Figure 3.

Dante-selected C{F} (left) and C{P} (right) REDOR of the cell-wall sample of Figure 1. The Dante differencing of Figure 2 preceded REDOR dephasing. Four data blocks were collected resulting in spectra with and without Dante irradiation, each with and without ¹⁹F (or ³¹P) dephasing. The Dante differences (ΔS) are shown at the bottom of the figure and are the reference spectra for REDOR dephasing (ΔΔS) shown above. The terminal carboxyl of the d-alanyl label (178 ppm) has a much larger C{P} REDOR difference than does the peptide d-alanyl label (175 ppm), indicating preferred proximity of un-cross-linked d-alanyl units to wall teichoic acid.