ИСТИНА

Disulfide bonds are essential for hair protein structure and regeneration, being abundant in high molecular weight keratins and low-molecular keratin-associated proteins. They are formed in keratinization zone of hair follicle and further can be photomodified by UV -irradiation, generating thiols among other products. However, very little is known about hair topography of SH-groups. Terminal 10-cm-long grey hair shafts of two volunteers were cut into proximal (0.3-2 cm from hair root) and distal (8-10 cm from root) segments. Thiol content in soluble proteins was assessed in the segments of 40 hairs by Ellman’s method, and 12 hairs were analyzed by Raman microspectroscopy. According to integral Raman intensities of peripheral (underlying hair cuticle) and central (close to medulla) regions of transverse hair cuts, thiol content in proximal segments was slightly higher (by 0.4%) than in the distal ones, in both regions (p<0.05). Thiols in soluble proteins also declined from the proximal to distal segments (from 0.78 ± 0.08 to 0.48 ± 0.06 μg/g, p<0.05). Intensity of SS-bonds in the central regions grew from the hair roots to tips by 6% while in the peripheral region it decreased by 2.5%. The pronounced reduction in thiol content registered in the low-molecular soluble proteins of distal hair segments could be caused by their partial loss, presumably due to regular aqueous extraction. The increase in SS-bonds in the central region may result from the reactions of thiol exchange in the hair shaft.