Enzyme 2

Question 1

What are the four ways you can control enzyme activity?

Answer 1

Alter temperature
Alter chemical conditions eg pH
increase or decrease transcription or breakdown
Direct regulation of the enzyme molecule

Question 2

What is cooperativity?

Answer 2

substrate-binding to one site increase affinity at another

Question 3

An allosteric activator shifts the V [S} graph to the ….

Answer 3

shifts to the left

in the classic enzyme graph shape

Question 4

An allosteric inhibitor shifts the V [S] graph to the ….

What is the new shape of the graph?

Answer 4

shifts to the right

new shape is sigmodal

Question 5

What is Vmax for an allosteric inhibitor and activator compare to an average enzyme

Answer 5

Allosteric inhibitor has a lower Vmax

Allosteric activator has a higher Vmax

Question 6

What is the effect of temp on V?

Draw a graph to explain this.

Answer 6

There is a slow increasing gradient.

There is an optimum temperature and after this the graph drops off fast.

Question 7

What is the effect of pH on V?

Draw a graph to explain this.

Answer 7

pH graph looks like a mountain and it gets shifted to the left or to the right.

Question 8

What is the effect of [Enzyme] on V

Explain via a graph

Answer 8

Positive gradient line through the origin

Remember Vmax= kcat x [E]

Question 9

What are the two types of covalent enzyme regulation?

Answer 9

1) cleavage of peptide chain in zymogen

2) phosphorylation

Question 10

Is the cleavage of peptide chain in zymogen reversible?

Answer 10

No

Question 11

Is phosphorylation reversible?

Answer 11

yes

Question 12

What is two non covalent method of enzyme regulation?

Answer 12

Reversible binding of molecules to specific sites

Increase or decease activity

Question 13

State the equation to find the inhibition factor

Answer 13

If= 1+ [I] / Ki

Question 14

Irreversible inhibitors include suicide substrates.

Name an example

Answer 14

aspirin

penicillin

Question 15

Competitive inhibitors block what?

Answer 15

the binding between E + S and ES

Question 16

Non-Competitive inhibitors block what?

Answer 16

the catalysis between ES and E + P

Question 17

What do these inhibitors bind to?

Competitive
Uncompetitive
Non-Competitive

Answer 17

Competitive- Binds to only free E
Uncompetitive- Binds to only ES
Non-Competitive- Binds the either

Question 18

What is the equation for V including IF for competitive inhibitors?

Answer 18

V= Vmax x[S] / (Km xIf) + [S]

Question 19

What is the equation for V including IF for non competitive inhibitors?

Answer 19

V= (Vmax/If) x [S] / Km + [S]

Question 20

What is the equation for V including IF for uncompetitive inhibitors?

Answer 20

V= Vmax x[S] / Km +([S] xIf)

Question 21

X= 1/[S] y= 1/v

What does the line look like for a uncompetitive inhibitor?

Answer 21

Straight line to the left of the original line / /
V max seems to be smaller
Km seems to be smaller

Question 22

X= 1/[S] y= 1/v

What does the line look like for a competitive inhibitor?

Answer 22

Inhibitor line crosses the other at the y intercept

Vmax is the same
Km seems to be larger

Question 23

X= 1/[S] y= 1/v

What does the line look like for a noncompetitive inhibitor?

Answer 23

Inhibitor line crosses the other on the x axis

V max is smaller
Km is the same

Question 24

What do mixed inhibitors bind to ?

Do the lines on the 1/v 1/[S] cross?

Answer 24

Binds to either but different affinity to E and ES

Lines cross but not on axis

Question 25

Name an example of the use of competitive and non competitive inhibitors?

Answer 25

Competitive= Viagra statins

Non competitive= Turmeric

Question 26

What are the 2 types of multiple substrate/product reactions?

Answer 26

Sequential Method- ordered or random
E+A+B - EAB- ECD-E+C+D

Pingpong method- covalent bonds are formed
EA-EC - C or E+B - EB

Question 27

What are the 4 general enzyme strategies?

Answer 27

1) Position the reactants correctly 4 interactions
2) Distort reactants so less stable
3) Stabilise transition states
4) Change environment to favour the reaction

Question 28

Can environmental conditions and inhibitors affect activity?

Answer 28

Yes