Biomedical Engineering Reference
In-Depth Information
However, the triple helix can partly reform for gelatin when the temperature of the
sample falls below the gelation temperature.[31] The triple helix of native collagen can
transform to the random coil configuration when it is heated above the denaturation
temperature. In the denaturation process, the physical properties such as viscosity, solubility
and optical activity changed due to the collapse of the triple helical structure. CD spectra and
viscosity change are widely used to determine the denaturation temperature of native
collagen. The helix-coil transition of collagen involves the breakage of hydrogen bonds
between the adjacent polypeptide chains of collagen molecules in the denaturation process.
The intact trimers ( ) of collagen turn into individual chains (α) or dimers (β) in the transition,
causing the decrease of viscosity at the same time.
At 40
o
C BSA contains 51 % of alpha helical structure. The mean helix content,
f
H
(in % )
for BSA calculated according to [26,27].
Figure 5. Antonov et al. “Structural investigation of the interaction between bovine serum albumin and
acid gelatin in water”.
The addition of gelatin to BSA solution at BSA/gelatin weight ratios ranging from 2.0 to
0.4 leads to significant increase in the negative band at 222 nm and significant increase in the
negative maximum at 209 nm as shown in Figure 5. Such a increase in the
222
values
corresponds to an increase in the content of alpha-helical structures.
3.3. Conformational Changes (Fluorescence Measurements)
Figure 6 shows a typical fluorescence spectrum for an aqueous BSA solution at the
excitation wavelengths (
exc
) = 250 nm, 270 nm and 290 nm and 40
o
C. The wavelength of
maximum emission (
max
) was about 339 nm, regardless of
exc
in the range 250-290 nm.
The presence of even small amount of gelatin in BSA solution leads to a visable leads to a
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