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Non Life Sciences => Chemistry => Topic started by: scientizscht on 06/08/2020 14:13:53

Title: Does enzyme immobilisation result in increase or decrease of reactivity?
Post by: scientizscht on 06/08/2020 14:13:53
Hello

Does enzyme immobilisation result in increase or decrease of reactivity?

I find contradicting references.

Thanks
Title: Re: Does enzyme immobilisation result in increase or decrease of reactivity?
Post by: Bored chemist on 06/08/2020 15:21:14
Does enzyme immobilisation result in increase or decrease of reactivity?
What would you expect to find in the literature if the answer was "it depends on the details of the situation"?
Title: Re: Does enzyme immobilisation result in increase or decrease of reactivity?
Post by: evan_au on 06/08/2020 21:58:02
You need to apply the theory of relativity here: immobilization relative to what.

For an enzyme to catalyze a reaction, it needs to:
- dock with the reactants
- place the reactants in an environment where the target reaction is more favorable
- apply a source of energy (which may be random thermal motion, or in living things, may be powered by ATP)
- release the product after the reaction is complete

So:
- If the enzyme could not be immobilized relative to the reactants, it would not catalyze the reaction
- If the enzyme were immobilized relative to the reaction product, it would never catalyze another reaction

Bear in mind that in the real (quantum) world, molecules are not static things, but are wriggly, jiggly things that are always moving around, and are never completely immobilized, even at absolute zero...
Title: Re: Does enzyme immobilisation result in increase or decrease of reactivity?
Post by: Bored chemist on 06/08/2020 22:18:54
You need to apply the theory of relativity here
Not really.
You just need to know what an immobilized enzyme is
https://en.wikipedia.org/wiki/Immobilized_enzyme

Title: Re: Does enzyme immobilisation result in increase or decrease of reactivity?
Post by: evan_au on 08/08/2020 00:17:58
Quote from: Bored Chemist
You just need to know what an immobilized enzyme is
Thanks for the pointer...

If I read the description right...
- The enzymes are typically immobilized relative to a bead
- The beads are typically immobilized relative to the reaction chamber
- The beads are not immobilized relative to the working fluid, which can carry reactants into the reaction chamber, and the products out of the reaction chamber?
Title: Re: Does enzyme immobilisation result in increase or decrease of reactivity?
Post by: Bored chemist on 08/08/2020 12:24:37
I think that's right except the beads may be stirred within the reaction chamber.

In terms of pounds of product per day per pound of enzyme, the reaction rate is increased.
In terms of chemical kinetics the reaction rate is typically decreased.
Title: Re: Does enzyme immobilisation result in increase or decrease of reactivity?
Post by: scientizscht on 08/08/2020 14:20:29
I think that's right except the beads may be stirred within the reaction chamber.

In terms of pounds of product per day per pound of enzyme, the reaction rate is increased.
In terms of chemical kinetics the reaction rate is typically decreased.

Why exactly these two directly proportional rates are moving to the opposite direction?
Title: Re: Does enzyme immobilisation result in increase or decrease of reactivity?
Post by: Bored chemist on 08/08/2020 14:45:43
There's a point to immobilising enzymes.
If there wasn't then nobody would do it.

The reason is essentially that it's much easier to process.
For example, you can set up a process- you can imagine that I want to make alcohol.
I can do that in the conventional way - as a batch process.

But if I use an immobilised enzyme, I can use a continuous process.
Because I don't have to mess about filling and emptying tanks etc, I can get a much higher throughput.

So the question is why do you think they are
exactly these two directly proportional rates
?