Consider the simple reaction of nitrogen to make ammonia:
About half of the world's production of ammonia is carried out industrially and half biologically. At first glance, the two processes look quite different. The industrial reaction takes place at 500°C. and uses gaseous hydrogen and a metal catalyst under high pressure. The biological reaction takes place in the soil, uses bacterial or plant reactors, and occurs at moderate temperature and normal atmospheric pressure of nitrogen. These differences are so substantial that, historically, they were interpreted by supposing that biological systems are infused with a vital spirit that makes life possible. However, the biological reaction can be done with a purified enzyme. The biological reduction of nitrogen is more similar to than different from its industrial counterpart: The energy change from synthesis of a mole of ammonia is identical in both cases, the substrates are the same, and the detailed chemical reaction is similar whether the catalyst is a metal or the active site of an enzyme.