What is an active site?

Memory Hack💡

The active site is where all of the "activity" happens, aka, where the substrate will be acted upon. I think of a bunch of little molecules in construction hats working hard to modify the substrate! It is silly, but it gets stuck in my head!!

Notes

The active site is where the substrate binds to the enzyme. 

When we talk about the active site, it is common to give the example of the "lock and key" model or the "induced fit model". 

Lets look into this lock and key model a bit closer… 

When we say that a substrate binds into an enzyme like a “lock and key” we are suggesting that and enzyme has a very specific rigid shape that is only able to be bound by something of the complementary very specific shape. However, this model tends to ignore a lot of how enzyme active sites actually work. 

While yes, they are specific to their substrate, it is not necessarily because they fit in perfectly. Instead, they follow a more induced fit model. This means that they will bind to the active site, but as the substrate binds, it may cause conformational changes in the enzyme that allow it to bind fully together.