Repressors don't actually *do* anything in the enzyme's active site. That's the key point: repressors don't bind to the active site.

Here's why:

* Repressors regulate gene expression: Repressors are proteins that bind to specific DNA sequences called operator sites located near the genes they regulate. This binding prevents the gene from being transcribed into mRNA, thus preventing the production of the corresponding protein.

* Active site is for substrate binding: The active site is a specific region on an enzyme where the substrate (the molecule the enzyme acts upon) binds. It's where the catalytic reaction takes place.

So, repressors and active sites have separate functions:

* Repressors: Control the *production* of enzymes by preventing transcription.

* Active sites: Facilitate the *activity* of enzymes by binding substrates.

In short: Repressors are involved in gene regulation, while active sites are involved in enzymatic catalysis. They are distinct and unrelated processes.