Intermolecular interactions of reduced nicotinamide adenine dinucleotide (NADH) in solution

POSTER

Abstract

Nicotinamide adenine dinucleotide (NAD$^{+}$/NADH) is a coenzyme involved in cellular respiration as an electron transporter. In aqueous solution, the molecule exhibits a folding transition characterized by the stacking of its aromatic moieties. A transition to an unfolded conformation is possible using chemical denaturants like methanol. Because the reduced NADH form is fluorescent, the folding transition can be monitored using fluorescence spectroscopy, e.g., via a blue-shift in the UV-excited emission peak upon methanol unfolding. Here we present evidence of interactions between NADH molecules in solution. We measure the excited-state emission from NADH at various concentrations (1-100 $\mu $M in MOPS buffer, pH 7.5; 337-nm wavelength excitation). Unlike for the folded form, the emission peak wavelength of the unfolded form is concentration dependent, exhibiting a red-shift with higher NADH concentration, suggesting the presence of intermolecular interactions. An understanding of NADH spectra in solution would assist in interpreting intercellular NADH measurements used for the \textit{in vivo} monitoring cellular energy metabolism.

Authors

  • Doug Petkie

    AFRL/RX, AFRL/RX, Systran Systems Inc, UCSD, Los Alamos National Laboratory, Ohio Northern University, BFS, Germany, Florida State University, Monmouth College, Ohio Wesleyan University, Department of Chemical and Biomolecular Engineering, The University of Akron, Physics Department, John Carroll University, Department of Chemistry, Knight Chemical Laboratories, The University of Akron, Australian National University, Miami University, Oxford, OH, University of Cincinnati, University of Findlay, Naval Research Laboratory, Washington, DC 20375, Cleveland State University, Health Sciences Dept, Cleveland State University, Physics Dept, Cleveland State University, Bucknell University, Wright State University, Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB, Wright State University, Department of Physics, University of Puerto Rico, Department of Mechanical Engineer, Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB and UES, Inc., Department of Environmental Science and Policy, School of Science, Marist College, Poughkeepsie, NY 12601, USA, AFRL/711 HPW, EPA Sustainable Technology Division, University of Akron, Rose-Hulman Institute of Technology, Harvard University, LSU, Ohio University, Wittenberg University, Student

  • Doug Petkie

    AFRL/RX, AFRL/RX, Systran Systems Inc, UCSD, Los Alamos National Laboratory, Ohio Northern University, BFS, Germany, Florida State University, Monmouth College, Ohio Wesleyan University, Department of Chemical and Biomolecular Engineering, The University of Akron, Physics Department, John Carroll University, Department of Chemistry, Knight Chemical Laboratories, The University of Akron, Australian National University, Miami University, Oxford, OH, University of Cincinnati, University of Findlay, Naval Research Laboratory, Washington, DC 20375, Cleveland State University, Health Sciences Dept, Cleveland State University, Physics Dept, Cleveland State University, Bucknell University, Wright State University, Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB, Wright State University, Department of Physics, University of Puerto Rico, Department of Mechanical Engineer, Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB and UES, Inc., Department of Environmental Science and Policy, School of Science, Marist College, Poughkeepsie, NY 12601, USA, AFRL/711 HPW, EPA Sustainable Technology Division, University of Akron, Rose-Hulman Institute of Technology, Harvard University, LSU, Ohio University, Wittenberg University, Student

  • Paul Urayama

    Miami University