Preparation of porous chitosan/GPTMS hybrid membrane and its application in affinity sorption for tyrosinase purification with Agaricus bisporus

In this study NaCl particles (porogen) and gamma-glycidoxypropyltrimethoxysilane (GPTMS) (cross-linking agent) were used to make chitosan-silica porous hybrid membranes. An optimal chitosan/GPTMS weight ratio 1: 1 was found to prepare a novel CSG 1.0 membrane. Both macropores (10.72-202.29 mu m) in the membrane matrix and micropores (0.008-0.01 mu m) in the skeleton of the macropores were observed on CSG1.0. Five compounds, histidine, glutamic acid, tyrosine, L-DOPA, and p-aminobenzoic acid were individually grafted onto CSG1.0. They are linked as ligands by genipin for affinity adsorption of tyrosinase from a crude Agaricus bisporus solution. This study indicates the p-aminobenzoic acid (ABA) grafted chitosan membrane (CSG-ABA) exhibited the best sorption capacity on tyrosinase. Only one band on SDS-PAGE gel was found from the eluted protein of CSG-ABA that identified the selective adsorption of CSG-ABA on tyrosinase. The behavior of tyrosinase sorption by CSG-ABA followed pseudo-first order kinetics. The sorption process was exothermal, and the sorption capacity decreased as the operation temperature increased. The negative value of the sorption Delta S degrees showed the tyrosinase sorption by CSG-ABA was enthalpic dominant. This study shows CSG1.0 membrane is suitable to be modified for bioproduct separation. (c) 2007 Elsevier B.V. All rights reserved.