Identification of a novel member of the paralytic peptide family in the silkmoth Antheraea yamamai

We found that cell-free hemolymph of the wild silkmoth, Antheraea yamamai contains a factor that induced paralysis of several body segments when injected into the caterpillars. The paralytic factor was isolated from the 5th instar larval hemolymph and the primary structure, NH2-GIu-Asn-Phe-Ala-Gly-Gly-Cys-Ala-Thr-Gly-Phe-Met-Arg-Thr-AlaAsp-Gly-Arg-Cys-Lys-Pro-Thr-Phe-COON, was determined by automated gas-phase Edman degradation, with pyridylethylated method, and by mass spectrometry. The isolated peptide was classified as a new member of the paralytic peptide family identified in lepidopteran insects. Synthetic peptide was tested in a bioassay with the 5th instar larvae of Bombyx mori: ED50 was 170 nM and LD50 between 100 aM and 1 mM.