Molecular cloning of capillary permeability-increasing enzyme-2 from Agkistrodon caliginosus (Korean viper)

The gene of capillary permeability-increasing enzyme-2 (CPI enzyme-2) was cloned from the cDNA library of Agkistrodon caliginosus and its nucleotide sequence was determined. Its sequence indicates that CPI enzyme-2 is synthesized as a pre-zymogen of 258 amino acid residues, including a putative secretory signal peptide of 18 amino acids and a proposed zymogen peptide of 6 amino acids. The amino terminal sequence deduced from the cDNA sequence was exactly consistent with that of CPI enzyme-2 except for the substitution of an amino acid (Gly(27) --> Ser). The open leading frame is very similar to those of plasminogen activator and thrombin-like protsases cloned from other snakes. The clone encoding CPI enzyme-2 belongs to the serine protease family The active site of the enzyme is highly conserved at His(41), Asp(86) and Ser(180) Its possible glycosylation sites, Asn-X-Thr/Ser, are located at amino acid residues 20-22, 55-57, 79-81 and 97-99. (C) 1998 Elsevier Science Ltd. All rights reserved.