An apoenzyme is the inactive storage and generally secretory form of a protein.
From the en.wikipedia.org
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A protein that combines with a coenzyme to form an active enzyme
Enzymes are proteins that catalyze (i.e., increase the rates of) chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. ...
An inactive haloenzyme lacking a cofactor
The protein part of an enzyme that requires a covalently bound coenzyme (a low molecular weight organic compound) or a cofactor (such as a metal ion) for activity