The specific activity value based on the prosthetic copper of ascorbate oxidase

The copper content and activity data of 137 purified samples of ascorbate oxidase (l-ascorbate:O₂ oxidoreductase, EC 1.10.3.3) prepared in this laboratory during the period 1951–1977 have been examined and correlated. These data support the developing concepts of “active site heterogeneity” in otherwise homogeneous protein preparations. The specific activities, based on the copper contents of these 137 enzyme specimens, have been determined to average at about 760 units per μg copper and to reach maximum values in the area of 1000 units per μg copper. The maximum specific activity value (units per mg protein) and the copper content value of these purified specimens have been found to be 3800 ± 400 and 0.46 ± 0.06%, respectively.