membrane. The biosensing method offers a great advantage over traditional spectrophotometry because it is highly sensitive and there is no interference of coloured compounds. Some plants, particularly wheat and beans, contain specific inhibitors of animal α-amylase. The use of these inhibitors can help to improve carbohydrate tolerance in diabetics and aid in weight control. The inhibitors may also found application in imparting pest resistance to crop plants.
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