New method for covalent immobilization of proteins to cellulose and cellulose derivatives

Cellulose and microcrystalline cellulose are treated consecutively with sodium periodate and urea. The interaction of urea derivatives with formaldehyde results in highly reactive groups, capable of further condensation with the amino acid residues of the proteins. The condensation of chymotrypsin, pepsin, and ovomucoid with such activated matrices has been studied in the pH interval 2 to 10. Differences have been found in the binding properties of basic and acid proteins. Satisfactory values have been obtained concerning the relative enzymatic and inhibitory activity of the immobilized products with respect to high- and low-molecular substrates. Chymotrypsin, immobilized on microcrystalline cellulose matrix, is found to manifest better catalytic properties compared with chymotrypsin immobilized on cellulose matrix. A probable sequence of the stages of chemical activation of the matrices and covalent binding of the proteins to them has been proposed. The main advantages of the proposed method consist of the high reactivity of the binding group in a wide pH range, its suitable length, and its easy synthesis.