Elution of S ' 100 Aa from hair fiber : New model for hair damage emphasizing the loss of S ' 100 Aa from cuticle

In hair fiber, a cysteine-rich calcium-binding S100A3 protein is segregated in the inner part of the cuticle and postulated to play an important role in the attachment o the adjacent cuticular scale. In this study, elution of S100A3 from hair fiber was examined under various conditions by means of immunoblot analyses. The exposure of hair fiber to permanent waving lotions resulted in recoveries of substantial amounts of S100A3 by elution. Ultraviolet-light radiation and perming also increased the elution of S100A3 even without reductant. The distal part of hair fiber eluted less S100A3, as compared to the proximal section, under reducing conditions. These results suggest hat S100A3 is eluted preferentially by daily washing and rinsing, especially from damaged hair. Given the presence of soluble S100A3 in the inner part of cuticle, we propose a new mechanism of hair damage in which the elution of S100A3 plays a major role.