6. Protein Structure Flashcards
What bonds are involved in the primary structure of a protein?
Covalent peptide bonds between amino acids
What bonds are involved in holding together the secondary structure of a protein?
Hydrogen bonds (between backbone, not R groups)
What bonds are present in tertiary and quarternary protein structure?
Covalent - disuphide
Ionic, van der waals, hydrophobic, hydrogen
How do proteins fold?
Ordered process to partially folded intermediates before becoming fully folded
What disease is the result of protein misfolding?
Amyloidosis is the aggregation of abnormal protein structures
How do enzymes increase the rate of a reaction?
Lower the activation energy
What factors will affect reaction velocity?
- Substrate concentration
- Temperature
- PH - extremes can lead to protein denaturation or alter ionisation state of amino residues.
What does the michaelis-menten equation describe?
How velocity of a reaction varies with substrate concentration
Does Km vary with enzyme concentration?
No
What is V0?
Initial reaction velocity
What is Vmax measured in?
Units per time , it is a rate
What is 1 Vmax unit?
The amount of enzyme that converts 1umol of product per min under standard conditions.
What is the relationship between enzyme concentration and rate of a reaction?
The rate of an enzyme catalysed reaction is proportional to the concentration of the enzyme. Double enzyme will double the rate.
What is the activation energy?
The minimum energy a substrate must have to allow the reaction.
What are features of enzymes?
- Highly specific
- unchanged after reaction
- do not alter equilibrium
- increase rate of reaction (both fwd and backwards)
What type of bonds form between substrate and enzyme in the active sites?
Weak, non-covalent bonds such as hydrogen bonds
What shape does the michaelis-menten theory predict that a plot of velocity and [S] will be?
Rectangular hyperbola
When drawing a Vmax line on a graph, what must it not touch?
The line of the graph!!
What is Vmax?
The maximal RATE when all enzyme sites are saturated
What value will not change with enzyme concentration?
Standardised rate will not change with enzyme concentration, rate of reaction will.
What affect will a competitive inhibitor have on Vmax and Km?
Increase Km
No effect on Vmax
What effect will a non-competitive inhibitor have on Vmax and Km?
Decrease Vmax
Km unchanged
On a lineweaver burke plot, what is read from the X axis?
-1/Km
On a line weaver burke plot, what is read from the Y axis?
1/Vmax
