Skip to content
Clear highlightsClear Highlight Report a problem

Effect of pH on Enzyme Action

The tertiary structure of the active site of the enzyme is determined by hydrogen and ionic bonds between -NH2 and -COOH groups and bonding and interactions between the R-groups.Each enzyme has an optimum pH.Since the pH is a measure of the hydrogen ion concentration, changes to the H+ concentration may alter the shape of the active site by:
  • altering the charges on the amino acids that make up the active site
  • breaking the hydrogen and ionic bonds that maintain the enzymes tertiary (3D) structure and causing the shape of the active site to change
Small changes in pH will reduce the enzymes activity.Large changes in pH will denature the enzyme.

Read the text

Read the text and highlight anything you think is important. When you go on, the text is hidden and you answer from memory.

Next

Specification: AQA Biology (7401), AS-level, 3.1.4.2 Many proteins are enzymes. Topic: Enzymes.

Key terms in this lesson

ionic bond
A strong bond formed by the electrostatic attraction between oppositely charged ions.
tertiary structure
The further coiling and folding of a polypeptide into a specific three-dimensional shape, held by ionic bonds, hydrogen bonds and disulfide bridges between R-groups.
active site
The region of an enzyme, formed by the tertiary structure, with a shape complementary to its substrate, where the substrate binds.
denaturation
A permanent change to the tertiary or quaternary structure of a protein, caused by heat or pH extremes, that alters the shape of the active site so it is no longer complementary to its substrate.

More in Enzymes

All 17 lessons in Enzymes · All AQA AS-level Biology topics