Remember these 5 Factors:
1. Temperature
2. pH
3. Inhibitors
4. Concentration
5. Coenzymes or Cofactors
2. pH
3. Inhibitors
4. Concentration
5. Coenzymes or Cofactors
Temperature
- Enzymes are denatured when the temperature rises above their tolerance level.
- At lower temperatures, enzymes are NOT denatured but the reaction happens at a significantly lower rate.
- Denaturation: a process in which proteins lose their unique structure and therefore cannot do their normal job.
- In the graph below, it is evident that enzymes tend to function best in the temperatures of the environment they are typically found in.
The impact of temperature on enzyme activity is both dangerous and useful.
Enzyme denaturation:
- DANGEROUS: if our body temperature rises too high during an infection important enzymes in our brain could denature leading to seizures or death.
- USEFUL: we are able to chew and digest meat more easily after cooking. Cooking meat denatures the enzymes in the meat permanently and makes it easier to digest.
Enzyme denaturation:
- For further information see the red DENATURATION link on page 219 of your textbook (or click here)
- Cooking an egg is a perfect example of irreversible denaturation of proteins due to temperature increases.
Enzymes are affected by pH
Enzymes are denatured when the pH is outside of their tolerance range.
Most enzymes work best around a neutral pH (7)
However, the optimal pH for an enzyme is directly related to the environment in which it is found.
Most enzymes work best around a neutral pH (7)
However, the optimal pH for an enzyme is directly related to the environment in which it is found.
e.g. Digestive enzymes such as pepsin found in the stomach work best in acid conditions
The presence of inhibitors
Substrate and Enzyme Concentrations
- The amount of substrate or enzyme present in a reaction mix can limit the amount of product produced.
- Increasing substrate will result in increased product until all enzymes are working at capacity (saturation point).
- As the amount of enzymes are increases the amount of product increases. The reaction will continue until all of the substrate is depleted.
Cofactors and Coenzymes
Enzymes may need to be activated.
Coenzymes are non-protein organic substances that are required for enzyme activity.
Cofactors are small inorganic substances, such as zinc, magnesium, and iron. Some enzymes require the presence of these cofactors in order to begin the reaction.
Coenzymes are non-protein organic substances that are required for enzyme activity.
- They are relatively small molecules compared to the enzyme.
- E.g. vitamin B1 is a coenzyme that provides the energy to catalyze the breakdown of glucose during respiration.
Cofactors are small inorganic substances, such as zinc, magnesium, and iron. Some enzymes require the presence of these cofactors in order to begin the reaction.
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Question Set 9.2 on page 225
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