B M 5 : Factors Affextingn Enzyme Activity Flashcards
What two things affect an enzymes activity?
Temperature and pH
What happens to the rate of an enzyme- controlled reaction when temperature increases
It increases
What happens to the enzyme molecules as temperature increases?
They vibrate more
What happens if temperature goes above a certain level?
Vibration breaks some of the bonds that hold the enzyme in shape
- so active site changes shape and enzyme + substrate no longer fit together
What does it mean when an enzyme and substrate no longer fit?
Enzyme is denatured
-no longer functions as a catalyst
What’s the optimum temperature?
The temperature the enzyme denatures after
For human enzymes what’s the optimum temp?
37
For biological washing powder enzymes what’s the optimum temperature?
60
What do all enzymes have?
An optimum pH value
What do most human enzymes work best at for pH
7
What pH does pepsin work best at?
Acidic pH 2
- as fond in stomach
Above or below the optimum pH how can it affect enzymes?
The H+ and H- ions found in acids and alkalis can mess up Ionic and hydrogen bonds that hold enzymes tertiary structure in place
- changes enzymes active site shape so enzyme is denatured
What affect enzyme rate of reaction?
- Enzyme concentration
- Substrate concentration (up to a point)
How enzyme concentration affects rate of reaction?
-more enzyme molecules there is in solution, the more likely a substrate molecule will collide with one and form an enzyme substrate complex
What happens if the amount of substrate is limited in an increase in enzyme concentration?
- enzyme has no further affect
How does substrate concentration affect rate of reaction?
- more substrate molecules means a collision between substrate + enzyme is more likely and so more active sites used
As substrate concentration decreases what happens to the rate of reaction?
It decreases if no further substrate is added
What can prevent enzyme activity
Enzyme inhibitors
What are enzymes inhibitors?
Molecule that binds to enzyme that they inhibit
What two things can inhibitors be?
-competitive
OR
-non-competitive
Shape of competitive inhibitors?
Similar shape to the substrate molecule
What do competitive inhibitors do
They block the active site
How much the competitive enzyme inhibits the enzyme depends on what?
The relative concentrations of the inhibitor and substrate
- if high concentration of inhibitor will take up nearly all active site and hardly any substrate gets to enzyme
What if there’s a high substrate concentration?
The substrates chances of getting an active site before inhibitor increases
-so increase concentration of substrate increase rate of reaction
What do non-competitive inhibitors do?
Bind to the enzyme away from its active site
-causes active site to change shape
Does increases the concentration of substrate affect non competitive inhibitors ?
No - rate of reaction won’t be affected as enzyme inhibitor doesn’t compete
