A first order experimental design to assess soluble proteins released by a new keratinase from Doratomyces microsporus on human substrates.

The influence of temperature, pH, keratinase concentration, substrate concentration and incubation time on the soluble proteins released by a new keratinase from Doratomyces microsporus was studied with an experimental design assisted by a simplex method. Only 16 spectrophotometric analyses were required. This study was carried out by measuring, according to Smith's method, the concentration of soluble proteins released by the enzyme on two human substrates: stratum corneum and nails. Results give optimum conditions for the keratinase to release the soluble proteins: Temperature, 28 degrees C; pH, 9.5; keratinase concentration, 0.94% (weight of keratinase lyophilisat/final volume), substrate concentration, 4.9% (weight of skin powder/final volume); and a 5 h 50 min incubation for the stratum corneum. Temperature, 37 degrees C; pH, 9.2, keratinase concentration, 0.11% (weight of keratinase lyophilisat/final volume); substrate concentration, 4.9% (weight of nail powder/final volume) and a 6 h 10 min incubation time for nails.