HYDROLYSIS PATTERN OF PROCASOMORPHIN BY GUT PROTEASES FROM PLANT PARASITE HELIOTHIS-ZEA, DETERMINED BY SEQUENCE ANALYSES PERFORMED ON THE UNFRACTIONATED DIGESTION MIXTURES

The digestion pattern of procasomorphin, a putative precursor of beta- casomorphins (beta-casein-derived opioid peptides), by gut proteases f rom the plant parasite insect Heliothis tea has been determined to eva luate the possibility of introducing in plants the gene encoding for t his peptide in order to confer resistance to damage by the insect. The method we used is based on the possibility of deducing the sequence o f the fragments produced by proteases at different times of digestion by means of automatic Edman degradation performed on the fragment mixt ures without any purification steps. This approach can be considered o f general utility in studying the digestion of peptides by a mixture o f proteases. (C) Munksgaard 1994.