Isotope Tracer Analysis and Metabolic Flux Analysis

Conventional metabolomics measures changes in metabolite abundance to gain insights into altered metabolism which can also be useful as diagnostic and prognostic markers. However, how a change in metabolite abundance is linked to changes in metabolic precursors and products or rates of reaction is complex and not easily predicted from such measurements. Stable isotope labelled tracer compounds can be introduced into biochemical systems and their movement through the metabolic system used to gain insights into precursor and product relationships (Isotope Tracer Analysis/ITA) and rates of reaction (Metabolic Flux Analysis/MFA). ITA and MFA involve more sophisticated experimental design and data analysis but  utilise the same analytical methods used in conventional metabolomics. ¹³C MFA is commonly applied using ¹³C glucose and/or ¹³C glutamine for example. The isotope tracers can be uniformly labelled with 13C or only at specific carbon atoms providing flexibility over how  downstream metabolic products are eventually isotopically labelled. The ability to measure the rates of metabolite interconversion in biochemical pathways, and identify altered metabolic pathway utilisation, is of major importance and isotope tracer and flux analysis provide this capability. Both are powerful technique that can be integrated with conventional metabolomics to provide mechanistic insights into underlying metabolic changes and uncover new metabolic reactions and pathways.