Factors affecting enzyme action Flashcards
What factors affect enzyme action?
Temperature, pH, concentration of substrate and enzymes and presence of inhibitors.
What happens when you increase the temperature?
It increases the kinetic energy of the enzyme and substrate molecules allows and to collide with enough energy more often increasing the rate of reaction. The rate doubles every 10°C to around 40°C for most enzymes.
What happens after 40°C for enzymes?
After 40° the molecules have even more kinetic energy however the rate of the reaction decreases due to an increase in vibrations breaking the weak hydrogen bonds found at the active site which changes the tertiary structure. The altered active site no longer fits the substrate so the enzymes have now denatured which is a permanent change in the structure.
What happens at low temperatures?
At low temperatures the enzyme is inactivated as the molecules have low amounts of kinetic energy. The shape is still unchanged so the enzyme can work again if the temperature is increased.
How does PH affect the rate of enzyme action?
Small changes in pH around the optimum cause more reversible changes in the structure and reduce the enzymes activity but extreme changes causes the enzymes to denature.
What happens at low pH and high pH levels?
At low pH levels excess H+ ions are attracted to the negative charges and neutralise them. At high pH’s access OH- ions neutralise the positive charges which disrupts the hydrogen and ionic bonds maintaining active site.
How does substrate concentration affect the rate of reaction?
If the enzyme concentration is constant the rate of reaction increases as the substrate concentration increases as more active sites are filled. The substrate concentration controls the rate of reaction and is the limiting factor in. Once a concentration has reached the maximum, all active sites are filled and the rate of reaction has reached maximum. When all active sites are filled the enzyme is saturated.
What happened at low concentration of substrate molecules?
There are only a few substrate molecules that the enzyme can collide with meaning the active site is not working at its full capacity.
What happens when the rate of reaction has plateaued?
The enzyme concentration is now the limiting factor meaning that the substrate concentration is no longer controlling the rate of reaction.
What happens as the enzyme concentration increases?
More active sites are available and therefore the rate rate increases. Once the line plateau the limiting factor is now the substrate concentration.
