HORSERADISH-PEROXIDASE EXTRACTION AND PURIFICATION BY AQUEOUS 2-PHASEPARTITION

The effect of poly(ethyleneglycol) (PEG) molecular weight, system pH, and sodium chloride concentration on the partitioning behavior of hors eradish peroxidase from Armoracia rusticana root extract was investiga ted in poly(ethyleneglycol)/sodium phosphate systems. PEG molecular we ight strongly affects the enzyme partition coefficient, whereas pH var iation from 5.5 to 8.0 has little effect. The addition of sodium chlor ide (8% w/w) to a PEG 1540/phosphate system, pH 7.0, raises the peroxi dase partition coefficient 13.5-fold without important changes in that of total horseradish root proteins. Moreover, these conditions allow direct homogenization of the A. rusticana roots with the selected aque ous two-phase system with the clear top phase containing over 90% of t he enzyme and the purification factor being 4.8.