A novel serine protease inhibitor from the venom of Vespa bicolor Fabricius.

Hornets possess highly toxic venoms, which are rich in toxin, enzymes and biologically active peptides. Many bioactive substances have been identified from wasp venoms but only a few serine protease inhibitors have been identified from two kinds of wasp venoms. In this work, a serine protease inhibitor named bicolin was purified and characterized from the venom of the wasp, Vespa bicolor Fabricius. The precursor encoding bicolin was cloned from the cDNA library of the venomous glands. It is a cysteine-rich small protein containing 54 amino acid residues including 6 half-cysteines. The peptide is homologous to serine protease inhibitors isolated from venoms of Anoplius samariensis and Pimpla hypochondriaca. Bicolin showed inhibitory ability against trypsin and thrombin.