Biochemistry E2 Flashcards
What is the fractional saturation of binding?
Y= [S] ÷ (KD + [S])
The concentration of bound ligand divided by the total amount of protein/enzyme
What is KD
The dissociation constant or the [S] at half the saturation
What is KD related to when the protein is enzymatic/catalytic?
KD=KM
In a Sctchard plot graph, when n=1,
Slope
x-intercept
y-intercept
Slope: -1/KD
x-intercept = [E]T
y-intercept = 1/KD
In a Sctchard plot graph, when n>1,
Slope
x-intercept
y-intercept
Slope: -1/KD
x-intercept = n
y-intercept = n/KD
What is the Hill Equation?
Log(ø ÷ (1-ø)) = Log (1/KD) + nLog[S]
What type of graphs are Hill Plots usually?
Sigmoidal
What does the slope of the Hill plot tell us?
Slope= n
n>1 = Positive cooperativity
0
What is the y-intercept of the Hill plot?
log(1/KD) = log(1/Km)
Michaelis-Menten Kinetics follow what order of enzymes?
First Order Enzymes
What does the graph of Zero-order kinetics look like?
If [S] vs time is linear, the reaction is 0-order
v=k
What does the graph of First-order kinetics look like?
If ln[S] vs time is linear, the reaction is 1st order
v=k[S]
What does the graph of Second-order kinetics look like?
If 1/[S] vs time is linear, the reaction is 2nd order
v=k[S][S] or v=k[S1][S2]
What is the initial reaction rate equation?
V0 = Vmax • [S] ÷ ([S] + Ks)
What are the three assumptions for Michaelis-Menten Kinetics?
- Binding of the substrate to the enzyme is at equilibrium
(Ks = K-1/K1) - Since we are measuring initial rate, not enough product is present for the reverse reaction to occur
(Secon step is irreversible) - Stead State Assumption
What is the steady state assumption?
- When [S] is very large, ∆[S] = 0
- Formation of E•S complex occurs at the same rate that its loss either by dissociation or by product formation
Define Km
Michaelis Menten constant
When [S] where half the active sites are full
OR
When [S] where the reaction is half maximal
What is the equation for the Michaelis Menten Kinetics?
V0= Vmax • [S] ÷ ([S]+Km)
Define Vmax
How fast the reaction can take place
Vmax = Kcat[E]
Kcat is the same as
K2
Movement from E•S complex to E•P complex
(Changing Substrate to Product)
What happens when [S]<
V0 = (vmax÷Km) * [S]
Less than half the binding sites are occupied
What happens when [S]=Km
V0 = Vmax/2
Half the binding sites are occupied
What happens when [S]»Km
V0 = Vmax
All the binding sites are occupied
What is the specificity constant?
Kcat ÷ Km = (Kcat ÷ (K-1 +Kcat)) •K1
Used to determine catalytic efficiency
Measures what happens when to E•S complex
A good enzyme vs a poor enzyme
Good enzymes: Kcat»K-1
(More production of product)
Poor Enzymes: Kcat<
Lineweaver-burk plots are used for
reversible inhibitors
What is vmax and Km with a competitive inhibitor?
Vmax is constant and Km is variable
Inhibitor binds at the enzyme
What is vmax and Km with a Noncompetitive inhibitor?
Vmax is variable and Km is constant
Inhibitor binds at Enzyme or E•S complex
What is vmax and Km with an uncompetitive inhibitor?
Vmax is variable and Km is variable
Binds at E•S complex
Constitutional Isomers
Changes orders of atoms
Also called Tautomers
Stereoisomers have the
same connectivity, but different spatial organization
Configurational Isomers are
Stereoisomers that have chiral carbons
Enantiomers are
mirror images at ALL CHIRAL centers
Diastereomers have
multiple chiral centers, but not all chiral centers are mirror images
The anomeric carbon decides
Whether it is an alpha or beta carbohydrate in the ring form
Beta is up
Alpha is down
When converting from fischer to hawthorn projections, What goes up and what goes down?
Right side is down
Left side is up
Anomers vis epimers
Anomers differ at the anomeric carbon
Epimers differ at locations other than the anomeric carbon
