Isolation and Structural Determination of Seminal Vesicle-specific Peptides of the Terrestrial Isopod, Armadillidium vulgare

During the course of purifying the androgenic gland hormone of the terrestrial isopod, Armadillidium vulgare, that induces post-embryonic sex differentiation, four structurally related peptides were obtained and their structures determined by a combination of microsequence and mass spectral analyses. These peptides were found to exist speciffically in the seminal vesicle and vas deferens by a Western blot analysis, therefore being designated as seminal vesicle-specific peptides (SVSPs). They had essentially the same amino acid sequences but differed from one another in the truncation of several residues at the N-terminus and of one residue at the C-terminus, and in the modification of glutamine to pyroglutamate at the N-terminus. The longest peptides, SVSP-4, consisted of 60 amino acid residues with two intramolecular disulfide bridges. There is no significant homology with any other vertebrate or invertebrate peptides.