Abstract
It is known that cystatins have not only regulatory functions in cellular protein catabolism, but also other physiological functions against viral and/or bacterial infection. Recently we have fond cystatin in the human hair shaft. The activity of human hair cystatin in a water extract of pieces of it reached a plateau after 3-hour incubation. The activity of cystatin was compared among three different lengths of hair. The shorter the hair was cut, the more hair cystatin was extracted. Cystatin was more easily extracted by adding a water-soluble detergent. On the basis of these results, the loss of human hair cystatin from the hair shaft seemed to be affected by the condition of the hair surface and by the detergents in hair shampoo.
