Amylase

Amylase - Introduction to Biochemical Engineering 52:108...

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Introduction to Biochemical Engineering 52:108 Fall 2001 Enzyme kinetics lab: Amylase Activity Goals This lab provides a short, one step assay for the enzymes, α -amylase (EC 3.2.1.1). This enzyme breaks down starch (and glycogen, since the two are chemically very similar) by addition of water between glucose units (hydrolysis). The end products of the amylase reaction are shorter polymers of glucose along with the disaccharide maltose, while glucoamylase liberates single glucose sugars. Amylase occurs in mammalian saliva and small intestines and is found in the intestinal tract of most animals. It is also common in plants, where it degrades stored starch and in some bacteria and fungi that attack plants. Glucoamylase occurs only in fungi and selected bacteria. Both types of amylases are industrially significant in the conversion of biomass to refined sugars and sweeteners. Background Corn refiners separate corn kernels into starch, oil, protein and fiber and convert these components into higher value products (CRA, 2001). Major products from the refining industry include corn sweeteners, ethanol and starch (See Figure 1). In addition, corn and byproducts of corn such as, glucose, starch, and corn steep liquor are used as feedstocks for biological reactors which yield organic acids, amino acids, vitamins, and alcohols (Blanch and Clark, 1996). Increasing biological production rates and fermentation yields while maintaining low operating and purification costs will ultimately increase the competitiveness of renewable, corn-based resources with petrochemical methods of commodity production. Figure 1 Corn Refining process (CRA, 2001). One key enzyme which adds value to the corn refining process is α -amylase. In fact, this enzyme is widely used in many industries such as pharmaceuticals, baking, detergents, sewage treatment, natural sweeteners, and animal feeds (Guzman-Maldonado et al. 1995). α -Amylase catalyzes hydrolysis of -1, 4-glucosidic linkage of -1, 4-glucans, such as starch, glycogen, and dextrins. Starch hydrolysis by amylase to produce maltodextrins is one of the major industrial enzyme-catalyzed reactions. Further saccharification requires the addition of glucoamylase (also known as amyloglucosidase). Glucoamylase attacks both exo-(1-4) and branch-point (1-6)- linkages to produce glucose.
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Industrial and academic researchers seek improvements in many of the processes using corn refining and starch conversion by discovery and development of enzyme catalysts. Enzymes that are active at high temperatures and low pH conditions compatable with starch cooking are desirable. Microorganisms from extreme environments have been of particular interest as sources for chemically stable enzymes (Adams and Kelly, 1995). Recently, evaluation of the genome of the hyperthermophilic archaeon, Methanococcus jannaschii , has led to the identification of genes encoding glucoamylase and alpha-amylase. In the Peeples’ lab, these genes have been cloned into
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Amylase - Introduction to Biochemical Engineering 52:108...

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