CHEMICAL MODIFICATION OF HORSERADISH-PEROXIDASE WITH ETHANOL METHOXYPOLYETHYLENE GLYCOL - SOLUBILITY IN ORGANIC-SOLVENTS, ACTIVITY, AND PROPERTIES

The oxidation of polyethylene glycol monomethyl ethers (MW 350, 1990, and 5000) by the Moffatt-Swern method to the corresponding aldehyde is described. These aldehydes are used to modify horseradish peroxidase (HRP) by a reductive amination. The modification of two to three ε-NH2 groups of the enzyme was observed. The isoelectric point of the native HRP (pI 8.8) was shifted to pI 5.5 on modification. The modified enzymes have an activity close to that of the native enzyme. Only the enzyme modified with the aldehyde MW 5000 (HRP 5000) was soluble and active in organic solvents like toluene, dioxane, and methylene chloride. In toluene, HRP 5000 was more sensitive to hydrogen peroxide inhibition than in buffer. At room temperature, it is more stable in toluene than in buffer. © 1991.