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propensity is inherent of the hexapeptide-repeating structure of the
central domain of silk moth chorion proteins. This is further supp-
orted by the fact that peptide-analogues of the B family of silk moth
chorion proteins also fold and self-assemble forming amyloid-like
fibrils.
17
Thus, it appears that the amyloidogenic propensity in the
case of silkmoth chorion proteins is hidden into the hexapeptide
repeats of silkmoth chorion proteins, encoded after millions of
years of molecular evolution.
5
Further, it probably implies that the
underlying molecular substructure that dictates proper folding and
self-assembly of chorion fibrils into the superstructure of silkmoth
chorion is encoded into the tandem hexapeptide repeats present
in the amino acid sequences of the central domain of silkmoth
chorion proteins.
a
b
600
800
1000
1200
1400
1600
1800
Raman shift (cm -1
)
1
Figure 4.10
(a) FT
) spectrum of cA peptide
amyloid fibrils, cast on an Au mirror. The second derivative
spectrum is included. The positions of the amide I at
1668 cm
-
Raman (450-1800 cm
1
1
and amide III at 1233 cm
bands in the Raman
spectrum suggest a
-sheet secondary structure for the cA
peptide in the fibrils. 23 Error bar equals 0.5
β
ATR FT-IR
(900-1800 cm -1 ) spectrum of cA peptide amyloid fibrils,
cast on an Au mirror. The second derivative spectrum is
included. The amide I and III bands at 1628 and 1234 cm
σ
. (b)
1
,
respectively, clearly indicate a
-sheet type of structure for the
cA peptide in the fibrils. The shoulder in the amide I region, at
1692 cm
β
1
-sheets are antiparallel. 18,24 Error
, suggests that the
β
bar equals
in the IR spectrum. Reprinted from Biopolymers
(Biospectroscopy),
σ
72,
185-192,
copyright
(2003),
with
permission from John Wiley and Sons.
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