Affect of ph on the Reaction Rate of Enzymes

6 Pages • Essays / Projects • Year Uploaded: 2021

This laboratory explores the affects pH has on a reaction rate. The reaction studied was the breakdown of hydrogen peroxide catalyzed by the enzyme peroxidase. Three trials were run at pH levels of 6, 7 and 8. It was hypothesized that the reaction would run very quickly at a pH of 7, since that is the normal condition of cells where peroxidase is found. It was further hypothesized that the reaction would slow significantly at pH’s of 6 and 8 since they are not within the normal pH range of a cell. All hypotheses were found to be correct. Altering the pH of the solution into which the enzyme was added slowed the reaction rates significantly. The breakdown of peroxide occurred most rapidly in the solution with a pH of 7. The slower reaction rates are due to the addition of hydrogen or hydroxide ions which bond to positively or negatively charged side chains of the amino acids within the protein. Since the side chains are bonded to ions in solution, they are unavailable to bond with each other. This lack of bonding amongst the side chains affects the tertiary structure of the protein, changing its shape. The shape change makes many of the peroxidase molecules unavailable to correctly bind with the hydrogen peroxide substrate, thus slowing the rate of the reaction.

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