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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