Fig. 3.

Pulsed EPR studies of T4L mutants bearing either two K1 side chains (black), a K1 and an R1 side chain (red), or two R1 side chains (green). (A) Background subtracted dipolar evolution. (B) Area-normalized distance probability distribution from Tikhonov regularization of the data in A. (C and D) Projection contours of the nitroxide spin locations of R1 and K1 calculated from the nine measured distance distributions in B. Probable locations of the nitroxide spins are shown as a gradient from red to yellow and overlaid on a ribbon model of T4L from the crystal structure (PDB ID code 150L, chain C) (46).