What is the difference between holoenzyme and apoenzyme

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Area of ‚Äč‚ÄčExpertise - biochemistry

Many enzymes require a coenzyme in order to be catalytically effective. The pure enzyme protein without coenzyme is called apoenzyme. The enzyme is not active in this form. If the appropriate coenzyme is added, the apoenzyme becomes the catalytically active holoenzyme. If the coenzyme is non-covalently bound, it can often easily be separated off by means of gel filtration or dialysis and in this way the holoenzyme can be converted into the apoenzyme.

For example, dehydrogenases generally require a coenzyme that acts as an electron carrier. The dehydrogenase as such represents the apoenzyme. Together with the coenzyme (e.g. NAD1) as electron carrier) the dehydrogenase is present as a holoenzyme and can catalyze the reaction.

Learning units in which the term is dealt with

Enzymes60 min.


The basics of an enzymatic reaction are described, as well as the basic characteristics of enzymes. The active center is explained as well as the key-lock principle or the induced fit. In addition, the terms apoenzyme and holoenzyme and isoenzyme or alloenzyme are explained.

Oxidoreductases90 min.

biochemistrymetabolismEnzymes and enzyme classes

Description of the characteristics of an enzymatic reaction catalyzed by oxidoreductases. Examples of oxidoreductases.

Enzyme Regulation - Introduction30 min.


General principles of the regulation of an enzyme are explained, including ways of influencing the enzyme conformation and concentration and multi-enzyme complexes.