Buffer enzymes. The aim of the experiment was to identify the affects of different pH on enzymes.

Authors Avatar by suzy1987 (student)

Chemistry of Life

Roseleen Rahim



Enzymes are globular proteins that contain a specific structure to function. For a reaction to occur they need to come into contact with the substrate molecule to form an enzyme-substrate complex that convert substrate into products.

Enzymes are affected by the increase or decrease in pH which also affect the rate of reaction. Change in pH alters the charge of the amino acids that make up the active site not allowing the enzyme-substrate molecule to form as the substrate no longer attracts to the enzymes active site.

Change in pH changes the shape of the enzyme by breaking the weak bonds on the tertiary structure of the protein molecule causing the enzyme to denature. This occurs due to hydrogen ions (H+) in acids and hydroxyl ions (OH-) in alkaline are attracted to the charges on the amino acids in the polypeptide chain that make up the enzyme. The ions interact with the R-group disrupting weak bonds that hold the tertiary structure of the enzyme by changing the charge. The weak bonds include hydrogen bonds, ionic bonds and disulfide bridges, when these are broken the enzyme becomes denatured as the shape of the active site is changed and unable to form and enzyme-substrate complex.

When denaturing occurs the original structure of the protein is lost and cannot reform. The enzyme becomes ineffective as a catalyst and reduces the rate of reaction as the concentration of enzyme is lowered.

Join now!

Each type on enzyme has its own range of pH in which it functions to its optimum. For example intercellular enzymes have an optimum pH of 7 that is neutral conditions. Strongly acidic or alkaline conditions denature enzymes.

Intracellular enzymes such as digestive enzymes work best in acidic or alkaline conditions. For example the protease enzyme pepsin works best in acidic conditions where it is found in the stomach that has a pH of 2. If the pH was increased the pepsin would denature and would not be able to hydrolyse fats. Trypsin found in the duodenum has an ...

This is a preview of the whole essay