Mid-Infrared Spectroscopic Measurement of Ionic Dissociative Materials in the Metabolic Pathway

Abstract

We determine the pH dependency of the mid-infrared spectra in aqueous solution of the organic dissociative materials in the metabolic pathway: saccharide phosphates (G6P, F6P), adenosine, and its phosphates (ATP, ADP, AMP). The series of molar absorbance spectra for these reagents were obtained in a pH range of about 2 to 11 with a Fourier transform infrared (FT-IR) spectrometer equipped with a horizontal diamond attenuated total reflection (ATR) sampling accessory. We also provide a method of infrared spectral extraction of ionic dissociative materials by performing a linear least-square fitting utilizing the formulas of ionic dissociation equilibrium shift, and we obtain the infrared spectrum of each ionic species of the dissociative materials: G6P⁻, G6P²⁻; F6P⁻, F6P²⁻; ATP²⁻, ATP³⁻, ATP⁴⁻; ADP⁻, ADP²⁻, ADP³⁻; AMP, AMP⁻, AMP²⁻; and adenosine⁺, adenosine⁰. The infrared spectral structure of each ionic species of the dissociative materials in the metabolic pathway are discussed. Additionally, the possibility for a quantification system of the concentrations of the organic dissociative materials in varying pH is suggested.