1987 年 21 巻 2 号 p. 146-155
The sorption of keratin hydrolysate, as an inter-molecular cystine rich polypepetide, to hair and the cosmetic effect have been studied.
The amount of keratin hydrolysate sorbed to hair was determined by a novel method: the determination of the amount of sulfhydryl residues (R-SH) in keratin hydrolysate produced by the chemical interaction between cysteine residues (R-SH) in hair being reduced and cystine residues (R-S-S-R) in keratin hydrolysate. A large amount of R-SH was produced in keratin hydrolysate when reduced hair was immersed in the medium of the buffer solutions containing keratin hydrolysate, whease only a trace amount of R-SH in the control buffer was found when keratin hydrolysate was not present. The chemical alternation of hair was examined by the fluorescent microscopic observation of R-SH after labelled with N-(7-dimethylamino-4-methyl-coumarinyl)-maleimide (DACM). Intensive fluorescence was observed on the reduced hair, whease reduction of fluorescent intensity was observed on the keratin hydrolysate treated hair. The result showed a decrease of R-SH in the reduced hair. The decrease of cystine residues of the permed hair was also found by amino acid analysis, when the hair was treated with keratin hydrolysate after reduction in the permanent waving process. As the cosmetic application of keratin hydrolysate, the effect of keratin hydrolysate on the bleached and permed hair was demonstrated in the process of permanent waving as the waving efficiency.
These results implies that the sorption of cystine-rich keratin hydrolysate to the reduced hair was due to SH/SS interchange reaction between the hair and the keratin hydrolysate. It was also suggested that the effectiveness of keratin hydrolysate on the waving efficiency was based on the increase of hair elasticity due to the newly formed covalent bonds between the hair and the keratin hydrolysate.