Unexpected similarities between the Schizosaccharomyces and human blood metabolomes, and novel human metabolites (Blood fraction)

Metabolomics, a new branch of chemical biology, provides compositional and quantitative information about the state of organism or cell at the levels of metabolite constituents. We here report non-targeted metabolome of human blood that is made up of plasma and red blood cells (RBCs), using liquid-chromatography and mass spectrometry (LC-MS). Previously, metabolome of a microbe, the fission yeast Schizosaccharomyces pombe, was reported. Two sets of metabolome results are highly similar in their compositions: among 133 compounds identified in human blood, 101 (75%) are also present in S. pombe, and among 57 compounds enriched in RBC, 45 (78%) are also present in S. pombe. Most abundant metabolites are ATP, glutathione and glutamine. Many of other relatively abundant metabolites identified are also implicated in energy, anti-oxidant and amino acid metabolism. We show fourteen newly-identified blood compounds; citramalate, GDP-glucose, trimethyl-histidine, trimethyl-phenylalanine, trimethyl-tryptophan, trimethyl-tyrosine, UDP-acetyl-glucosamine, UDP-glucuronate, dimethyl-lysine, glutamate methyl ester, N-acetyl-(iso)leucine, N-acetyl-glutamate, N2-acetyl-lysine, and N6-acetyl-lysine (the first eight are enriched in RBC). Ten of them are also detected in S. pombe, and ten of them are methylated or acetylated, amino acids. Trimethylated or acetylated free amino acids are also abundant in white blood cell. Their physiologic role may be investigated in the future by yeast genetics.