As you are most certainly aware, one of the goals of embalming is temporary preservation. This accomplished is in part by stabilizing proteins.  Without getting into the chemical pathways this stabilization can be achieved through the neutralization of enzymatic proteins that will digest other proteins.  In regard to neutralization of enzymes it’s sort of a two birds one stone effect, stabilize and neutralize a protein all at once.  Enzymes are regulated in a multitude of ways.  This is a great launching off point for our mnemonic for proenzymes.

Proenzymes are the precursors of enzymes, a change is required to activate them. In a biological system it’s sometimes more effective, quicker really, to have enzymes ready to go but not active than it is to synthesize them on the fly.  Usually, activation occurs by hydrolysis of an inhibiting fragment that masks an active site. Examples of proenzymes are pepsinogen and trypsinogen.  These are digestive enzymes that we don’t want to be active when there is no food to digest in our stomach but can be quickly activated when needed.  In my mind proenzymes are like a wheel lock that immobilizes a car. The car can’t move with it on but functions fine when the lock is off.

I think of proenzymes as “pre”enzymzes.  The mnemonic for the day is the pro/pre swap for proenzymes.

Imagine if these enzymes were perpetually active and unregulated!  We’d digest ourselves!! Its much safer to have them in the “PROcursor” form.