Metabolomics and Metabonomics

Metabolism is the ensemble of chemical transformations carried out in living tissue (§10.2); operationally it is embodied in the matter and energy fluxes through organisms. Metabolomics is defined as the measurement of the amounts (concentrations) and locations of the all the metabolites in a cell, the metabolites being the small molecules ($M_r \lesssim 1000$; e.g., glucose, cAMP, GMP, glutamate, etc.) transformed in the process of metabolism (i.e., mostly the substrates and products of enzymes). The quantification of the amounts of expressed enzymes is, as we have seen, proteomics; metabolomics is essentially an extension of proteomics to the activities of the expressed enzymes, and it is of major interest to examine correlations between expression data and metabolite data.