Table 1.

DNP enhancements for different samples. All samples were comprised of 5.5/2.7/2/1 DPPC-d₆₂/DPPC/POPG/cholesterol lipids reconstituted in UB, pH 7.4, containing 10 mM AMUPol and 10% DMSO. Peptide-containing samples incorporated KL₄ with a single ¹³C isotope at the carbonyl carbon for specific amino acid positions. Site-specific ¹³C-labelled KL₄ peptides at residues L12 or L12, L13 were synthesized and peptides were reconstituted at 2 mol% relative to the lipids. Enhancement values are reported with ±10% accuracy due to limited SNR for microwaves off spectra.

Sample	Buffer	Lipid Glycerol	Lipid C=O	Lipid CH2	Lipid C=C	Peptide C=O
KL4/Lipids-1	36	22	13	13	14	13
KL4/Lipids-2	23	15	8	8	N.D.	8
Lipids only	34	58	48	45	34	--