Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biomolecules of Life > W5 - Enzyme Kinetics > Flashcards

W5 - Enzyme Kinetics Flashcards

1
Q

What is a holoenzyme or an apoenzyme?

A

Holoenzyme - enzyme with co-factor, Apoenzyme - enzyme without co-factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why does changing the activation energy not change the deltaG of the reaction?

A

The start and end energies remain the same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Are all enzymes proteins?

A

No e.g. catalytic RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How do enzymes lower the activation energy?

A

They stabilise the transition state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What enzyme catalyses the conversion between carbon dioxide and carbonic acid?

A

Carbonic anhydrase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Active sites are unique chemical microenvironments and are more likely hydrophobic, what 4 weak interaction occur at the AS?

A

Electrostatic, H-bonding, VdWs and hydrophobic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Does making or breaking a bond release/require energy?

A

Making - releases, Breaking - requires

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Enzymes have no change on delta G and ???

A

Eq constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the equation for rate of reaction?

A

Change in products over change in time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the units for rate?

A

Mol per sec (Ms-1) (Mol/L/s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What 6 things can determine RoR?

A

Conc, catalysts, temp, pressure, pH, number of collisions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the rate equation for A + B –> P?

A

V = k [A][B]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the units of k, the rate constant?

A

M-1 s-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Over time the RoR will go down, why?

A

The amount of substrate decreases as it’s converted to product

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

At equilibrium, what is equal?

A

The rate of the forward and backwards reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is V0?

A

The initial (fastest) rate of reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

At a fixed enzyme conc, what happens to the RoR when the [substrate] increases?

A

RoR increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How to calculate V0?

A

Draw tangent on curve that goes through (0,0)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is on the x and y axis of the Michaelis Menten curve?

A

x - substrate conc, y - reaction velocity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What graph/experiment do you need to do before making the M-M curve?

A

Conc of product against time at multiple different substrate concentration, calculate V0 for each (plotted on M-M curve)

21
Q

What is the Vmax on the M-M curve?

A

Where the graph plateaus

22
Q

What is the M-M formula?

A

V = Vmax ( [S] / ([S] + Km)) where Km is the Michaelis constant

23
Q

What are the 4 things that give evidence for ES complexes?

A

Structural data from crystallography, spectroscopic data, electrophoretic crossing line and saturation effect

24
Q

How does the electrophoretic crossling line experiment give evidence for the ES complex?

A

As the complex forms the molecule gets larger and doesn’t travel as far

25
Q

What are the 2 reversible reactions of enzyme?

A

E+S forms ES, ES forms E + P

26
Q

What are the rate constants for each reaction in enzyme action?

A

E+S –> ES has rate constant of K1 and the reverse rxn has K-1, ES –> E + P has rate constant of K2 and the reverse rxn has K-2

27
Q

Why can we ignore K-2 in the initial rxn?

A

The reverse rxn is minimal

28
Q

What is Vmax?

A

Theoretical maximum rate of reaction

29
Q

What is the equation for Vmax?

A

Vmax = K2[ET] where [ET] is total enzyme conc

30
Q

Describe what the M-M curve tells you?

A

The rate is initially proportional to [S] but it reaches a saturation value (Vmax)

31
Q

At Vmax the ES –> E+P part of enzyme action determines how quickly the enzyme catalyses the reaction, what is the K2 also known as?

A

The Kcat

32
Q

What do you call the enzymes turnover reaction?

A

Catalytic power

33
Q

What 3 things does Km depend on?

A

pH, temp and ionic strength

34
Q

Km is equal to the conc of substrate required for the reaction velocity to be ….

A

Half it’s maximum value

35
Q

When [S] = Km, then V =

A

Vmax/2

36
Q

What does the Km tell you about the M-M curve?

A

The smaller the Km value the steeper the gradient of initial Ror

37
Q

What is the equation for Km?

A

Km = (K-1 + K2) / K1

38
Q

If K2 < K-1, Km is equal to the…

A

Dissociation constant of the ES complex (Kp)

39
Q

Km tells us the affinity of ES complex, If the Km is large/small, what does this tell us about the binding in the ES complex?

A

Large - weak binding, small - strong

40
Q

What is the diffusion limit?

A

The maximum value for K2/Km (the catalytic efficiency constant)

41
Q

What does the value of K2/Km have to be between to be diffusion limited?

A

10^8 and 10^9

42
Q

How to find Km on a graph?

A

Find Vmax, then half Vmax and draw across then down to find Km

43
Q

If glucokinase acts faster but has a lower affinity for substrate and hexokinase acts slower but has higher affinity for substrate what does this tell you?

A

Glucokinase works for storage better at higher glucose levels and hexokinase works in muscles better at lower lower levels

44
Q

What does the Lineweaver -Burk plot, plot?

A

1/V0 against 1/[S]

45
Q

What does the gradient, the y intercept and the x - intercept of the L-B plot tell you?

A

Gradient = Km/Vmax, y - intercept - 1/Vmax, x - intercept - (-1/Km)

46
Q

If 1/Vmax goes up what happens to the Vmax?

A

It decreases

47
Q

If Vmax gets lower and Km remains the same what does it tell us about the activity and affinity of the ES?

A

Activity is lower and affinity is the same

48
Q

What enzymes do not follow the M-M kinetics?

A

Allosteric enzymes (produces sigmoidal graph instead)

Biomolecules of Life (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions