INCREASED THERMAL AND SOLVENT TOLERANCE OF ACETYLATED HORSERADISH-PEROXIDASE

Thermal stability of horseradish peroxidase (HRP) has been enhanced by acetylation with acetic acid N-hydroxysuccinimide ester (AA-NHS) unde r mild conditions. The half-life at 65 degrees C was increased fivefol d. This modification has also resulted in greater tolerance of the wat er-miscible organic solvents, dimethylformamide and tetrahydrofuran, a t 25 degrees C and 60 degrees C and of methanol at 60 degrees C. Analy sis of the free amino groups of HRP indicates that AA-NHS alters 3 of the HRP 6 lysine residues. This stabilization has been achieved by a s imple chemical modification involving neither immobilization nor the u se of cross-linking agents.