Figure 2.

(a) Two-dimensional ¹³C–¹³C 20 ms PDSD of M2_18–60 H57Y ILFY (CP contact time 1.5 ms and 83 kHz TPPM decoupling) and (b) 2D ¹³C–¹⁵N 3.2 ms ZF-TEDOR of M2_18–60 H57Y ILFY both acquired at ω_r/2π = 12.5 kHz 700 MHz ¹H frequency, pH 7.5, and −6 °C. (c–e) Strips showing aromatic regions of the ZF-TEDOR. This data shows peak doubling indicative of dimer of dimer structure, even after protonation has partially occurred.