DEGRADATION OF PHEROMONE BIOSYNTHESIS-ACTIVATING NEUROPEPTIDE (PBAN) BY HEMOLYMPH ENZYMES OF THE TOBACCO HORNWORM, MANDUCA-SEXTA, AND THE CORN-EARWORM, HELICOVERPA-ZEA

The tritium-labeled bis-norleucine analog of Helicoverpa tea pheromone biosynthesis-activating neuropeptide ([H-3]NLPBAN) was incubated in v itro with hemolymph from Manduca sexta or H. tea adult females. The in cubations resulted in the formation of several tritium-labeled degrada tion products. At a [3H]NLPBAN concentration of 0.9 mu M the degradati on proceeded at a very slow but physiologically plausible rate (2-10 f mol/min/mu l hemolymph). The primary [H-3]NLPBAN degradation reaction in M. sexta hemolymph was not inhibited by 20 mu M leupeptin, 0.1 mM a mastatin, 1 mM EDTA, 1 mM EGTA, 1 mM 1,10-phenanthroline, or 2 mM 4-(2 -aminoethyl) benzenesulfonyl fluoride; but secondary reactions may hav e been affected, as some of the inhibitors changed the radio-HPLC prof ile of the degradation products. It is concluded that hemolymph of M. sexta and H. zea contains peptidase(s) capable of inactivating circula ting PBAN.