image: The FeMo cofactor is the catalytically active metal cluster in the enzyme nitrogenase that converts atmospheric dinitrogen into bioavailable ammonium. It is the largest and most complex metal site known in biology, and the chemical nature of its central atom (C, N or O) has been under debate for many years. In this paper, the researchers have characterized the structure of nitrogenase at atomic resolution and conducted electron paramagnetic resonance spectroscopy experiments. The new data allow for an identification of the central atom as a carbon and provide valuable clues for understanding the functionality and biogenesis of FeMo cofactor. This image relates to a paper that appeared in the Nov. 18, 2011, issue of Science, published by AAAS. The paper, by T. Spatzal at Albert-Ludwigs-Universität Freiburg in Freiburg, Germany, and colleagues, was titled, “Evidence for Interstitial Carbon in Nitrogenase FeMo Cofactor.” view more
Credit: Image copyright Science/AAAS