Question

Nitrogenase enzymes structure and properties

Answer 1

Structure

The equilibrium formation of ammonia from molecular hydrogen and nitrogen has an overall negative enthalpy of reaction ({\displaystyle \Delta H^{0}=-45.2\ \mathrm {kJ} \,\mathrm {mol^{-1}} \;\mathrm {NH_{3}} }), the activation energy is very high ({\displaystyle E_{\mathrm {A} }=230-420\ \mathrm {kJ} \,\mathrm {mol^{-1}} }).[1]Nitrogenase acts as a catalyst, reducing this energy barrier such that the reaction can take place at ambient temperatures.

The nitrogenase complex consists of two proteins:

The homodimeric Fe protein, a reductasewhich has a high reducing power and is responsible for the supply of electrons.

The heterotetrameric MoFe protein, a nitrogenase which uses the electrons provided to reduce N2 to NH3.

Answer 2

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Enzymes are biological molecules that act as catalysts. They help speed up the rate of chemical reactions that take place inside the cells of living organisms by lowering the activation free energy.

                                           

Nitrogenase acts as a catalyst, reducing this energy barrier such that the reaction can take place at ambient temperatures.

The nitrogenase complex consists of two proteins:

The homodimeric Fe protein, a reductasewhich has a high reducing power and is responsible for the supply of electrons.

The heterotetrameric MoFe protein, a nitrogenase which uses the electrons provided to reduce N2 to NH3.