MAIZE LEAF PROTEASES AND THEIR EFFECT ON ENDOGENOUS INORGANIC PYROPHOSPHATASE

Several different proteolytic enzymes are present in leaf and root tissue of maize seedlings. The activity of these enzymes diminishes to a basal level by the time seedling height reaches 20-30 cm. We have partially characterized an endopeptidase with trypsin-like specificity and two aminopeptidases, all from leaf tissue, and compared them to previously reported proteases from maize. Both the endopeptidase and the aminopeptidases degrade the maize leaf enzyme, inorganic pyrophosphatase. Modification of the pyrophosphatase by the peptidases results in the formation of catalytically active, electrophoretically distinct products. The aminopeptidases have little effect on several other maize leaf enzymes, but also modify yeast inorganic pyrophosphatase. © 1979.