Convenient procedures for human hair protein films and properties of alkaline phosphatase incorporated in the film

We have developed a novel method of extracting proteins from human hair in the absence of detergent called the 'Shindai Method'. Using the protein solution consisting of hard alpha-keratins and matrix proteins prepared by this method, we developed two procedures for preparing hair protein films. The protein solution was mixed with trichloroacetic acid (TCA), perchloric acid (PCA) or guanidine-HCl (GHA), and then exposed in distilled water. Light brown aggregates immediately formed (Pre-cast method). The other method is based on the same characteristics of the hair proteins to form protein aggregates. The protein was directly exposed to the solution containing TCA, PCA, GHA, HCl, H2SO4 or acetate buffer (Post-cast method). The maximum yield was greater than 70%. These protein films were water-insoluble and mainly made up of a-keratins. Scanning electron micrographs showed that the fine surface of the protein films was composed of particles, filaments, and porous structures and the constitution was dependent on the preparation procedure used. When porcine intestine alkaline phosphatase (ALP) was mixed with the hair protein solution in a Post-cast method using acetate buffer (pH 5), ALP was incorporated into the a-keratin films. The activity retained in the protein film was approximately 8% of the original level. The biochemical properties of the ALP activity in the film were similar to those of the native enzyme.