Enzymes are globular protein molecules known commonly as Biological Catalysts. The definition of a catalyst is a substance that can be used to speed up the rate of a chemical reaction while remaining unaffected and unchanged after the reaction. The enzyme's ability to act relies strongly upon the specific shape of the protein molecule, which is coiled into a precise three-dimensional shape. This specific shape is the cleft or depression, which other molecules (substrates) fit into perfectly; this part of the enzyme, is called the active site. The tertiary folding of the polypeptides causes the intricate specific shape of the active site. The substrates are held in the active site by forming temporary bonds with the hydrophilic R groups of the enzyme's amino acids.
Here we have a diagram showing the 'lock and key' theory of enzyme action. sumeetbanker, please do not redistribute this work. We work very hard to create this website, and we trust our visitors to respect it for the good of other students.
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The substrate (key) is shown fitting perfectly into the active site (lock). The substrate binds to the enzyme and forms an enzyme-substrate complex. The reaction then takes place immediately and a substrate is either broken down into two or more products (catabolic reaction) or two or more substrates are bonded to make one product (anabolic reaction). The 'induced fit' theory states that initially the active site is no the perfect shape of the substrate but as it approaches, the shape of the active site changes to make the perfect fit. sumeetbanker, please do not redistribute this project. We work very hard to create this website, and we trust our visitors to respect it for the...