3.1.4 Proteins

Question 1

Describe an enzymes structure.

Answer 1

• An enzyme is a type of protein.

• Proteins have a primary structure that is formed by a sequence of amino acids that are joined by peptide bonds in a condensation reaction.

• The primary structure folds into a secondary structure of either alpha helix or beta pleated sheets and these are held together by hydrogen bonds.

• The secondary structure further folds into a tertiary 3D structure that is held together by hydrogen bonds, ionic bonds and disulphide bridges.

• Folding of the amino acid chain into the tertiary structure dictates the shape of the active site, which is complementary to the substrate.

Question 2

How does a competitive inhibitor work?

Answer 2

• Inhibitor binds to active site.

• Which prevents the substrate from binding to the active site.

• Meaning there are fewer enzyme substrate complexes being formed.

Question 3

How does a non-competitive inhibitor work?

Answer 3

• Inhibitor binds to allosteric site.

• Which changes the shape of the tertiary structure and therefore active site.

• Meaning the substrate is no longer complementary to the active site.

• So fewer enzyme substrate complexes form.