Lecture 5- Enzymes Flashcards
What problem would the body have without enzymes?
Many reactions would require temperatures far greater than 37 degrees to happen.
What read the important features of enzymes?
Proteins Some require cofactors Don’t affect equilibrium Speed up reactions Highly specific Unchanged after reaction
Why are we interested in enzymes?
Inheritable genetic disorders
Drugs can target them
Used in diagnosis
Overactive enzymes can cause disease
What is the lock and key and induced fit hypothesis?
Lock and key- enzymes have a complimentary shape to the substrate
Induced fit- binding of substrate can induce changes in active site conformation
What type of bonds are formed between substrate and enzyme?
All types of non-covalent bonds
Can’t be too tight
Hydrogen bonds common
What is V0
Initial rate of reaction- only time substrate concentration is known
How does enzymatic reaction speed change with time?
Fast initially and then slows as less substrate available
Where do you draw maximal velocity line on graph
Just above the max of the graph
What does the Michael is mention equation propose?
That the complex between enzyme and substrate is a necessary intermediate in catalysis.
What is vmax?
Maximal reaction rate when all enzymes are saturated with substrate
What does the km value tell you?
Gives a measure of the affinity of an enzyme for its substrate
Why is varying km values of enzymes important?
Some enzymes you want active at low substrate concentrations whereas others you only want activated when substrate levels are high. Eg glucokinase after feeding
If enzyme concentration is doubled will reaction rate double?
Yes as long as there is excess substrate present. The rate of an enzyme catalysed reaction is proportional to the concentration of the enzyme.
What is unit in terms of enzymes
A unit is the amount of enzyme that converts 1 micro mole of product per minute under standard conditions.
What is a line weaver burk plot?
Michaelis mention equation rearranged to give linear plot and uses reciprocals. Allows for easy estimation of vmax and km.
