why is a lock and key used to describe the way an enzyme works.?

Question

Also describe any ways in which the analogy is not perfect?

Answer 1

It was initially thought that enzyme was a rigid macromolecule.
But it is actually a flexible molecule which undergoes a conformational change once the substrate finds entry into the active site. In fact the substrate induces the enzyme to undergo a conformational change to a state when it is catalytically favorable but thermodynamically unstable. What this means is that the key makes the lock adjust its groove and when the key is not used the lock has different groove.

Answer 2

The earlier answerer explained the reason behind 'the lock and key' mechanism, basically the idea is: Enzymes have highly specific active sites which only fit certain specific substrates.

This analogy is actually very misleading, (though I think they still mention it even at degree level) a closer approximation of what generally occurs during enzyme activity is the 'induced fit' mechanism. An enzyme acitve site recognises the substrate and the active site changes conformation around the enzyme leading to catalysis.

Again this model is far from perfect but it gives a better general understanding of what is actually occuring.

Edit- conformation means shape and active site is the area of the enzyme that binds to the substrate. (Not sure what level Biology you are so I thought I should add in these definitions for you).

Answer 3

I am not positively sure but I know the general idea; enzymes have receptor or active sites that are a certain shape, and when a molecule wants to interact with it, it has to be the same shape which allows for 'communication.' As in the door/key example, the key has a certain shape that will 'communicate' with the lock on the door to open it up. Hopefully I made sense!

Answer 4

it is called a lock and key model because there is only one substrate that will fit into the active site of an enzyme. Just like the keys of a car, even if you have the same make and model of one car, the key to the same car will not open the other car although it is the same.

Answer 5

It is because certain enzymes can only work with certain, um, chemicals. I forgot the name of the compound enzymes work with. But it's like a lock and a key. Certain locks can only work with certain keys.

I suppose it wouldn't be perfect because a guy could pick a lock.

P.S.: Substrate, that's the word. Thanks Ashlie!

Answer 6

i was literay given this exact question on a take home exam in 9th grade.

Answer 7

Hi Linda,

This sounds a little bit too much like aquestion from a take-home exam. :+(

If this is not the case I apologise.