Phosphorus K beta X ray emission spectroscopy detects non covalent interactions of phosphate biomolecules in situ

Phosphorus is ubiquitous in biochemistry, being found in the phosphate groups of nucleic acids and the energy transferring system of adenine nucleotides e.g. ATP . K amp; 946; X ray emission spectroscopy XES of phosphorus has been largely unexplored, with no previous applications to biomolecules. Here, the potential of P K amp; 946; XES to study phosphate containing biomolecules, including ATP and NADPH, is evaluated, as is the application of the technique to aqueous solution samples. P K amp; 946; spectra offer a detailed picture of phosphate valence electronic structure, reporting on subtle non covalent effects, such as hydrogen bonding and ionic interactions, that are key to enzymatic catalysis. Spectral features are interpreted using density functional theory DFT calculations, and potential applications to the study of biological energy conversion are highlighte