Abstract
Hog kidney mutarotase was separated into four forms (types I-IV) by DEAE-cellulose column chromatography. The most abundant form (type II) was purified to homogeneity as judged by polyacrylamide disc gel electrophoresis. The physico-chemical properties of the pure type II enzyme were as follows : molecular weight, 41000 ; isoelectric point, pH 5.48 ; Km for α-D-glucose at pH 7.4 and at 25°, 19 mM ; optimum pH, 6.5-7.5 ; optimum temperature, 30°. The enzyme activity was greatly reduced at acid pH below 6.0. The enzyme lost little activity on storage for at least 130 days at 4°, whereas about 12% of the activity was lost during the same period at -20°. When the enzyme was heated for 10 min at 59°, the activity was completely lost.
