To collect various protein fractions, we followed a previously described approach [20] based on mild protein elution (to prepare EP) and mechanical homogenization (to prepare SP and SPe) of hair samples in a carbonate buffer solution (pH 10.5). This approach was applied to both UV irradiated and non irradiated hair of each subject as described in Section 2.
The first raw indicates if the proteins were eluted from hair before homogenization. UV irradiation significantly increased the quantity of EP (Table 1). The same effect was shown for SP and SPe even if it was less pronounced these fractions it was less pro- nounced than for EP: increase by 20–35% (SP and SPe correspond- ingly) vs 140% (in case of EP). Protein concentration was determined by absorption at 240 nm. In SPe samples protein con- centration was also measured by the biuret method which showed the same result – increase by 23%.
So, if UV irradiation of hair increased the quantity of soluble proteins within the fibers, some of these modified peptides were