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Question on enzymes.

As silly and as simple as this question may sound I'm just looking for someone to clarify.

I know an enzyme is a biological catalyst and thus doesn't actually allow a reaction to occur rather it alters the rate at which it takes place. However, it is often referred to that catalysts 'break down' the substrate molecules into smaller, more soluble products. In a process like the digestion of starch, would amylase breaking the starch down into maltose (a disaccharide) be classed as catalysing the whole digestion process as a whole? Or, does the enzyme speed up the hydrolysis of the starch another method and thus doesn't directly 'break it down'?

Thanks in advance.

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Original post by Kozmo
As silly and as simple as this question may sound I'm just looking for someone to clarify.

I know an enzyme is a biological catalyst and thus doesn't actually allow a reaction to occur rather it alters the rate at which it takes place. However, it is often referred to that catalysts 'break down' the substrate molecules into smaller, more soluble products. In a process like the digestion of starch, would amylase breaking the starch down into maltose (a disaccharide) be classed as catalysing the whole digestion process as a whole? Or, does the enzyme speed up the hydrolysis of the starch another method and thus doesn't directly 'break it down'?

Thanks in advance.

The active site of enzyme amalyse attached to the substrate molecule(in this case starch). This forms an enzyme substrate complex which later forms into the products which is the disaccarides maltose(sorry for spelling). Basically the amylase speeds up the hydrolysis of starch- splitting it using a water molecule to form its components. It speeds it up but doesnt get used up.it does it by lowering the activation level and breaks it down.
(edited 8 years ago)
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Original post by parrot16
The active site of enzyme amalyse attached to the substrate molecule(in this case starch). This forms an enzyme substrate complex which later forms into the products which is the disaccarides maltose(sorry for spelling). Basically the amylase speeds up the hydrolysis of starch- splitting it using a water molecule to form its components. It speeds it up but doesnt get used up.it does it by lowering the activation level and breaks it down.


Yea, I know all of that, but I'm curious whether the enzyme physically 'breaks it down' and this is the catalytic process or whether it aids hydrolysis in another way?
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Original post by Kozmo
Yea, I know all of that, but I'm curious whether the enzyme physically 'breaks it down' and this is the catalytic process or whether it aids hydrolysis in another way?


The enzyme breaks the starch down into maltose and hydrolysis will break the maltose into its constituent monosaccharides - ie two alpha glucose monomers.
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Original post by jamestg
The enzyme breaks the starch down into maltose and hydrolysis will break the maltose into its constituent monosaccharides - ie two alpha glucose monomers.


Thank you! Do you know the process by which the enzyme breaks down the starch into maltose? My curiosity is endless, sorry 😂
Original post by Kozmo
Yea, I know all of that, but I'm curious whether the enzyme physically 'breaks it down' and this is the catalytic process or whether it aids hydrolysis in another way?


aids in hydrolysis.
Original post by Kozmo
Thank you! Do you know the process by which the enzyme breaks down the starch into maltose? My curiosity is endless, sorry 😂

Condensation reaction I think.
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Original post by Kozmo
Thank you! Do you know the process by which the enzyme breaks down the starch into maltose? My curiosity is endless, sorry 😂


Catalysed hydrolysis reaction
Hydrolysis, it wont be condensation since we are breaking it into it constituent monosaccharides
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Original post by parrot16
aids in hydrolysis.


Original post by jamestg
Catalysed hydrolysis reaction


Original post by mhussain23
Hydrolysis, it wont be condensation since we are breaking it into it constituent monosaccharides


So, what I've gathered thus far is that the enzyme doesn't physically 'break down the substrate', but rather aids in the hydrolysis of that substrate, in our example, starch. But how does it do this? I know the induced fit model of the enzyme explains how the bonds are put under pressure and so an alternative path and therefore a lower activation energy can be obtained, but what actually hydrolyses the substrates once they've formed the enzyme-substrate complex?
Original post by Kozmo
So, what I've gathered thus far is that the enzyme doesn't physically 'break down the substrate', but rather aids in the hydrolysis of that substrate, in our example, starch. But how does it do this? I know the induced fit model of the enzyme explains how the bonds are put under pressure and so an alternative path and therefore a lower activation energy can be obtained, but what actually hydrolyses the substrates once they've formed the enzyme-substrate complex?


Water molecules?
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Original post by jamestg
Water molecules?


Yea, of course, but how does that occur? Is there a particular mechanism that encourages the hydrolysis process (that would indeed make sense)? Or is it by sheer chance?

I know this isn't on the spec, but I'm just curious!
Original post by Kozmo
Yea, of course, but how does that occur? Is there a particular mechanism that encourages the hydrolysis process (that would indeed make sense)? Or is it by sheer chance?

I know this isn't on the spec, but I'm just curious!


The collision of the water molecule with the disaccharide?
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Original post by jamestg
The collision of the water molecule with the disaccharide?


Yes, but my whole question and ideology is that there must be something which encourages that collision (the hydrolysis), and I'm wondering what that is.
I mean, obviously, the catalyst lowers the activation energy needed for this particular form of reaction (hydrolysis of the polysaccharide) to occur, but how does the hydrolysis come about, what prompts it, so to say.
(edited 8 years ago)
Original post by Kozmo
Yes, but my whole question and ideology is that there must be something which encourages that collision (the hydrolysis), and I'm wondering what that is.


I'm guessing the temperature? You'd add dilute HCl, put it in a water bath for 5mins and then add something to neutralise it (can't remember the exact solution) and then it will hydrolyse it.
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Original post by jamestg
I'm guessing the temperature? You'd add dilute HCl, put it in a water bath for 5mins and then add something to neutralise it (can't remember the exact solution) and then it will hydrolyse it.


With that in mind, it must just be down to random collisions between the water molecules and the poly/disaccharide. The enzyme (amylase), lowers the activation energy for a reaction by offering an alternate path for the bonds to be broken/made and so there's a much greater likelihood of a water molecule and substrate colliding AND reacting with one another and thus hydrolysing the carbohydrate.

This, or the enzyme having some form of water molecule storage is the only conclusion I can think of. The former seems more probable. I'll check with my teacher(s) monday though :tongue:
Original post by Kozmo
With that in mind, it must just be down to random collisions between the water molecules and the poly/disaccharide. The enzyme (amylase), lowers the activation energy for a reaction by offering an alternate path for the bonds to be broken/made and so there's a much greater likelihood of a water molecule and substrate colliding AND reacting with one another and thus hydrolysing the carbohydrate.

This, or the enzyme having some form of water molecule storage is the only conclusion I can think of. The former seems more probable. I'll check with my teacher(s) monday though :tongue:


I think think correct.:smile:
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IzzieXOX
Original post by Kozmo
Yes, but my whole question and ideology is that there must be something which encourages that collision (the hydrolysis), and I'm wondering what that is.
I mean, obviously, the catalyst lowers the activation energy needed for this particular form of reaction (hydrolysis of the polysaccharide) to occur, but how does the hydrolysis come about, what prompts it, so to say.


The hydrogen bonds in the quarternary structure of the enzyme, a globular protein, react with the substrate. This occurs in the substrate-enzyme complex and results in the breakdown of the substrate
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Original post by IzzieXOX
The hydrogen bonds in the quarternary structure of the enzyme, a globular protein, react with the substrate. This occurs in the substrate-enzyme complex and results in the breakdown of the substrate


An enzyme is a tertiary structure? Also, I'm pretty sure this is wrong as it implies that the enzyme does the reaction as opposed to catalyses it.

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