Gazit, Y., Institute of Plant Protection, ARO, The Volcani Center, Bet Dagan, 50250, Israel
Dunkelblum, E., Institute of Plant Protection, ARO, The Volcani Center, Bet Dagan, 50250, Israel
Benichis, M., Institute of Plant Protection, ARO, The Volcani Center, Bet Dagan, 50250, Israel
Altstein, M., Institute of Plant Protection, ARO, The Volcani Center, Bet Dagan, 50250, Israel

The activity of synthetic Heliothis zea PBAN (Hez-PBAN) and four shorter peptides on the sex pheromone biosynthesis in Heliothis peltigera was investigated in order to characterize their biological potency, and to determine the structure-activity relationship. Hez-PBAN (PBAN 1-33) is very potent and stimulates sex pheromone biosynthesis at the picomolar range both in photophase and scotophase. Removal of eight amino acids from the N-terminal region of the peptide Hez-PBAN had only a minor effect on the biological activity. A shorter fragment of Hez-PBAN, lacking 18 amino acids from the N-terminus, was less active. Two short peptides, consisting of eight and six amino acids, derived from the C-terminal region of Hez-PBAN had very little biological activity. In addition, it was found that PBAN 1-33 undergoes oxidation during storage. The oxidation of the peptide resulted in a loss of its biological activity, which could be restored by reduction with N-methylmercaptoacetamide. Unlike PBAN 1-33, PBAN 9-33 did not lose activity as a function of time, and its activity was fully preserved after prolonged storage. The results indicate that PBAN 1-33 and PBAN 9-33 have similar activities, and that the sequence containing the eight N-terminal amino acids is not essential for the biological activity of Hez-PBAN on the biosynthesis of H. peltigera sex pheromone. © 1990.