CHAPTER 11 - Molybdenum in Nitrogenase

Abstract

Nitrogen fixation ranks with photosynthesis as a process of fundamental importance to all life on earth. The biochemical process described by nitrogen fixation is the reduction of N2 to NH3, which can then be used for the synthesis of amino acids, nucleic acids, and other essential nitrogenous compounds. Intensive agricultural methods have led to increased use of and dependence on manufactured nitrogenous fertilizers with decreased emphasis on biological nitrogen fixation. However, with the depletion of fossil fuels, the cost of fertilizer production is rising, and this situation could easily lead to a worldwide food crisis. One aspect of nitrogen fixation that is receiving an increased amount of interest is the role of the element molybdenum. The enzyme nitrogenase that catalyzes the reduction of N2 to NH3 is one of a handful of enzymes that relies absolutely on Mo for catalytic activity. This fact has practical significance for agriculture since certain soils that could just barely support the growth of nitrogen-fixing legumes and could be greatly improved simply by addition of trace levels of Mo.