Nature of science:

Developments in scientific research follow improvements in computing—developments in bioinformatics, such as the interrogation of databases, have facilitated research into metabolic pathways. (3.8)

• Metabolic pathways consist of chains and cycles of enzyme-catalysed reactions.
• Enzymes lower the activation energy of the chemical reactions that they catalyse.
• Enzyme inhibitors can be competitive or non-competitive.
• Metabolic pathways can be controlled by end-product inhibition.

Applications and skills:

• Application: End-product inhibition of the pathway that converts threonine to isoleucine.
• Application: Use of databases to identify potential new anti-malarial drugs.
• Skill: Calculating and plotting rates of reaction from raw experimental results.
• Skill: Distinguishing different types of inhibition from graphs at specified substrate concentration.

Guidance:

• Enzyme inhibition should be studied using one specific example for competitive and non-competitive inhibition.

• Many metabolic pathways have been described following a series of carefully controlled and repeated experiments. To what degree can looking at component parts give us knowledge of the whole?

Utilization:

• Many enzyme inhibitors have been used in medicine. For example ethanol has been used to act as a competitive inhibitor for antifreeze poisoning.
• Fomepizole, which is an inhibitor of alcohol dehydrogenase, has also been used for antifreeze poisoning.

• Syllabus and cross-curricular links:
• Biology
• Topic 2.7 DNA replication, transcription and translation
• Chemistry
• Topic 6.1 Collision theory and rates of reaction

Aims:

• Aim 6: Experiments on enzyme inhibition can be performed.
• Aim 7: Computer simulations on enzyme action including metabolic inhibition are available.