Q.
A sample of an enzyme called lactase was isolated from the intestinal lining of a calf. Assays were undertaken to evaluate the activity of the enzyme sample.
The substrate of lactase is the disaccharide lactose. Lactase breaks a lactose molecule in two, producing a glucose molecule and a galactose molecule.
Two assays were carried out.
Assay -$ 1$
Lactose concentration (% W/v)
15
15
15
15
15
15
Concentration of enzyme sample (5 v/v)
0
5
10
15
20
25
Reaction rate $\mu$ mole glucose $sec^{-1} mL^{-1}$
0
25
50
75
100
125
Assay - 2
Lactose concentration (% W/v)
0
5
15
20
25
30
Concentration of enzyme sample (5 v/v)
5
5
5
5
5
5
Reaction rate $\mu$ mole glucose $sec^{-1} mL^{-1}$
0
15
25
35
40
40
Which of the following assays would you expect to have the highest reaction rate?
$\,\,\,$
Lactose concentration (% w /v )$\,\,\,$
Concentration of enzyme sample
(% v/v)
(a)$\,\,\,$
15$\,\,\,$
5$\,\,\,$
(b)
30$\,\,\,$
5$\,\,\,$
(c)
15$\,\,\,$
25$\,\,\,$
(d)
30$\,\,\,$
25$\,\,\,$
| Lactose concentration (% W/v) | 15 | 15 | 15 | 15 | 15 | 15 |
| Concentration of enzyme sample (5 v/v) | 0 | 5 | 10 | 15 | 20 | 25 |
| Reaction rate $\mu$ mole glucose $sec^{-1} mL^{-1}$ | 0 | 25 | 50 | 75 | 100 | 125 |
| Lactose concentration (% W/v) | 0 | 5 | 15 | 20 | 25 | 30 |
| Concentration of enzyme sample (5 v/v) | 5 | 5 | 5 | 5 | 5 | 5 |
| Reaction rate $\mu$ mole glucose $sec^{-1} mL^{-1}$ | 0 | 15 | 25 | 35 | 40 | 40 |
| $\,\,\,$ | Lactose concentration (% w /v )$\,\,\,$ | Concentration of enzyme sample (% v/v) |
|---|---|---|
| (a)$\,\,\,$ | 15$\,\,\,$ | 5$\,\,\,$ |
| (b) | 30$\,\,\,$ | 5$\,\,\,$ |
| (c) | 15$\,\,\,$ | 25$\,\,\,$ |
| (d) | 30$\,\,\,$ | 25$\,\,\,$ |
Biomolecules
Solution: