ENZYME LEC 2

Question 1

Cofactor?

Answer 1

Small molecule required by an enzyme to function

Question 2

Coenzyme?

Answer 2

Cofactor- metal ions or organic molecules

Question 3

Cosubstrate ?

Answer 3

cofactor which is Transiently associated with an enzyme

Question 4

Prosthetic group

Answer 4

A cofactor which is associated with an enzyme

Question 5

Holoenzyme

Answer 5

Is a cofactor enzyme complex which is active

Question 6

Apoenzyme

Answer 6

a cofactor enzyme complex which is inactive

Question 7

Cofactor consumption example

Answer 7

Vitamins

Question 8

Lipid soluble vitamins ?

Answer 8

A and D

Question 9

example In which coenzymes take place in catalysis in the citric acid cycle

Answer 9

thiamine pyrophosphate

Question 10

Enzyme assay?

Answer 10

Way in which we can measure the rate of an enzyme controlled reaction

Question 11

How can we measure the initial rate of a reaction?

Answer 11

product formation or substate disappearance

Question 12

Rate units

Answer 12

micromol/min

Question 13

enzyme unit?

Answer 13

1micromol/min (product)

Question 14

Katal?

Answer 14

1mol/sec

Question 15

Spectrophotometer? Example

Answer 15

Measure the light absorbance. Eg NAD+ absorbs at 340nm

Question 16

discontinuous direct assay?

Answer 16

Stop reaction at particular points and measure either [P] OR [R]

Question 17

Hardings test?

Answer 17

test for glucose
-reduces CuSO4 to Cu2O when boiled in alkaline solution
- Reaction of Cu2o with molybdate > green
Again use of spectrophotometer

Question 18

Coupled assay issue with measuring enzyme activity?

Answer 18

Product from one reaction being used as a substate in the next reaction so it cannot be measured

Question 19

direct assay

Answer 19

can measure rate of reaction (enzyme activity) through out, eg spectrophotometer volume of coloured solution formed being proportional to concentration present.

Question 20

Coupled assay solution to problem?

Answer 20

2nd product measured. 2nd enzyme mist be in excess (so rate limiting step is the one to be measured)

Question 21

Enzyme kinetics?

Answer 21

The effect certain reaction parameters have on a particular reaction

Question 22

Hyperbolic reaction?

Answer 22

Is the rate relationship described by Micheal mentor

Question 23

Parameters tested?- Enzyme kinetics ?

Answer 23

How sensitive a substrate ism how fast its metabolised

- Regulation of the enzyme?

Question 24

Vo =

Answer 24

Initial rate of reaction

Question 25

Micheal mentor time?

Answer 25

1913

Question 26

Micheal menton equation

Answer 26

V= Vmax (s)/ Km[s]

Question 27

Km value

Answer 27

the [s] in which the initial rate is Half its maximum

Question 28

Assumptions made by Micheal Mentons model?

Answer 28

1. S E+P step is irreversible

3. [ES] Is in a steady state

Question 29

The greater the Km value?

Answer 29

The greater the enzymes affinity for the substrate

Question 30

Kn?

Answer 30

Represents the rate constant for the nth step fo a reaction. Reverse is k-n

Question 31

Km alters with

Answer 31

Temp and pH

Question 32

K2?

Answer 32

Turner over number of Kcat

Question 33

Vmax=..

equation

Answer 33

K2[Et]\Kcat[Et]

Question 34

Units for Vmax, [S], Kcat

Answer 34

[P]/Time, Molar, time^-1

Question 35

Carbonic anhydrase has a large

Answer 35

Kcat

Question 36

Lineweaver-burk plot

Answer 36

Linnear Micheal mentons graph. 1 over everything

1/Vo= (Km/Vmax)(1/s) + 1/Vmax

Question 37

Points:

1) 1/vmax
2) 1/-Km
3) Gradient?

x axis
y axis

Answer 37

1) y intersect
2) x intersect
3) Km/Vmax
x axis- 1[s]
y axis 1/Vo

think y= mx+c

Question 38

Problems with lineweaver-burk plot?

Answer 38

1) Large values of [s] (most) are hard to detect (crowded on the left side of the graph as it 1/[s]
2) Small values of [s], small errors lead to large errors in 1/Vo and therefore large errors In Km and Vmax

Question 39

Hanes-Woolf Plot

Answer 39

[s] plotted against [s]/Vo

Question 40

Hanes-woolf plot equation

Answer 40

[S]/Vo= Km/Vmax +[S]/Vmax 
Mx= [S]/Vmax