Enzymes Flashcards
What is a cofactor?
A non-protein component needed for activity, usually metal ions
What is a co-enzyme?
A complex organic molecule, usually produced from a vitamin FAD NAD+
Why isn’t a spontaneous reaction instantaneous?
Because of the activation energy barrier
What position are the molecules in when the activation energy has been used?
chemical groups correctly positioned for reaction
What is the transition state?
The moment that chemical bonds are formed and broken The reaction from this point could then go to products or reactants
How do enzymes reduce activation energy?
Entropy reduction Desolvation Induced fit
How does entropy reduction reduce activation energy?
Molecules react by bumping into each other, enzymes orientate the substrates improving the chance of a successful collision and a resulting reaction
How does desolvation decrease the activation energy?
H bonds with the substrate and the solution are replaced by the weak bonds between the substrate and the enzyme.
How does induced fit decrease activation energy?
Conformational changes occur in the protein structure when the substrate binds reducing orientation energy
What is Km?
It is the substrate concentration when the reaction velocity is exactly half of the max velocity
On a lineweaver burke plot what does the y intercept represent?
1/VMax
On a lineweaver burke plot what does the X intercept represent?
1/Km
What does Km measure?
The ration of rate constant for breakdown of ES to E+S compared to the rate constant for formation of ES from E+S It gives you a clue to the affinity of the enzyme with it’s substrate
Which enzyme activity fluctuates directly with blood glucose intake?
Glucokinase Catalyses Glucose + ATP to glucose - 6 - phosphate
How are enzymes separated?
Gel electrophoresis
How does temperature affect the function of an enzyme?
Increase temperature will increase molecule collisions and it will increases the internal energy of molecules
Eventually denautres the enzyme
How does pH alter the function of an enzyme?
pH changes the charge of an amino acid, can stop the active site functioning if the amino acids in the active sites change charge.
Extreme pH will denature the enzyme
pH will affect the substrates
What effect does a competetive inhibitor have on the Vmax and Km?
Same Vmax
Km increases (since affinity active site has for the enzyme substrate complex decreases)
What effect do non-competitive inhibitors have on the Vmax and the Km values?
V max will decrease - inhibition remains the same regrdless of the change in substrate concentration
Km remains the same as the substrate is still able to bind to the active site
What is feedback inhibition?
When there is a build up of an end product in a pathway or a key junction in a pathway that ultimately slows down the entire pathway
What does a high Vmax but low Km indicate?
Fast enzyme but bad fit
What does a low Vmax and high Km indicate?
Slow enzyme but good fit
Give 3 reasons to measure enzymes in a clinical setting
- Detection of suspected disease
- Measure damage caused by disease
- Diagnose enzyme disorder (Genetic condition)
- Measure of medication effectiveness
- Locate area of disease
- Organ functioning test
- Detect vitamin deficiencies
- Detection of specific step in pathology
What Natural factors affect enzyme levels?
- age
- gender
- pregnancy
- race
- time of day
- genetics
- drugs
- disease process, progress and treatment e.g. Surgery
- Immune disorders – anaphylaxis, autoimmune disease etc
What Unnatural factors affect enzyme levels?
- Hypoxia
- Cellular damage
- Physical damage
- Microbiological agents
- Nutritional disorders
What 2 problems arise when measuring enzyme levels in a lab?
- Not specific (could indicate many problems in many different areas
- Need optimised environment
