Like a revealing biography of an elusive celebrity, a workshop at arecent meeting of the American Chemical Society provided the most detailed glimpses yet of the chemical structure of an enzyme called nitrogenase. Nitrogenase converts nitrogen from the air into a biologically useful form at room temperature and atmospheric pressures. In a recent news article on the meeting, Science magazine called nitrogenase "a powerful co-star (to nitrogen) on the biological stage." Although nitrogen is important to all forms of life, only a few species of microorganisms can turn atmospheric nitrogen into ammonia and compounds necessary for life. By simulating this natural nitrogenase system, researchers hope to develop eventually a simpler, cheaper way of providing ammonia salts for fertilizer, especially important for agriculture in developing countries. Using X-ray crystallography, two groups of researchers found similar, if slightly out-of-focus, portraits of the nitrogenase molecule at rest in its crystal form, an important first step in understanding how nitrogenase works its behind-the-scenes magic. The enzyme apparently contains chunks of iron, sulfur and molybdenum surrounded by a protein scaffolding. UC Davis chemist Stephen P. Cramer and his colleagues are using another technique -- X-ray absorption -- to fine-tune the focus on the active atomic players of the nitrogenase model. Useful for close-up looks, X-ray absorption can not only measure the distances between iron atoms with more precision, it can measure the active states of the nitrogenase molecule, according to Cramer, a professor of applied science. Findings by Cramer, UC Davis colleagues and other collaborators have sharpened the focus on the arrangement of metal atoms within the nitrogenase.