Isoenzymes of acid phosphatase in germinating peas.

Acid phosphatase activity in pea cotyledons increases during germination. Gel filtration separates three isoenzymes with pH optima of 4.9, 5.6 and 6.0. The relative activities of these isoenzymes change during germination. The increase in activity is confined to two of the three isoenzymes. Density-labelling experiments whow that these are synthesised de novo. Activity of the third isoenzyme, which is present in dry seeds, does not change significantly during germination, and is not affected by cycloheximide but is lost on freezing. The possible localization of each isoenzyme is discussed in the light of these findings and in relation to histochemical studies.