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Figure 3.
Active site with the acarbose covalent intermediate. A, the
acarbose intermediate covalently bound to Asp^363 shows tight
interactions with the residues at subsite -1 in the dimer. The
inhibitory acarviosine moiety is bound to subsites -2 and -3.
The catalytic residues (Asp^363, Glu^399, and Asp^471) and other
conserved residues in the active site are indicated by sticks.
The ligand molecules are shown in yellow. Helix α4 unique to
TreX is in pink. B, the electron density map of 2F[o] - F[c]
(1.0 σ) shows the acarbose intermediate molecule at subsites
-1, -2, and -3 (left) and the glucose molecules at subsites +2
and +3 (right). C, the omit map of F[o] - F[c] drawn without the
ligand shows the covalent binding of the acarbose intermediate
to Asp^326, contoured at 3.0 σ (left) and 5.0 σ (right).
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