Immobilising enzymes question!?

Can anyone explain why this trend is such? I would have thought it would have gone the other way around?!

Thanks :biggrin:

The enzyme lactase (β-galactosidase) catalyses the hydrolysis of lactose to glucose and galactose. Lactase was immobilised and the beads were placed in a column.Lactose solution was poured through the column and the solution dripping from the column was tested with a glucose-testing strip. Glucose causes the test strip to turn blue.The time taken to obtain a standard blue colour was recorded.The experiment was repeated with different concentrations of lactose. The results are shown in the table below.

Lactose concentration 1 mol dm^–3 __0.01__0.05 __0.10__0.15 ___0.20
Time for standard blue colour / s ____340___65 ___35 ____25 ____25

(edited 8 years ago)

Reply 1

RMNDK

3

Original post by Funky_Giraffe

Can anyone explain why this trend is such? I would have thought it would have gone the other way around?!

Thanks :biggrin:

The enzyme lactase (β-galactosidase) catalyses the hydrolysis of lactose to glucose and galactose. Lactase was immobilised and the beads were placed in a column.Lactose solution was poured through the column and the solution dripping from the column was tested with a glucose-testing strip. Glucose causes the test strip to turn blue.The time taken to obtain a standard blue colour was recorded.The experiment was repeated with different concentrations of lactose. The results are shown in the table below.

Lactose concentration 1 mol dm^–3 __0.01__0.05 __0.10__0.15 ___0.20
Time for standard blue colour / s ____340___65 ___35 ____25 ____25

Why do you think the trend should go the other way around?

Reply 2

Funky_Giraffe

OP

10

Original post by RMNDK

Why do you think the trend should go the other way around?

I would have thought that the more concentrated the lactose, the longer it would take for lactase to break it down, rather than the other way round.

Reply 3

Zwitterion1

6

Original post by Funky_Giraffe

I would have thought that the more concentrated the lactose, the longer it would take for lactase to break it down, rather than the other way round.

Increasing concentration of substrate increases rate of reaction

Reply 4

RMNDK

3

Original post by Funky_Giraffe

I would have thought that the more concentrated the lactose, the longer it would take for lactase to break it down, rather than the other way round.

Why do you think that?

Reply 5

RDB1826

10

I think it's a good idea to remind ourselves that there is a fixed amount of enzyme in the column. Now, realistically we need a substantial/threshold level of glucose in order to 'see' a blue colour appear. So, if we increase the concentration of lactose going through the column, the more enzyme-substrate complexes will form (faster rate of reaction) in the column (until saturation point). This means, in a shorter amount of time (i.e. less volume of lactose solution required) more glucose (and galactose) will be produced from enzymatic action. This, in turn, means a blue colour will 'appear' more quickly.

Does that make sense?

Reply 6

Funky_Giraffe

OP

10

Original post by RDB1826

I think it's a good idea to remind ourselves that there is a fixed amount of enzyme in the column. Now, realistically we need a substantial/threshold level of glucose in order to 'see' a blue colour appear. So, if we increase the concentration of lactose going through the column, the more enzyme-substrate complexes will form (faster rate of reaction) in the column (until saturation point). This means, in a shorter amount of time (i.e. less volume of lactose solution required) more glucose (and galactose) will be produced from enzymatic action. This, in turn, means a blue colour will 'appear' more quickly.

Does that make sense?

Ahh I see. Thanks very much for explaining!

Reply 7

Funky_Giraffe

OP

10

Original post by RDB1826

I think it's a good idea to remind ourselves that there is a fixed amount of enzyme in the column. Now, realistically we need a substantial/threshold level of glucose in order to 'see' a blue colour appear. So, if we increase the concentration of lactose going through the column, the more enzyme-substrate complexes will form (faster rate of reaction) in the column (until saturation point). This means, in a shorter amount of time (i.e. less volume of lactose solution required) more glucose (and galactose) will be produced from enzymatic action. This, in turn, means a blue colour will 'appear' more quickly.

Does that make sense?

Can I just ask, what things do you need to keep constant? I have already said temp and SA of beads but I need one more. Could it be pH?