A novel bradykinin-related peptide from skin secretions of toad Bombina maxima and its precursor containing six identical copies of the final product

Amphibian skin contains rich bradykinin-related peptides, but the mode of b iosynthesis of these peptides is unknown. In the present study, a novel bra dykinin-related peptide, termed bombinakinin M, was purified from skin secr etions of the Chinese red belly toad Bombina maxima. Its primary sequence w as established as DLPKINRKGPRPPGFSPFR that comprises bradykinin extended fr om its N-terminus by a 10-residue segment DLPKINRKGP. The cDNA structure of bombinakinin M was found to contain a coding region of 624 nucleotides. Th e encoded precursor of bombinakinin M is composed of a signal peptide, an a cidic peptide, six 100% identical copies of a 28-amino-acid peptide unit in cluding bombinakinin M plus a spacer peptide. The sequence of bombinakinin M is preceded by a single basic residue (arginine), which represents the si te of cleavage for releasing of mature bombinakinin M. This is the first cD NA cloning of bradykinin-related peptides from amphibian skin. The unique c DNA structure encoding bombinakinin M suggests that the generation modes of bradykinin-related peptides in amphibian skin and in mammalian blood syste m are different. (C) 2001 Academic Press.