Vanadium Nitrogenase

Abstract

Biological nitrogen fixation is one of the most important enzymatic reactions in Nature. It is, therefore, understandable that the tremendous environmental need for this reaction has created backup or alternative nitrogen-fixing systems. To date, four nitrogenase systems have been identified to exist in bacteria and archea. Although the majority of known nitrogen-fixing organisms have an enzyme system based on Mo and Fe, alternative systems have been found that are based either on V and Fe or on Fe alone. Most important, all of these enzyme systems are genetically and biochemically distinct. There are many excellent reviews on alternative nitrogenases and the reader is encouraged to read these articles for more completeness (Bishop and Premakumar, 1992; Eady, 1996; Eady et al., 1990; Smith and Eady, 1992). This chapter will focus primarily on information gained during the past five years, but will include an overview of the structural, spectroscopic, enzymatic, and genetic differences of these systems.