<Li> Where S is substrate, P is product and C is catalyst . </Li> <P> In biochemistry, the substrate is a molecule upon which an enzyme acts . Enzymes catalyze chemical reactions involving the substrate (s). In the case of a single substrate, the substrate bonds with the enzyme active site, and an enzyme - substrate complex is formed . The substrate is transformed into one or more products, which are then released from the active site . The active site is then free to accept another substrate molecule . In the case of more than one substrate, these may bind in a particular order to the active site, before reacting together to produce products . A substrate is called' chromogenic' if it gives rise to a coloured product when acted on by an enzyme . In histological enzyme localization studies, the colored product of enzyme action can be viewed under a microscope, in thin sections of biological tissues . Similarly, a substrate is called' fluorogenic' if it gives rise to a fluorescent product when acted on by an enzyme . </P> <P> For example, curd formation (rennet coagulation) is a reaction that occurs upon adding the enzyme rennin to milk . In this reaction, the substrate is a milk protein (e.g., casein) and the enzyme is rennin . The products are two polypeptides that have been formed by the cleavage of the larger peptide substrate . Another example is the chemical decomposition of hydrogen peroxide carried out by the enzyme catalase . As enzymes are catalysts, they are not changed by the reactions they carry out . The substrate (s), however, is / are converted to product (s). Here, hydrogen peroxide is converted to water and oxygen gas . </P> <Dl> <Dd> E + S ↽ − − ⇀ ES ⟶ EP ↽ − − ⇀ E + P (\ displaystyle (\ ce ((E) + S <=> ES -> EP <=> (E) + P))) </Dd> </Dl>

Hydrogen peroxide is the substrate for which enzyme