Amino acid compositions and sulfur content of dry keratin hydrolysate and its fractions obtained by membrane ultrafiltration were determined.
Remarkable differences were found in amino acid compositions and sulfur content between the fraction of molecular weight from 500 to 1, 000 and the other fractions.
The ferrous salt FeSO4 (NH4) 2SO4·6H2O (Mohr's salt) or ferric solution of Fe2 (SO4) 3xH2O was added at the same concentration to an aqueous keratin hydrolysed solution and its fractions.
The ultraviolet and visible absorption spectra of the hydrolysed protein solutions to which ferric solution had been added were the same as those to which the ferrous salt had been added, when concentrations of Fe (II) and Fe (III) were equal.
From the above results for absorption spectra and change in the colors of Fe (III) added hydrolysed protein solutions into which 1, 10-phenanthroline solution had been introduced, it is apparent the mercapto group (-SH) containing keratin hydrolysed proteins has reducing activity and can reduce Fe (III) to Fe (II) in hydrolysed protein solutions. Also, the keratin hydrolysate and its fractions were shown to be connected to Fe (II) in a water-soluble chelate configulation in a pH range from 7.0 to 7.5, 25°C.