INFEWS N/P/H20: Supramolecular Recognition and Catalysis Targeting Phytate, an Organic Sink for Phosphate in the Human Phosphorus Cycle

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Depletion of the world's available supply of phosphorus has grown at alarming rates over the last seven decades. The dwindling phosphorus supplies negatively impact crop growth and agricultural sustainability. Chemists worldwide are focused on devising new molecular strategies to meet the food needs of a growing population. Professor Bowman-James and her students at the University of Kansas are focusing on gaining insight into phosphorus chemistry while addressing the adverse chemical issues associated with phytate, one of the key phosphorus-containing molecules found in soils. Broader impacts of this project include the training of undergraduate and graduate students at the University of Kansas, as well as international student exchanges. Collaborators include a soil scientist, Professor Ganga Hettiarachchi, at Kansas State University, and two international researchers, Professor Carlos Kremer at the University of the Republic in Uruguay, and Professor Antonio Bianchi at the University of Florence in Italy. Phytate (myo-inositol-1,2,3,4,5,6-hexakisphosphate) is a relatively small, but chemically complex, organic molecule loaded with six phosphates. It is a major scavenger of metal nutrients. Unfortunately, many of its salts with metal ion nutrients, such as iron, zinc, and calcium, are insoluble, resulting in its classification as an antinutrient. Phytate also holds a significant amount of much-needed phosphorus hostage within its molecular structure. With the support of the Macromolecular, Supramolecular and Nanochemistry Program of the NSF Chemistry Division, Prof. Bowman-James and coworkers are designing molecules to assist in releasing captured metal ion nutrients and to probe phytate?s phosphate chemistry. This research combines supramolecular host-guest and metal ion chemistry tactics to provide new ways to manipulate the physical and chemical properties of phytate. Goals are to gain a better understanding of phytate and phosphate chemistry at the molecular level. Aims 1 and 2 provide an in-depth structural profile of phytate and its different conformational forms. Nutrient insolubility and delivery issues are being addressed by using noncyclic and cyclic chelates to complex phytate via supramolecular hydrogen bond and electrostatic interactions, in addition to overcoming phytate?s adverse properties. Aim 3 strives to probe the phosphoryl transfer chemistry of phytate by exploring the use of polyamine-containing macrocycles as catalysts for phosphate hydrolysis and other phosphatase activity. X-ray crystallography and multi-nuclear, multi-dimensional NMR spectroscopy for both solid state and solution chemistry, respectively, are playing major roles in elucidating the physical and chemical properties of phytate in all three aims.