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
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
