ectoenzyme ec·to·en·zyme (ěk'tō-ěn'zīm)
n.
An enzyme situated on the outer surface of a cell's membrane so that its active site is available to the exterior environment of the cell.
Extracellular enzyme.
exoenzyme ex·o·en·zyme (ěk'sō-ěn'zīm')
n.
See extracellular enzyme.