Preparation Of Catalytic Materials By Covalent Immobilisation Of Pepsin On Cotton Fibers Activated By Tosyl Chloride
A study was performed on the possibility of utilisation of hydrophilic cotton for the elaboration of enzymatic bio-catalytic materials. Pepsin was covalently bounded to the cotton matrix using tosyl chloride as activating agent and the stability of such pepsin modified materials was studied. The immobilized pepsin was the most stable at pH 1.5-2 as was the case of the soluble enzyme. Enzyme immobilization on the tosylated cotton followed a nucleophilic substitution mechanism as evidenced by UV and FTIR spectra and about 0.75 mg of pepsin per gram of cotton could be immobilized. However, the protein coupling efficiency was 38% (if 1 g of cotton is used). Enzyme activity was maintained to about 50% of its initial activity over one month. The continuous decrease of the activity of the immobilized pepsin was also accentuated by the successive formation followed by adsorption of the haemoglobin heme (solid particles) on the cotton fibers, which lowered the reaction between the enzyme active sites and the substrate. This study showed that proteases immobilized on cotton could be used as bioreactors. iÂÂ 2006 Trade Science Inc. - INDIA