Fig. 2. ¹³C DNP NMR spectra of Gly*, Glc* supplemented K7M2 ECM. (A) ¹³C CP-MAS; nucleotide base signals assigned by 2D experiments and database shift values (ESI Schemes S1 and S2†) are labelled; (B) high frequency region of INADEQUATE J-transmitted SQ-DQ correlation spectrum (265 ppm ¹³C DQ sweep width to avoid aliasing; ^#, * – correlations between lipid olefinic carbons); (C) low frequency region of the same spectrum tracing out correlations within ribose (Rib), and deoxyribose (dRib), rings; (D) high frequency region of the ¹³C–¹³C DARR correlation spectrum base; (E) ¹⁵N DNP NMR of Gly*Glc* K7M2 ECM compared with that of labelled bone, supporting the assignment of the 235 ppm signal as purine N₇; (F) ¹³C{¹⁵N} TEDOR spectrum showing the expected purine N₇–C₅ and N₇–C₄, as well as the putative purine ring N₇–C₈, through-space correlations (¹⁵N sweep width 438 ppm to cover full ¹⁵N range).