Enzymes Flashcards
What is an enzyme
A globular protein with a specific shape. It is a biological catalyst
What is a catalyst
Something that speeds up the rate of reaction
Why are enzymes useful in small amounts
Because they don’t run out so can be re used
What is an enzyme substrate complex
When the substrate fits into the active site of the enzyme
How is the substrate held within the active site
By temporary bonds between amino acids in the active site and on the substrate
What is the induced fit model
Before enzyme and substrate interact, the active site isn’t complementary to substrate. Proximity of a substrate leads or change in enzyme that forms functional active site, via induced fit so ESC is formed. As it changes shape, the enzyme puts a strain on the substrate which distorts bonds and lowers activation energy needed to break bonds and products are formed, the enzyme is unchanged
Why is the lock and key model disproved
Because the enzyme is not a rigid structure, the active site is altered by the substrate
How do enzymes work
By lowering the activation energy level so reactions can take place at a lower temperature
How does the function of an enzyme relate to its tertiary structure
Tertiary structure of active site allows complimentary substrates to bind, forming enzyme substrate complexes
Describe the specificity of an enzyme
Enzymes are specific as the have differently shaped active sites which are only complimentary to it’s substrate
What is the effect of enzyme concentration on rate of reaction
Increasing enzyme concentration will speed up the rate of reaction as long as there’s substrate. Once substrate is bound, the reaction will no longer speed up
What’s the effect of substrate concentration on rate
Initially, an increase leads to an increased rate (more substrates colliding with enzymes so more product) it then levels off (enzymes saturated)
What is a competitive inhibitor
Have similar shape to substrate so it occupies the active site
Effect of competitive inhibitor on rate of reaction
They reduce the rate as they prevent E-SCs because they fit in the active site but remain unreacted. This is temporary as it eventually leaves the enzyme
How does a non competitive inhibitor work
They prevent products from being formed as they bind to a site OTHER than the active site (allosteric) which distorts the tertiary structure, so it can’t catalyse a reaction
