Galacturonic
acid was used as a standard of reductive group, and the controls
without incubation were set. Endo-PG activity was
determined with the similar method, but the pH of acetate buffer
was 4.0 and the reaction did not need the presence of Ca2+. The
specific activity of enzyme was expressed as U mg1 protein, while
one activity unit (U) was 1 mmol L1 galacturonic acid released per
mg protein per h..