Nitrogenase is the enzyme responsible for the ‘fixation’ of nearly inert atmospheric dinitrogen to ammonia.  It is ultimately responsible for half of the world’s protein, while the other half depends on industrial fertilizer produced with hydrogen derived from fossil fuels.  Another type of enzyme, hydrogenase, catalyzes the interconversion of dihydrogen with protons and electrons.  These enzymes use unusual forms of Fe-S clusters, and their catalytic mechanisms are not understood.<br/>Nuclear Resonance Vibrational Spectroscopy (NRVS) is a powerful tool for vibrational spectroscopy of Fe in these enzymes.  In this synchrotron radiation (SR) technique, a sample is excited with a ~1 meV bandwidth beam near the Mössbauer resonance, and the delayed fluorescence is recorded as a function of excitation energy.  When applied to Fe-containing samples, NRVS is only sensitive to vibrations involving motion of <sup>57</sup>Fe.  Infrared spectroscopy is a more conventional tool for vibrational spectroscopy.  Somewhat surprisingly, experiments in the IR regional can also benefit from synchrotron radiation.  Preliminary results from SR-IR will be compared with the NRVS findings.

N2ase & H2ase vibrational spectroscopy with NRVS & FT-IR: The merits of big photons & little ones

251st National Meeting (2016)

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