proteins : enzymes
intro to enzymes
What is an enzyme?
A protein with a specific tertiary structure
A biological catalyst
What do enzymes do?
Enzymes lower the activation energy of the reactions they catalyse to speed up the
reaction
Where do enzymes catalyse reactions?
They catalyse a wide range of intercellular and extracellular reactions
the induced fit model
1. The enzyme’s active site is not completely complementary to the substrate
2. As the substrate binds to the active site, the active site changes shape to become
complementary to the substrate
3. An enzyme-substrate complex forms
4. This stresses the bonds in the substrate, which leads to a reaction and the products being
released
5. After the products are released, the active site changes back to its original shape
the specificity of enzymes
What do enzymes have that make them specific?
A specific shaped tertiary structure and active site
What determines the tertiary structure?
proteins : enzymes 1
, The primary structure / sequence of amino acids
What can the active site become complementary / bind to?
A specific substrate
factors that affect the rate of enzyme activity
enzyme concentration
Why does increasing enzyme
concentration increase the rate of
reaction?
Enzyme concentration is the
limiting factor
More enzymes means more active
sites available
→ more successful enzyme-
substrate collisions
→ more enzyme-substrate
complexes formed per unit of time
When the rate of reaction plateaus,
this means the substrate
concentration is now the limiting
factor
substrate concentration
Why does increasing substrate
concentration increase the rate of
reaction?
Substrate concentration is the
limiting factor
More substrates means more
occupied active sites
proteins : enzymes 2
intro to enzymes
What is an enzyme?
A protein with a specific tertiary structure
A biological catalyst
What do enzymes do?
Enzymes lower the activation energy of the reactions they catalyse to speed up the
reaction
Where do enzymes catalyse reactions?
They catalyse a wide range of intercellular and extracellular reactions
the induced fit model
1. The enzyme’s active site is not completely complementary to the substrate
2. As the substrate binds to the active site, the active site changes shape to become
complementary to the substrate
3. An enzyme-substrate complex forms
4. This stresses the bonds in the substrate, which leads to a reaction and the products being
released
5. After the products are released, the active site changes back to its original shape
the specificity of enzymes
What do enzymes have that make them specific?
A specific shaped tertiary structure and active site
What determines the tertiary structure?
proteins : enzymes 1
, The primary structure / sequence of amino acids
What can the active site become complementary / bind to?
A specific substrate
factors that affect the rate of enzyme activity
enzyme concentration
Why does increasing enzyme
concentration increase the rate of
reaction?
Enzyme concentration is the
limiting factor
More enzymes means more active
sites available
→ more successful enzyme-
substrate collisions
→ more enzyme-substrate
complexes formed per unit of time
When the rate of reaction plateaus,
this means the substrate
concentration is now the limiting
factor
substrate concentration
Why does increasing substrate
concentration increase the rate of
reaction?
Substrate concentration is the
limiting factor
More substrates means more
occupied active sites
proteins : enzymes 2
