Dissolution of proteins from hair (I)

Abstract

It has been reported that hair was affected by shampooing and chemical treatment. However, no other detailed study on dissolved proteins and amino acids from damaged hair has been reported. The purpose of the present study was to analyze dissolved proteins and amino acids from hair after bleaching.Untreated woman's hair was washed and treated with bleaching agent. Bleached hair was soaked in various solutions such as distilled water, acetic acid, ammonia, and SLS 1.0% aqueous solution. Dissolved proteins and amino acids were analyzed by fluorometric amino acid analyzer after acid hydrolysis.The amount of dissolved proteins from bleached hair was more than untreated one, and these amino acid compositions were different. Among amino acids, cysteic acid dissolved from bleached hair was markedly different. Amounts of dissolved amino acids from bleached and untreated hair were much less than those of dissolved proteins. The higher pH of the soaking solution, the more dissolved proteins from hair and the hair damage amplified more significantly the effects of pH in bleached hair. However, amino acids composition of the dissolved proteins was not different among those soaking solutions. SLS was well known as a material of shampoo and the effect of SLS 1.0% aqueous solution on the amount and the amino acid composition of dissolved proteins was not different from water.In conclusion, the effect that bleaching has on hair could be demonstrated quantitatively by the analysis of dissolved proteins and amino acids from hair. From these results, it was suggested that this method might be one of the useful indicators of hair damage.