changes in intensity size distributions. At the temperature 56.5
◦
C
all BSA molecules undergo to aggregation with the average radius
of particles 110 nm (BSA
TA
). At this temperature the average size
of particles doesn’t changes with the time at least in the conditions
of experiments (during a few hours). The absence of native BSA
molecules after their limited thermo aggregation at 56.5
◦
C was also
confirmed by precipitation of BSA
TA
at 50,000 × g for 2 h with subsequent determination the concentration of BSA in supernatant by the
measurement of absorption at 279 nm. At 58
◦
C the average radius
of particles increases up to 300 nm, and these particles becomes
sedimentate in a few hours Further increase the temperature leads
to the beginning of thermal denaturation and irreversible precipitation of BSA [37]. Therefore we consider heat-induced aggregation
of BSA at 56.5
◦
C as limited aggregation.
The intensity size distributions for BSA and BSA
TA
at pH 5.4,
40
◦
C (before beginning of thermo aggregation of BSA) and different
concentrations of the protein are presented in Fig. 2.
On the contrary to the native BSA, the average size of BSA
TA
and
the width of it’s the intensity size distribution function are sensitive
to the protein concentration. The average radius increases (from
84 nm to 110 nm) when the BSA
TA
concentration changes from
0.128 wt% to 0.25 wt%, and it reach 180 nm at the concentration
of 0.5 wt%. Since thermo aggregation of BSA at the concentrations
higher then 0.25 wt% leads to formation of polydisperse aggregates, all subsequent experiments with BSA
TA
were performed with
the 0.25 wt% solutions preheated at 56.5
◦
C for 10 min as it was