For instance, if we take an enzyme that contains an active site, and inside that active site, we have a catalytic amino acid, namely the cysteine, well, then this Idocidamide will react with that catalytic amino acid, the cysteine, to form a covalent bond between this carbon here and this sulfur atom here. And because this is the sulfur atom, part of the side chain of the cysteine, that is used to basically catalyze some specific type of reaction, because we form a covalent bond, as shown in the following diagram, that essentially deactivates and inhibits the activity of that particular enzyme. And so, as a result of this covalent modification, we essentially deactivate that active side of the enzyme. And notice in this process, we essentially kick off the I dye and we also break off that H atom. And so we form this molecule, as shown here. The H has a positive charge, the iodide has a negative charge.