Molecular cloning and characterization of a new cDNA encoding a trypsin-like serine protease from the venom gland of Scolopendra subspinipes mutilans

A cDNA encoding a new putative serine protease, named Ssmase, was cloned and characterized from the venom gland of the centipede Scolopendra subspinipes mutilans. The cDNA sequence was 1029 bp length, including a 780 bp open reading frame (ORF), a 105 bp 5’ untranslated region, and a 144 bp 3’ untranslated region. The precursor nucleotide sequence of Ssmase was deduced to encode a prepro-peptide of 19 residues and a mature protein of 240 residues. The 19 amino acid residues prepro-peptide of Ssmase putatively composed of 14 amino acids of pre-peptide and 5 amino acids of propeptide (QGSSA). The mature protein of Ssmase contained the typical domain of a trypsin-like serine protease, where His61, Asp108 and Ser208 were the principal residues of the catalytic center. The cysteine residues at 46 to 62, 141 to 214, 180 to 195 and 204 to 233 possibly formed four pairs of disulfide bridges. Ssmase was found to have five N-glycosylation sites (N-Xaa-T/S). To the best of our knowledge, Ssmase was a trypsin-like serine protease firstly characterized from centipede venoms. Ssmase represented a new family of trypsin-like serine protease with four disulfide bridge motif.   Key words: Centipede, Scolopendra subspinipes mutilans, trypsin-like serine protease, cysteine motif.