Accurate Determination of Isotopic Abundance of Intracellular Metabolites of Saccharopolysporaerythraea Based on Ultra Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry

Abstract

Abstract A method was established for measuring 13C isotopic abundance of intracellular metabolites of Saccharopolysporaerythraea by ultra-high performance liquid chromatography (UPLC)-triple quadrupole mass spectrometry. Under the optimized chromatographic conditions of UPLC, and the appropriate and unique tube lens voltage, collision energy and ion pair, one-to-one method, one-to-many method and SIM method were established for measuring 13C isotopic abundance based on the length of the parent and daughter ions carbon chains and whether the daughter ions contain 13C atoms. The three methods were then applied to measure naturally labeled intracellular metabolite standards and 13C labeled samples. According to the gap between the experimental value and the theoretical value, the best method was found for each metabolite of different characteristics. The results showed that one-to-one method was the most effective for measuring the metabolites of daughter ions not containing 13C atoms represented by sugar phosphates, one-to-many method was the best for measuring the metabolites of both parent and daughter ions containing 13C short carbon chains represented by carboxylic acids, SIM method could played a role in measuring the metabolites of both parent and daughter ions containing 13C long carbon chains represented by coenzyme A. These methods had a good measurement precision and could be applied to the measurement of Saccharopolysporaerythraea intracellular metabolites, which would contribute to consequent study of the metabolic mechanism and the efficient expression of erythromycin.