Enzymes - Viviana Veber T.A. Mona L March 22, 2011 BIO 1510...

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Viviana Veber T.A. Mona L March 22, 2011 BIO 1510 Enzymes Introduction: In the living organisms, reactions occur every second. Two prime examples of these reactions are dehydration and hydrolysis. Dehydration is a process where complex molecules are synthesized from smaller molecules by the removal of water. Hydrolysis is the opposite process in which complex molecules are broken into simpler molecules by the addition of water. Both processes occur naturally in organisms, but happen at extremely slow rates. Organic catalysis also known as enzymes, are normally proteins, however there have been many enzymes made up of RNA nucleic acid. Enzymes are catalytic proteins, meaning they speed up chemical reactions without being used up or altered permanently in the process. Although various enzymes use different methods, all accomplish catalysis by lowering the activation energy for the reaction, thus allowing it to occur more easily. Enzymes have very specific shapes (conformations). Part of the conformation is the active site of the enzyme, where the actual catalysis occurs. The specific molecule or closely related molecules on which an enzyme functions is known as its substrate. Shape plays such an important role in enzymatic catalysis that often even isomers of a substrate will be rejected. Once the substrate enters the active site, it may begin a process known as induced fit in which the enzyme perfectly conforms to the molecule to allow for more efficient catalysis. Changes in environment can severely impact enzyme catalysis in both negative and positive ways. Each enzyme has specific ranges at which it optimally functions; in general, increasing the temperature will help the reaction along, until the point at which the protein degrades and denatures. Denatured proteins will often return to their original state, after the removal of the denaturing agent, except when they are degraded multiple levels. Without altering the physical integrity of the cell, enzymes can change the rate of a cell’s chemical reaction. Enzymes are never used nor changed in the reaction. Therefore, they can be recycled to break down additional substrate molecules. Being proteins, enzymes have a highly organized structure which dictates its specificity for substrates. The primary structure of an enzyme includes its amino acid arrangement. This arrangement then controls the secondary and tertiary structures, which are intermolecular bonds forming between amino acids and their side chains, creating a three-dimensional conformation. If the shape of the enzyme is denatured or interrupted, then the enzyme will not function properly. Each active site has its own unique enzyme. There is a specific substrate that fits the active site of certain enzymes. Variations in temperature, salt, ion concentration and hydrogen ion concentration may change the active site as well as, the enzyme. Any of these factors could denature the enzyme by the denaturing the protein structure.
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This note was uploaded on 06/13/2011 for the course BIO 1500 taught by Professor Pandolfi during the Winter '08 term at Wayne State University.

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Enzymes - Viviana Veber T.A. Mona L March 22, 2011 BIO 1510...

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