Factors Affecting Enzyme Action Flashcards
(21 cards)
What factors affect the rate of enzyme controlled reactions?
- Temperature
- pH levels
- Substrate concentration
- Enzyme concentration
- Inhibitors (competitive and non - competitive)
What happens to enzymes when the temperature is too low during enzyme controlled reactions?
If temperature is too low, there will be insufficient kinetic energy levels fo successful collisions between the enzyme and substrate
What happens to enzymes when the temperature is too high during enzyme controlled reactions?
If temperatures are too high enzymes will denature. This makes the structure of the active site change, leading to the active site shape changing too. This prevents substrates from binding to active site and forming enzyme - substrate complexes
Why do enzymes denature at higher temperatures?
The bonds that hold the amino acids in their fixed tertiary structure in the active site are broken as the enzyme molecules gain even more kinetic energy
What affect do pH levels have on enzymes?
If pH levels are too low there will be too many -0H ions. If pH levels are too high there will be too many H+ ions. The increased levels in these ions will interfere with the charges in the amino acids in the active site
Why are enzymes affected by different pH levels?
Enzymes that have pH levels that are too high or too low will have either many H+ ions or OH- ions. This will result in bonds holding the tertiary structure in place to break, therefore changing the active site’s shape
Do all enzymes have the same optimal pH level?
Enzymes have different optimal pH levels. For example, amylase has a more alkaline level and proteases have a more acidic level
What affect does a low substrate concentration have on enzyme controlled reactions?
An insufficient substrate concentration, leads to slower rates of reactions. This is because of the fewer collisions occurring between the enzyme and substrate
When you reach a higher rate of reaction, whilst adding substrate concentration, there is a plateau.
What becomes the limiting factor in the reaction?
Explain why
The limiting factor becomes the enzyme concentration. This is because when you add more and more amounts of substrate the enzyme active sites become saturated. The addition of more enzymes has been neglected, so without more enzymes to form enzyme - substrate complexes
What affect does insufficient enzyme concentration have on the rate of enzyme controlled reactions?
Having insufficient enzymes will cause the enzyme active sites to become saturated with the substrate concentration and unable to work faster, leading to a slower rate of reaction.
When you reach a higher rate of reaction, whilst adding enzyme concentration, there is plateau
What becomes the limiting factor in the reaction, and explain why?
The limiting factor now becomes the substrate concentration. This is because there will be too many active sites without any substrates to form enzyme substrate complexes due to insufficient substrates
What would the graph look like if there were equal parts of enzyme and substrate concentration?
If there was an equal supply of both enzyme and substrate concentration there would be a directionally proportional line on the graph. Showing a positive correlation indefinitely
What are inhibitors?
Inhibitors are molecules which bind to the active site of an enzyme, preventing the enzyme from functioning
How many types of inhibitors are there and what are they called?
There are two types: competitive inhibitors and non -competitive inhibitors
What are competitive inhibitors?
Competitive inhibitors are molecules that are similar to the shape of the substrate, complementary in shape to the active site. This makes them capable of binding and forming an enzyme inhibitor complex
What effect do competitive inhibitors have on enzyme controlled reactions?
Competitive inhibitors prevent the substrate from binding and enzyme controlled reactions occurring. As a result enzyme substrate complexes will not form
How can you prevent competitive inhibitors from inhibiting enzymes?
By adding more substrate, the substrates will out compete the competitive inhibitor, knocking them out the active site. This will lead to a normal rate of reaction
What are non - competitive inhibitors?
Non - competitive inhibitors are molecules that bind to the enzyme away from the active site, known as the allosteric site
What is the site called where the non - competitive inhibitors bind to the enzyme?
The allosteric site
What affect do non - competitive inhibitors have on enzyme controlled reactions?
Non - competitive inhibitors slightly change the structure and lead to the active site changing shape. The change in active site’s shapes results in the substrate being unable to bind, no matter how much substrate is added
How do you identify the different reactions based on the presence or the lack of inhibitors?
If there are no inhibitors the rate of reaction will be at the highest
If there is a competitive inhibitor present, the rate of reaction will be in the middle, the rate of reaction will be lower than no inhibitors, but will increase toward the end due to increased substrate concentration
