1. The protein component of an enzyme that lacks its cofactor or prosthetic group and is therefore catalytically inactive.
Usage: biochemistry; technical

Examples

• The apoenzyme cannot catalyze reactions until it binds with its required cofactor.
• When the metal ion is removed from the holoenzyme, the remaining apoenzyme is inactive.
• Researchers studied how the apoenzyme changes shape upon cofactor binding.
• The apoenzyme and its coenzyme together form the complete, functional holoenzyme.
• Without its prosthetic group, the apoenzyme lacks catalytic activity.