Enzymes Flashcards
What are enzymes?
Biological catalysts that speed up metabolic reactions, they do not change during the reaction and can be reused.
What is activation energy?
Energy needed to overcome the energy barrier.
What does the lock and key model propose?
The enzyme active site is an exact match for the shape of the substrate (they are complimentary in shape).
What does the induced fit model propose?
The active site can mould itself around the substrate forming a precise fit.
What are cofactors?
Non-protein substances that enzymes require in order to function.
What are prosthetic groups?
Another type of cofactor.
What are coenzymes?
Non-protein, organic molecules needed for enzyme action, they are not permanently attached
What are some factors that affect enzyme activity?
- Substrate and enzyme concentration
- Temperature
- pH
What is the optimum temperature to increase enzyme activity?
In mammals the optimum temperature is 40 degrees.
What in enzyme inhibition?
Substances that interfere with enzyme activity. They reduce enzyme activity by either directly or indirectly affecting the functioning of the active site.
What is competitive inhibition?
When the inhibitor substance competes with the usual substrate for the active site.
What is non-competitive inhibition?
When the inhibitor attaches itself to a part of the enzyme other than the active site. This leads to the changing of the active site’s shape.
What type of enzyme can be used as a diagnostic tool to confirm that a particular disease is present in the body?
Elastase.
How does elastase work?
Released by white blood cells as a consequence of lung infection. Elastase breaks down bacterial pathogens and is part of the immune response.
What do enzymes need to be in the role of therapeutic drugs?
Specific so they will only target an enzyme involved in disease progression. And able to work well at low doses.
What are immobilised enzymes used for?
Vitally important in regulating metabolism in living organisms.
What are the four principal methods of immobilisation?
- Adsorption
- Entrapment
- Encapsulation
- Cross-linkage
What is Adsorption?
The enzymes are attached by weak forces to an inert substance such as glass or matrix.
What is Entrapment?
The enzymes are trapped within polymers such as alginate beads or microspheres.
What is Encapsulation?
The enzymes are trapped within a selectively permeable membrane such as nylon.
What is Cross-linkage?
Enzymes are bonded covalently to a matrix such as cellulose as a consequence of chemical reactions.
What are the advantages of enzyme immobilisation?
- They remain stable and are more effective over a wider range of temperatures than enzymes that are not immobilised.
- More resistant to changes in pH
- Enzymes can be retained and reused.
- There is no contamination of the end product, avoiding possible allergic reactions in consumers.
How are diagnostic reagent stripes used as biosensors?
They are very specific and can be used to identify individual molecules, and they are quantitative.
Why are enzyme inhibitors used in diagnostic reagent strips?
The inhibitors are attached to the diagnostic strips and as the patient sample is added, the enzyme being monitored is captured by its active site on the diagnostic strip to give a positive read out.
