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Figure 2.
FIG. 2. Comparison of the carbohydrate binding pockets in
MVL free and complexed to Man[3]GlcNAc[2]. The backbone of the
binding pocket and side chains involved in protein-carbohydrate
hydrogen-bonding interactions is displayed, and each panel shows
a best-fit superposition of the eight MVL monomers in the
asymmetric unit in the free and bound states. A, N-domain; B,
C-domain. Free MVL, red; complexed MVL, blue; Man[3]GlcNAc[2]
(one of the eight molecules bound to each domain), yellow, with
oxygen atoms in red and nitrogen atoms in blue. Note that the
O-6 hydroxyl group of the Man4 unit is hydrogen-bonded to the
hydroxyl group of Thr-38 in the N-domain pocket (A); in the
C-domain pocket (B) the equivalent residue is Arg-97, and hence
no such hydrogen bond can be formed. This difference leads to a
180° rotation about the O-5-C-5-C-6-O-6 dihedral angle of
Man4 such that the C-6-O-6 bond points in the opposite direction
in the N- and C-domain pockets.
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