Figure 1.

PDSD spectra of M2 acquired under four sample conditions show that chemical shifts are unperturbed by 60% glycerol if glycerol is the last component added to the sample. In a) and b) are shown cross peaks of G34 and H37, respectively in uniformly ¹³C labeled samples. The first three panels were recorded using a 700 MHz instrument with a Varian 3.2 mm triple channel probe spinning at 12.5 kHz. The fourth panel (4× Rmt then 60% glycerol) was recorded at 750 MHz with a triple channel Bruker e-free probe spinning at 13.4 kHz. These spectra of the D21G and D24G double mutant were recorded at ~278 K using 15 ms of mixing. Peaks of G34 and H37 are displayed because of the excellent resolution in these regions of the spectrum, and a clear change in frequency upon drug binding. Peaks other than those from G34 and H37 are indicated with an asterisk.