Proteolytic enzymes Proteolytic enzymes do not readily attack fibroin in fibrous form apparently because the protein chains in silk are densely packed without bulky side chains. Serious degradation may be caused by water or steam at 100 C. 10. Oxidation Reports regarding the oxidation of proteins are rather meagre since the reactions are very complex. Hydrogen peroxide is absorbed by silk and is thought to form complexes with amino acid groups and peptide bonds. It has been demonstrated that hydrogen peroxide diminishes the tyrosine content and further that the peptide bonds are broken at the tryosine residues.
Peracetic acid causes more rapid scission and produces more acid groups than peroxide.
Other agents Chlorine attacks fibroin more vigorously than does sodium hypochlorite. The oxidation is mainly at the tyrosine residues.