Figure 4.
Fig. 4. Electron density for the cross-linker. Shown is
the simulated annealing F[o] F[c] omit
map for the electron density of p-PDM together with the
cross-linker modeled into the structure of S1-ADP-p-PDM. To
generate this map, contoured at the 3.0 level,
residues C693 and K705 were omitted along with the p-PDM model.
The SH1 helix is disordered, including the SH1 sulfhydryl
(C703). Biochemical studies with rabbit muscle myosin have
indicated that this thiol can be cross-linked to the SH2
sulfhydryl (C693) by p-PDM (15, 24, 25). However, this map
reveals that, in scallop S1, p-PDM cross-links the SH2
sulfhydryl to the side chain of K705, instead of SH1. The
scallop S1-ATP[ -S]-p-PDM
structure gives the same result.
F[c] omit
map for the electron density of p-PDM together with the
cross-linker modeled into the structure of S1-ADP-p-PDM. To
generate this map, contoured at the 3.0 
level,
residues C693 and K705 were omitted along with the p-PDM model.
The SH1 helix is disordered, including the SH1 sulfhydryl
(C703). Biochemical studies with rabbit muscle myosin have
indicated that this thiol can be cross-linked to the SH2
sulfhydryl (C693) by p-PDM (15, 24, 25). However, this map
reveals that, in scallop S1, p-PDM cross-links the SH2
sulfhydryl to the side chain of K705, instead of SH1. The
scallop S1-ATP[ 
-S]-p-PDM
structure gives the same result.