Comparison of two hard keratinous substrates submitted to the action of a keratinase using an experimental design

The influence of temperature, pH, keratinase concentration, substrate conce ntration and incubation time on the soluble proteins released by a new kera tinase from Doratomyces microsporus was studied with a second-order experim ental design. Only 15 or 18 spectrophotometric analyses were required to de termine the optimal experimental conditions for this keratinase on nail and hoof. This study was carried out by measuring, according to Smith's method , the concentration of soluble proteins released by the enzyme on two subst rates: nails and sheep hooves. Results give optimum conditions for the kera tinase to release the soluble proteins: pH 8.2, keratinase concentration 0. 14% (weight of keratinase lyophilisate/final volume) and substrate concentr ation 5% (weight of nail powder/final volume) for nails; temperature 38.8 d egreesC, pH 9, substrate concentration 5% (weight of hoof powder/final volu me) and a 5 h 55 min incubation time for hooves. (C) 2001 Elsevier Science B.V. All rights reserved.