Deoxyribonuclease active center

Some enzymes are rendered inactive by specific or unspecific inhibitors, as in the case of ribonuclease and deoxyribonuclease. Other enzymes have latent activity because their active center is in some way inactivated by some polypeptidic chain in the molecule. Once the inhibiting chain has been removed by the action of proteolytic enzymes, the enzyme becomes fully active, as is the case for example, for thrombin and chymotrypsin. Finally, the activity of some enzymes is kept latent because of the absence of a cofactor e.g., phenylpyruvic hydroxylase in the developing liver). 

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