Chemistry Reference
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two separate locations, unlike the previous single-point attachment conjugate. The
Mn(III)(salen) derivative was modeled into myoglobin to identify two positions that
would yield the best fit into the heme pocket (Figure 5.17). In addition to an increase
in the rate of sulfoxidation of the substrate thioanisole, the enantioselectivity increased
to 51% ee. These results indicate that the dual anchoring strategy may be applied to the
design of other artificial metalloenzymes to obtain better enantioselective control. It
may also be possible in future work to modulate substrate specificity as well.
5.5
Antibodies as Scaffolds for Catalyst Design
5.5.1
Antibodies as Specificity Elements
The immune system of higher eukaryotes produces antibody molecules that recognize
a broad range of small molecules. By immunizing animals with specific antigens, pro-
duced by conjugating organic compounds to carrier proteins, antibodies that specifi-
cally recognize the original small molecule can be generated. This allows protein scaf-
Figure 5.18 Stereo view of the structure of the antibody MOPC 315
complexed with an amide-containing hapten. Only the region near the
hapten binding site is shown. The hapten and Y
34
are shown as larger
sticks with the remaining residues in the binding site as smaller sticks.
Residues shown include Y
34
,W
93
and W
98
(from V
L
) and W
333
,H
335
,Y
339
,
R
350
,K
359
,Y
399
,Y
401
and S
405
(V
H
). Color scheme: Carbon (white), oxygen
(red) and nitrogen (blue).
