Enzymes are complex nitrogenous organic compounds produced by living plants and animals. They are protein molecules of high molecular mass that form colloidal solutions in water.
They act as highly efficient catalysts for numerous reactions,especially those associated with natural biological processes. Because they catalyze reactions within living organisms,they are termed biochemical catalysts,and the phenomenon is known as biochemical catalysis.
Examples of enzyme-catalyzed reactions:
$(i)$ Inversion of cane sugar: The enzyme invertase converts cane sugar into glucose and fructose.
$C_{12}H_{22}O_{11(aq)} + H_2O_{(l)} \xrightarrow{\text{Invertase}} C_6H_{12}O_{6(aq)} + C_6H_{12}O_{6(aq)}$
$(ii)$ Conversion of glucose into ethyl alcohol: The enzyme zymase converts glucose into ethyl alcohol and carbon dioxide.
$C_6H_{12}O_{6(aq)} \xrightarrow{\text{Zymase}} 2C_2H_5OH_{(aq)} + 2CO_{2(g)}$
$(iii)$ Conversion of starch into maltose: The enzyme diastase converts starch into maltose.
$2(C_6H_{10}O_5)_{n(aq)} + nH_2O_{(l)} \xrightarrow{\text{Diastase}} nC_{12}H_{22}O_{11(aq)}$
$(iv)$ Decomposition of urea: The enzyme urease catalyzes the decomposition of urea into ammonia and carbon dioxide.
$NH_2CONH_{2(aq)} + H_2O_{(l)} \xrightarrow{\text{Urease}} 2NH_{3(g)} + CO_{2(g)}$