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Figure 3.
FIG. 3. OPPs active site structure and reaction mechanism.
In A, the surface of active site is color coded from red to blue
according to charge potential from -15 to 15 k[B]T. This figure
was generated using GRASP (30). In B, two sulfate ions in the
active site of totally six sulfates of OPPs F132A mutant are
shown (these sulfate ions are more obvious than other data
sets). Along with two sulfate ions, amino acids Lys-41, Arg-44,
His-74, Asp-81, Asp-82, Asp-85, Arg-90, Arg-91, Asp-204,
Asp-205, and Asp-208 are shown in ball-and-stick model. S1
containing the first DDXXD motif is responsible for binding with
FPP, and S2 located downstream the FPP binding site functions to
stabilize the PP[i] leaving group. This is illustrated in C that
Arg-90 and Arg-91 are important in FPP binding, and AArg-44,
Lys-41, and His-74 surround another sulfate ion to grasp the
leaving group of FPP while reaction occurs.
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