Immobilization of cytochrome c on the cylindrical mesoporous silica extrudates

Siliceous and aluminum containing C12-MCM-41, C16-MCM-41 and SBA-15 mesoporous molecular sieves were synthesized in the powder (P) form by hydrothermal method. These materials were shaped into cylindrical extrudate (Ex) form by compounding with additives such as bentonite (binder), methyl cellulose and water. The adsorption of cytochrome c (cyt c) onto the extrudates of these mesoporous molecular sieves was studied at different solution pH. It was observed that maximum adsorption was found to be near the isoelectric point (pI) of the protein. The extrudates of SBA-15 showed a maximum amount of cyt c adsorption capacity and this may be due to the high pore volume and large pore diameter compared to other C12-MCM-41(Ex) and C16-MCM-41(Ex). Incorporation of aluminium in to the siliceous material showed maximum adsorption of cyt c compared to pure siliceous materials. The observed consequence may be due to the strong electrostatic interaction between the negative charges on the aluminium sites and positively charged amino acid residues of cyt c.