Study of protein adsorption on indigo particles confirms the existence of enzyme-indigo interaction sites in cellulase molecules

Adsorption of several crude and purified cellulases (from Trichoderma reese i. Penicillium verruculosum and Chrysosporium lucknowense) on indigo partic les and Avicel cellulose was studied. Much higher amounts of protein were b ound to indigo than to cellulose under similar conditions. For different pu rified enzymes, the quantity of bound protein per mg of adsorbent (indigo o r cellulose) varied in the range of 57-111 and 0-62 mug mg(-1), respectivel y. However, in general, the enzyme adsorption on indigo was less specific t han the adsorption on cellulose. Three endoglucanases, having the highest i ndigo-binding ability, demonstrated the best washing performance in the pro cess of enzymatic denim treatment. These data confirmed our previous findin gs that certain cellulases, which have indigo-binding sites (clusters of cl osely located aromatic and other non-polar residues) on the surface of thei r molecules, may remove indigo from the denim fabric better than cellulases with lower content of hydrophobic residues exposed to solvent. (C) 2001 El sevier Science B.V. All rights reserved.