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Year 1 Summative 1 > BMS02-1010 Enzyme Kinetics > Flashcards

BMS02-1010 Enzyme Kinetics Flashcards

1
Q

At low substrate concentrations, what can you deduce about reaction rate?

A

They are directly proportional according to 1st order kinetics

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2
Q

Describe zero order kinetics

A

At high substrate concentrations rate of reaction is independent according to 0 order kinetics

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3
Q

What is the michaelis menton reaction model?

A

E + S ES -> E + P
K1
K-1 K2

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4
Q

What are the 3 assumptions of the MM equation?

A

S is far far less then E so the amount of substrate bound at any one time is very small

ES doesn’t change with time, formation is equal to break down

Initial velocities are used as the concentration of the product is small and the backwards reaction of F to S can be ignored

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5
Q

Write the michaelis-menton equation

A

V0= Vmax x (S)

Km + (S)

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6
Q

V0

A

Initial reaction velocity

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7
Q

Vmax

A

Maximum velocity, when all active sites are saturated

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8
Q

Km equation

A

Michaelis constant (K-1 + K2) /K1

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9
Q

What happens when V0=0.5?

A

0.5 (Km + (S)) = Vmax (S)

Km = (S)

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10
Q

Half Vmax =

A

Km

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11
Q

What happens to Km when substrate concentration is increased?

A

Km decreases

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12
Q

What happens to the km equation when K2 is far smaller than the other values?

A

K-1 / K1

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13
Q

What does a low km indicate?

A

High affinity for the substrate

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14
Q

What is the dissociation constant of the ES complex?

A

Kd = K-1/K1

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15
Q

When does km measure the affinity of the enzyme for the substrate?

A

When k2 is far smaller

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16
Q

Why does km only represent affinity when k2 is very small?

A

It’s then a complex function of 3 or more rate constants

17
Q

What does Kcat mean?

A

Number of substrate converted to product in a given amount of time on a single enzyme

18
Q

How do you compare catalytic efficiency?

A

Kcat/Km - the specificity constant

19
Q

What does a high specificity number indicate?

A

A good enzyme

20
Q

What is the lineweaver-burke plot?

A

1/V0 against 1/S

21
Q

What’s the y=mx+c equation?

A

1/V0 = (Km/Vmax) x (1/S) + (1/Vmax)

22
Q

How can you use the graph to find Vmax and Km?

A

X axis = - (1/km)

Y axis = 1/Vmax

23
Q

What else can the graph tell you?

A

If the enzyme is competitive (Km changes) or non-competitive (V max changes)

24
Q

What is used in diastix

A

Glucose oxidase

25
Q

Which enzyme indicates liver damage?

A

Alanine aminotransferase

26
Q

Which enzyme indicates myocardial infarction

A

Heart isoenzyme of lactate dehydrogenase and creatine kinase LDH is better to use 48hrs after the incident as endothelial cells rupture releasing their content

27
Q

Km

A

Affinity of the enzyme

28
Q

How would the graph of an allosteric enzyme differ?

A

Its sigmoid not hyperbolic

29
Q

How is protein fructokinase regulated

A

AMP turns it on

ATP and citrate turn it off

30
Q

How is protein kinase regulated?

A

Fructose -1,6-bisphosphate

31
Q

How is glycogen phosphorylase activated?

A

Phosphorylation

32
Q

How is glycogen synthase regulated?

A

Activity is decreased by phosphorylation

33
Q

Which 3 enzymes can insulin increase the activity of?

A

Glucokinase
Phosphofructokinase
Pyruvate kinase

34
Q

Compare Km and Vmax of heart and muscle LDH

A

If there was lots of lactate in the heart it would kill you so it has a high affinity (low km)

In the muscle there is lots of lactate so it has a low affinity so it leaves the active site quicker (high km)

35
Q

Adenylylation

A

ATP to PPi

36
Q

Uridylylation

A

UTP to PPi

37
Q

Ribosylation

A

NAD

38
Q

Acetylation

A

Transcription

39
Q

How are ACE inhibitors used to treat heart failure?

A

ACE inhibitors block the ACE enzyme so it can’t convert angiotensin 1 to 2, 2 causes vasoconstriction and makes aldosterone which increases Na retention, stopping this reduces cardiac load and water retention so there’s less swelling

Year 1 Summative 1 (56 decks)

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