Evolution of Oxygen Isotopologues in Phosphate and Pyrophosphate during Enzyme-Catalyzed Isotopic Exchange Reactions

Spencer R. Moller, Yuriy Sakhno, Ludmilla Aristilde, Ruth E. Blake, Deb P. Jaisi*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Inorganic pyrophosphatase (PPase) is an enzyme that catalyzes the hydrolysis of the phosphoanhydride bond in pyrophosphate (PPi) to release inorganic phosphate (Pi) and simultaneously exchange oxygen isotopes between Piand water. Here, we quantified the exchange kinetics of oxygen isotopes between five Piisotopologues (P18O4, P18O316O, P18O216O2, P18O16O3, and P16O4) and water using Raman spectroscopy and 31P nuclear magnetic resonance (NMR) during the PPase-catalyzed 18O-16O isotope exchange reaction in Pi-water and PPi-water systems. At a high PPiconcentration (300 mM), hydrolysis of PPiby PPase was predominant, and only a small fraction of PPi(â 1%) took part in the reversible hydrolysis-condensation reaction (PPiâ " Pi), leading to the oxygen isotope exchange between Piand water. We demonstrated that Raman and NMR methods can be equally applied for monitoring the kinetics of the oxygen exchange between the Piisotopologue and water. It was found that the isotope exchange determined by the spectroscopic methods was detectable as low as 0.2% 18O abundance, but the reliability below 1% was much lower. Given that high P concentrations (≥1 mM) are required in these methods, environmental application of these methods is limited to rare high P conditions in engineered and agricultural environments.

Original languageEnglish (US)
Pages (from-to)1543-1551
Number of pages9
JournalACS Earth and Space Chemistry
Volume6
Issue number6
DOIs
StatePublished - Jun 16 2022

Keywords

  • NMR spectroscopy
  • O-O isotope exchange
  • Raman spectroscopy
  • isotope kinetics
  • pyrophosphatase (PPase)

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Atmospheric Science
  • Space and Planetary Science

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