Online Oxygen Kinetic Isotope Effects Using Membrane Inlet Mass Spectrometry Can Differentiate between Oxidases for Mechanistic Studies and Calculation of Their Contributions to Oxygen Consumption in Whole Tissues

作者：Cheah Mun Hon^*; Millar A Harvey; Myers Ruth C; Day David A; Roth Justine; Hillier Warwick; Badger Murray R

来源：Analytical Chemistry, 2014, 86(10): 5171-5178.

DOI：10.1021/ac501086n

The reduction chemistry of molecular oxygen underpins the energy metabolism of multicellular organisms, liberating free energy needed to catalyze a plethora of enzymatic reactions. Measuring the isotope signatures of O-16 and O-18 during O-2 reduction can provide insights into both kinetic and equilibrium isotope effects. However, current methods to measure O-2 isotope signatures are time-consuming and disruptive. This paper describes the application of membrane inlet mass spectrometry to determine the oxygen isotope discrimination of a range of O-2-consuming reactions, providing a rapid and convenient method for determining these values. A survey of oxygenase and oxidase reactions provides new insights into previously uncharacterized amino acid oxidase enzymes. Liquid and gas phase measurements show the ease of assays using this approach for purified enzymes, biological extracts and intact tissues.

• 出版日期2014-5-20