Study On The Enzymatic Hydrolysis Of Silk Fibroin

On the basis of effect comparison on hydrolysis of silk fibroin by proteinases, elastase was selected as the most effective enzyme to be studied in detail. With the methods of ninhydrin colorimetry and SDS-PAGE gel electrophoresis. the effects of influencing parameters, including temperature, pH value, enzyme dose, substrate concentration, and hydrolytic time were investigated. Results indicate some hydrolytic characteristics, the optimum temperature and pH value is 45 0C, 8.5 respectively, kinetic value Km is 4.3mg/mi. Moreover, the composition and structure of hydroiysates were determined by amino acid analysis, infrared spectrum, thermal analysis and X-ray diffraction. Results show that precipitate part (Cp) only possesses a low ratio, and fB -sheet is the main conformation, with the compact structure of crystal; the solution part(Cs), however, is the random-coil conformation as regenerated fibroin solution Meanwhile, the individual amino-acid content of Cp and Cs differs greatly. Gly, Ala and Ser amino acids occur mostly in Cp part by percentage of 90% on quantity, Tyr and Phe amino acids, however, rise to 15% in amount in Cs pail.