, or extracellular enzyme
, is an enzyme
that is secreted by a cell
and that works outside that cell
. It is usually used for breaking up large molecules that would not be able to enter the cell otherwise. It is an enzyme that organisms secrete into the environment which acts outside the microbe. The opposite of an exoenzyme is called an endoenzyme
This term is also often used to refer to the hydrolytic digestive enzymes secreted by fungi.