Fig. 2. Views of the three VHHs superimposed on PPA with
the acarbose molecule bound (pink). The PPA surface is in gray,
and its visible catalytic residue Asp-300 is in red. The C trace of
the VHHs is orange, the three CDRs (1-3) are colored red, green,
and blue, respectively, and each VHH surface is transparent.
Inset, close-up view of the PPA active site with the inhibitory
AMD9 VHH bound. The saccharidic inhibitor acarbose has been
positioned in the active site according to the x-ray structure
as a probe of the saccharide position. Two residues of the VHH,
Tyr-52 and Arg-52a (CPK yellow and orange), clash with the
modeled acarbose (views made with SPOCK (33)).
The above figure is reprinted
by permission from the ASBMB:
J Biol Chem