Characterization of a carboxypeptidase inhibitor from the tick Haemaphysalis longicornis

Haiyan Gong, Jinlin Zhou, Min Liao, Takeshi Hatta, Thasaneeya Harnnoi, Rika Umemiya, Noboru Inoue, Xuenan Xuan, Kozo Fujisaki

Research output: Contribution to journalArticlepeer-review

Abstract

A carboxypeptidase inhibitor called HlTCI was isolated from Haemaphysalis longicornis in this study. The full-length cDNA of HlTCI contains an open reading frame (ORF) of 291bp, encoding 96 amino acid residues consisting of a predicted 19-residue signal peptide and a putative mature 77-residue protein. The expected mature protein is cysteine-rich and has 12 cysteine residues assumed to construct six disulfide bridges. The deduced peptide sequence shows 63.9% homology to the carboxypeptidase inhibitor from another ixodid tick, Rhipicephalus bursa. Reverse-transcription PCR (RT-PCR) indicated that HlTCI was specifically expressed in the ovary from partially engorged adult ticks. The recombinant protein of HlTCI (rHlTCI) with glutathione S-transferase (GST) was expressed in Escherichia coli strain BL21 (DE3) and purified by glutathione-Sepharose 4B beads. rHlTCI showed inhibitory activity against digestive metallocarboxypeptidases A and B, but the activity was affected by the increase of the temperature treatment. High concentrations of rHlTCI were shown to significantly accelerate fibrinolysis in vitro. This effect of rHlTCI on clot lysis suggests its promising potential for use in some thrombotic disorders.

Original languageEnglish
Pages (from-to)1079-87
Number of pages9
JournalJournal of Insect Physiology
Volume53
Issue number10
DOIs
Publication statusPublished - Oct 2007

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