Barley α-Amylase

 

The barley α-Amylase Isozyme is a monomeric enzyme found barley, Hordeum vulgare. There are similar amylases found in other plants, as well as animals and bacteria. The important roles of this particular α-Amylase in barley are general catabolism, as well as during seed germination. When seeds are deposited on the ground increases in temperature and humidity triggers the embryo to produce phytohoromones, one of these is giberellic acid, which induces synthesis of α-Amylase. This enzyme then begins breaking down starch, and similar large energy storage polymers, into smaller carbohydrates that can be used by the sprouting plantlet. This α-Amylase catalyzes the endohydrolysis of 1,4-alpha-D-glucosidic linkages in oligosaccharides and polysaccharides, yielding smaller carbohydrates that can be used as an energy source. This process is thermodynamically favorable because of the large increase in entropy (ΔS) associated with the breakdown of a large polymer into smaller subunits.

   

This enzyme forms a structure called a TIM barrel which can be clearly seen as the protein moves upon clicking the first then the second button. The third button shows where ligand has bound (rendered in spacefill). The active site of the enzyme, and the three catalytic residues; Asp180, Glu205, and Asp291 are located in it, along with a Calcium ion which together form the catalytic domain of the enzyme. These can be viewed by clicking on the 4th button.

Summary

 

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