Deuterium Oxide Labeling for Global Omics Relative Quantification (DOLGOReQ): Application to Glycomics

A new
relative quantification strategy for glycomics, named deuterium
oxide (D2O) labeling for global omics relative quantification
(DOLGOReQ), has been developed based on the partial metabolic D2O labeling, which induces a subtle change in the isotopic
distribution of glycan ions. The relative abundance of unlabeled to
D-labeled glycans was extracted from the overlapped isotopic envelope
obtained from a mixture containing equal amounts of unlabeled and
D-labeled glycans. The glycan quantification accuracy of DOLGOReQ
was examined with mixtures of unlabeled and D-labeled HeLa glycans
combined in varying ratios according to the number of cells present
in the samples. The relative quantification of the glycans mixed in
an equimolar ratio revealed that 92.4 and 97.8% of the DOLGOReQ results
were within a 1.5- and 2-fold range of the predicted mixing ratio,
respectively. Furthermore, the dynamic quantification range of DOLGOReQ
was investigated with unlabeled and D-labeled HeLa glycans mixed in
different ratios from 20:1 to 1:20. A good correlation (Pearson’s r > 0.90) between the expected and measured quantification
ratios over 2 orders of magnitude was observed for 87% of the quantified
glycans. DOLGOReQ was also applied in the measurement of quantitative
HeLa cell glycan changes that occur under normoxic and hypoxic conditions.
Given that metabolic D2O labeling can incorporate D into
all types of glycans, DOLGOReQ has the potential as a universal quantification
platform for large-scale comparative glycomic experiments.