Chemical modification of proteases for wool cuticle scale removal

Abstract

Over the last few decades several enzymatic processes to improve properties of wool fabrics like felting tendency, shrink resistance, dyeing ability and handling characteristics have been described. Previous investigations into the use of proteases to hydrolyse the cuticles at the surface of wool fibres, resulted in high strength and weight losses. Therefore restriction of the enzyme activity to the wool surface or control of enzyme diffusion to the cortex cells is required.To change the diffusion behaviour of proteases in wool fibres, the soluble polymer PEG was covalently attached to a protease from Bacillus lentus. Modified enzymes with different molecular weights were compared. These modified enzymes retained up to 80% of their activity in the standard assay while hydrolysis of wool fibres was successfully restricted to cuticles, resulting in a 90% decrease in weight losses compared to non-modified enzymes.