Occurrence and Heterogeneity of Chymotrypsin Inhibitors in Vegetative Tissues of Barley

Inhibitors of chymotrypsin and the alkaline proteinase of Aspergillus oryzae were present in the shoots of barley seedlings and weak activities were also detected in the shoot tops of 6‐week‐old plants. Treatments which induce inhibitor formation in tomato and potato leaves had no effect when tested on mature leaves, seedlings, or young tillers of barley. Fractionation experiments with isoelectric focusing showed that the barley leaves contained several proteinase inhibitors acting on both chymotrypsin and the Aspergillus proteinase, and one inhibitor which acted only on the Aspergillus enzyme. All of these inhibitors were different from the five Aspergillus proteinase inhibitors which are abundant in the endosperm of resting seeds. Two chymotrypsin inhibitors with weaker activity on the Aspergillus proteinase were present in rootlets and also in embryos of resting seeds. These inhibitors were different from both the endospermal inhibitors and the inhibitors present in young leaves.