lecture 6 - enzymes Flashcards
What are cofactors?
metal ions
What are coenzymes?
organic molecules
What is the difference between cosubstrates and prosethetic groups?
cosubstrates are transiently associated with the enzyme whereas cofactors are associated with the enzyme
What is a holoenzyme
catalytically active enzyme - cofactor complex
What is a apoenzyme
inactive enzyme (absence of the cofactor)
where can we get cofactors?
The vitamins we eat
what are the units to measure specific enzyme activity?
Umol/min/mg protein
enzyme unit
amount which gives 1 Umol product/ min
Katal (SI unit)
Amount which gives 1Mol/sec
What is the Michaelis - Menton equation?
Vmax(S) / Km +(s)
What is an assumption of the steady state diagram?
K-1 is greater than k2. Therefore there is an equilibrium between (ES) and (E) + (S)
What is Km?
The substrate concentration at which the reaction rate is half of the maximal value
Unit for Km?
M
What is Vmax?
Reaction rate when the enzyme is fully saturated by the substrate
What is the units for Vmax?
Umol/min
What is Kcat?
Equal to K2. It measures. the number of substrate molecules “ turned over” by enzyme per second
what is the unit for Kcat?
1/second
What can be inferred when an enzyme has a small Km?
Achieves maximal catalytic efficiency at low substrate concentrations
What is Kcat equal to?
K2
What does K2 measure?
number of molecules ‘turned over’
What is Ks
The dissociation constant
What is the formula for KS?
k-1 divided by K1
This equals; Enzyme times substrate divided by the enzyme substrate complex.
What does Vo represent on a Michaelis Menton equation?
The initial rate
What can we assume due to the steady state assumption?
The rate of change of The enzyme substrate complex = 0
