Polygalacturonase (PG) was separated from ´Fuji´ apple fruits by gel filtration, ion exchange column chromatography and characterized by means of several biochemical methods. The results obtained are summarized as follows:
1. Two forms of isoenzymes, PG I and PG II, were detected, and the activity of PG I was much higher than that of PG II.
2. The Km and Vmax values of PG I were 1.54 ㎎/㎖ and 0.25 μmole reducing sugar/㎖/30 min, respectively.
3. The PG I was stable below 55℃ with the highest activity at 30℃.
4. The PG I was stable at pH between 3 and 8 with the highest activity at pH between 4 and 5.
5. The PG I activity was increased by Na^+ or Ca^(++), but was inhibited by Ag^+, Cu^(++), SDS, or EDTA.
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