STRUCTURAL INVESTIGATION OF THE INTERACTION BETWEEN BOVINE SERUM ALBUMIN AND ACID GELATIN IN WATER - Biochemistry and Biotechnology: Research and Development - page 72

thermoaggregation process is observed in a narrow temperature range, and the absorbtion
values becomes very high already at 60 o C. The degree of reversibility of thermoaggregation
depends on the final temperature of heating and the time required for the temperature cycles
[20]. An increase of the residence time at the higher temperatures increases the degree of
irreversibility.
For sufficiently rapid heating-cooling processes (1 o C per minute and higher) and final
temperatures, which are not too high, the extent of aggregation remains insignificant and the
absorbtion reaches its initial value after cooling; the process can thus be considered to be
reversible. For BSA concentration 1% wt the upper temperature limit amounts to 55 o C. The
present of even small amount of gelatin in BSA solution (For q = 4 (q=BSA/gelatin w/w) the
critical aggregation temperatures increase significantly as shown in Figure 7. It can be seen
from this graph that the critical aggregation temperatures increase monotonically from 55 o C
to 58 o C when the concentration of gelatin in mixture increases (when q decrease from 4 to
0.4).
In order to quantify the effect of gelatin on aggregation of BSA, we have performed DLS
experiments for solutions of BSA, and the their mixture with gelatin at q =1.
Figure 8. Antonov et al. “Structural investigation of the interaction between bovine serum albumin and
acid gelatin in water”.
At these conditions the most of BSA molecules interacts with gelatin molecules (Figure
2) The scattering intensity as a function of size and the volume fraction as a function of size
for 0.25 wt% BSA is shown in Figure 8. One can see the thermoaggregation of BSA takes
places starting from 54 o C and at 56 o C almost all BSA molecules form a large (> 200 nm in
size) thermoaggregates. The thermal behavior of the BSA/gelatin mixture is differ from that
of BSA solution (Figure 9). In this case thermoaggregation process start the only at 58 o C, but
even at this temperature the only small part of BSA molecules form a large aggregates (Fig 9
b). The results demonstrate that the presence of gelatin increase considerably stability of BSA
molecules against thermoaggregation.