Extended Data Fig. 9: ¹H NMR spectra of purified QS-21-Xyl from engineered yeast YL-46 compared to that of the QS-21 standard.

a, Full spectral comparison between the QS-21 extracted and purified from engineered yeast YL-46 (top, red) and a QS-21 standard (bottom, black) shows an overall match of all proton peaks. In particular, the peak at chemical shift 9.33 demonstrates the presence of the C23 aldehyde in the QS-21 made in engineered yeast. b, Expanded spectral comparison between the purified QS-21 from YL-46 (top, red) and a QS-21 standard (bottom, black). The well-matched anomeric proton peaks confirm the correct connectivity between the sugar moieties. The absence of apiose proton peaks, highlighted in orange, in the yeast sample further confirms the production of QS-21-Xyl exclusively, owing to the specificity of the GT. Both spectra were recorded in acetonitrile-d₃:D₂O 1:1, 500 MHz.