Enzymes - Kinetics And Inhibition

Question 1

Increasing the rate of a reaction

Answer 1

Temperature - increase the number of molecules with sufficient activation energy
Concentration - increase the chance of molecular collisions
Enzymes - lower the activation energy and facilitate the formation of ten transition state

Question 2

Enzymes

Answer 2

Features:
- highly specific 
- remain unchanged after the reaction
- increases the reaction rate 
- are proteins (may require associated cofactors) 
Clinical importance:
- inheritable genetic disorders
- overactive enzymes can cause disease 
- measurement of enzyme activity for diagnosis 
- inhibition of enzymes by drugs

Question 3

Active site

Answer 3

The place where the chemical reaction occurs
Most of the enzyme is acts as a scaffold to create the active site
Are clefts or crevices
Lock and Key hypothesis - have a complimentary shape to substrate
Induced fit hypothesis - binding of substrate induces changes in the conformation of the active site
Substrates are bound to enzymes by multiple weak bonds (non-covalent)

Question 4

The Michaelis-Menten model

Answer 4

Vo = Vmax[S]/(Km + [S])

Where Vo is the initial velocity and Km is the Michaelis constant

Question 5

Vmax

Answer 5

The maximal rate when all enzyme active sites are saturated with substrate (the Y-axis value)
Affected by non-competitive inhibition - binds at a site other than the active site - decreases the number of enzymes available for the substrate - lowers Km

Question 6

Km

Answer 6

Substrate concentration that gives half the maximal velocity (the X-axis value)
Low Km = high affinity for the substrate
Affected by competitive inhibition - the inhibitor competes with the substrate for the active site Km increases

Question 7

Chemical reactions

Answer 7

Activation energy = minimum energy substrate must have to allow the reaction
Transition energy = high energy intermediate that lies between the substrate and the product