The present invention relates generally to a novel chymotrypsin that exhibits resistance to a plant serine proteinase inhibitor. More particularly, the present invention provides a chymotrypsin which is up-regulated in the gut of Helicoverpa armigera and Helicoverpa punctigera insect larvae when fed the serine proteinase inhibitors of Nicotiana alata. The novel chymotrypsin represents, therefore, a target for the identification of antagonists including inhibitors which are proposed to be useful in the control of Helicoverpa spp. populations that have become resistant to serine proteinase inhibitors produced in plants. The antagonists of the chymotrypsin may be topically applied to the plants or, when in proteinaceous form, may be produced by genetic means in plant cells. The antagonists may act at the level of gene expression or protein activity.

Hexima Limited

Insect chymotrypsin and inhibitors thereof

The invention provides isolated nucleic acids and their encoded polypeptides that are involved in enhancing the essential amino acid content of a plant. The polypeptide may be derived from a protease inhibitor, and more specifically, a chymotrypsin inhibitor. Chymotrypsin inhibitors that may be modified for use in the invention are present in many plant species. Barley (Hordeum vulgare) was initially used to obtain the chymotrypsin inhibitor modified for use in the present invention. Other plant species that may be used as a source for chymotrypsin inhibitor for use in the present invention include Zea Mays, Vicia faba, Cucurbita maxima, Canavalia lineata, Vigna angularis, Nicotiana tabacum, Nicotiana sylvestris, Sambucus nigra, Momordica charantia, Solanum tuberosum, Lycopersicon peruvianum, Lycopersicon esculentum, Amaranthus caudatus and Arabidopsis thalania. Optionally there is also a decrease in protease inhibitory activity of the polypeptide. The invention further provides recombinant expression cassettes, host cells, transgenic plants, and antibody compositions. The present invention provides methods and compositions relating to increasing essential amino acid content of plants for feed.

chymotrypsin/nicotiana

Insect chymotrypsin and inhibitors thereof

Proteins with increased levels of essential amino acids

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