In biology, the active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction. The active site consists of residues that form temporary bonds with the substrate (binding site) and residues that catalyse a reaction of that substrate (catalytic site). The active site is usually a groove or pocket of the enzyme which can be located in a deep tunnel within the enzyme, or between the interfaces of multimeric enzymes. An active site can catalyse a reaction repeatedly as its residues are not altered at the end of the reaction (they may change during the reaction, but are regenerated by the end).
Usually, an enzyme molecule has only one active site, and the active site fits with one specific type of substrate. An active site contains a binding site that binds the substrate and orients it for catalysis. Residues in the binding site form hydrogen bonds, hydrophobic interactions, or temporary covalent interactions (van der Waals) with the substrate to make an enzyme-substrate complex. In order to function, the active site needs to be in a specific conformation and so denaturation of the protein by high temperatures or extreme pH values will destroy its catalytic activity. A tighter fit between an active site and the substrate molecule is believed to increase efficiency of a reaction. Most enzymes have deeply buried active sites, which can be accessed by a substrate via access channels.
Our pulse to resist
Moves our cultural resistance
I'm living this life
Inside a civil tribe demised
Improve my old mind
Breaking all rules, absorbing what I may find
Our manner to protect
Destroys what's left for protection
Believing in symbols
The church will fool our souls
Prove you my role
Acting against undesired control
Don't fear your left
Don't trust your right
Activist
Our way of seeing progress
Makes us walk towards repression
Disturbing our peace
In the name of self defense
Being felt by all
Our violent taste for the humans fall
Don't fear your left
Don't trust your right