Figure 1.

Compound similarities in common metabolite databases. (a) Cumulative percentage of isobaric metabolites extracted from the KEGG-database. “All” denotes organic metabolites with associated enzymatic reaction, “human” a subset with associated pathways in humans, “exact masses” indicate the exact mass as contained in the database, while “unit resolution” counts the frequencies with rounded masses. (b) Cumulative proportion of isobaric metabolites extracted from the human metabolome database (HMDB). “All” denotes non-lipid metabolites in the HMDB, while “human” denotes metabolites listed as “detected” or “quantified”. (c) Distribution of shared masses over the mass-range. Isomers were counted on the respective human dataset for exact mass. Each line represents a 5 $\mathrm{Da}$ mass window, with the maximum of the counts within the window indicated by colour.