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PDBsum entry 3cfd
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Immune system
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PDB id
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3cfd
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References listed in PDB file
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Key reference
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Title
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Deeply inverted electron-Hole recombination in a luminescent antibody-Stilbene complex.
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Authors
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E.W.Debler,
G.F.Kaufmann,
M.M.Meijler,
A.Heine,
J.M.Mee,
G.Pljevaljcic,
A.J.Di bilio,
P.G.Schultz,
D.P.Millar,
K.D.Janda,
I.A.Wilson,
H.B.Gray,
R.A.Lerner.
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Ref.
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Science, 2008,
319,
1232-1235.
[DOI no: ]
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PubMed id
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Abstract
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The blue-emissive antibody EP2-19G2 that has been elicited against
trans-stilbene has unprecedented ability to produce bright luminescence and has
been used as a biosensor in various applications. We show that the prolonged
luminescence is not stilbene fluorescence. Instead, the emissive species is a
charge-transfer excited complex of an anionic stilbene and a cationic, parallel
pi-stacked tryptophan. Upon charge recombination, this complex generates
exceptionally bright blue light. Complex formation is enabled by a deeply
penetrating ligand-binding pocket, which in turn results from a noncanonical
interface between the two variable domains of the antibody.
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Figure 2.
Fig. 2. Electrostatic and shape complementarity of the hapten 1
in (A) the EP2-25C10 and (B) the EP2-19G2 antibody-combining
site. Slices through the center of the binding sites are shown.
The heavy and light chains are colored in blue and green,
respectively. The electrostatic potential was calculated in APBS
(30) and mapped onto the surface with the color code ranging
from –30 kT/e (bright red) to +30 kT/e (dark blue). Both
binding pockets are highly apolar, but strongly differ in their
depth and penetration of the variable antibody domain. (C)
Crystal structure of purple-fluorescent antibody EP2-25C10 in
complex with 1 (yellow). The 2F[o] – F[c] electron density map
around hapten 1 is contoured at 1.5  . (D) Crystal
structure of the blue-emissive antibody EP2-19G2 in complex with
1 (yellow) (4). Trp^H103 undergoes parallel  -stacking with 1 and
forms a charge-transfer complex in the excited state. In
contrast, stilbene 1 in EP2-25C10 does not engage in any -stacking
interactions with tryptophan.
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Figure 5.
Scheme 1.
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The above figures are
reprinted
by permission from the AAAs:
Science
(2008,
319,
1232-1235)
copyright 2008.
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