Disulfide bonds. is that an answer?
A heart beat, breathing, and moving ;)
I believe it is organ level
Active site
A reactant
binds to an enzyme in a region known as the active site during a reaction. The active site is the
most important part of the enzyme because it is where the chemical reaction
happens. It usually contains three to four amino acids and a binding site that
binds the substrate and prepares it for catalysis.
