Enzymes: Nature and Mechanism of Action
Introduction to enzymes as biocatalysts, their characteristics, and theories explaining their catalytic action (lock and key, induced fit).
What is Enzymes: Nature and Mechanism of Action?
A biological catalyst, typically a protein, that accelerates the rate of a specific biochemical reaction without being consumed in the process.
Key points
- Define enzymes and their role as biocatalysts.
- Explain the concept of enzyme specificity.
- Describe the structure and function of the enzyme's active site.
- Differentiate between the Lock and Key and Induced Fit models of enzyme action.
Common exam trap
Confusing enzymes with general chemical catalysts.
Definitions
- Term
Enzyme
- Meaning
A biological catalyst, typically a protein, that accelerates the rate of a specific biochemical reaction without being consumed in the process.
- Term
Biocatalyst
- Meaning
A catalyst that is biological in origin, usually an enzyme.
- Term
Activation Energy
- Meaning
The minimum amount of energy required to initiate a chemical reaction.
- Term
Active Site
- Meaning
The specific region on an enzyme molecule where the substrate binds and catalysis occurs.
- Term
Substrate
- Meaning
The molecule upon which an enzyme acts.
- Term
Lock and Key Hypothesis
- Meaning
A model of enzyme action where the active site of the enzyme has a rigid shape that precisely fits the shape of the substrate.
- Term
Induced Fit Model
- Meaning
A model of enzyme action where the active site of the enzyme is flexible and changes its shape to accommodate the substrate upon binding.
- Term
Denaturation
- Meaning
The process by which the three-dimensional structure of a protein (like an enzyme) is altered, leading to loss of its biological function.
Learning objectives
Define enzymes and their role as biocatalysts.
Explain the concept of enzyme specificity.
Describe the structure and function of the enzyme's active site.
Differentiate between the Lock and Key and Induced Fit models of enzyme action.
Identify factors affecting enzyme activity.
Prerequisites
Basic understanding of protein structure (primary, secondary, tertiary, quaternary).
Knowledge of chemical reactions and activation energy.
Familiarity with concepts of catalysis.
Understanding of molecular interactions (e.g., binding).
Common mistakes
Confusing enzymes with general chemical catalysts.
Assuming enzymes can catalyze any reaction.
Not understanding the role of the active site and its specificity.
Forgetting that enzymes are proteins and can be denatured.
Misinterpreting the Lock and Key and Induced Fit models as identical.
Keywords
Enzyme
Biocatalyst
Protein
Catalysis
Activation Energy
Active Site
Substrate
Specificity
Lock and Key
Induced Fit
Denaturation
Enzyme Kinetics
Regulation
Inhibitor
Activator
Practice preview
A competitive inhibitor binds to the enzyme:…
hard
The 'lock and key' hypothesis for enzyme action suggests that:…
easy
According to the induced fit model of enzyme action, the enzyme's active site:…
medium