Abstract: To explore the expression and chitin-binding manner of chondroitin proteoglycans 1 of Toxocara canis (TcCPG1) and to provide a basis for the functional study of this proteins in T. canis. In the present work, the chondroitin proteoglycans 1 gene(Tc-cpg-1)of T. canis was molecularly cloned and expressed in a prokaryotic expression system for recombinant protein TcCPG1, which was then purified using Ni-NTA affinity chromatography and tested in a chitin-binding assay. Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to determine the transcriptional differences of Tc-cpg-1 between sexes and among tissues of T. canis. The results showed that the coding sequence of Tc-cpg-1 was 1 251 bp in length, encoding 417 amino acids. SDS-PAGE analysis showed that the recombinant protein TcCPG1 was expressed in inclusion bodies, and the molecular weight was estimated at~70 ku. Optimized conditions (induction by 0.8 mmol·L^-1 IPTG for 14 h and incubation at 16℃) facilitated an efficient production of the recombinant protein TcCPG1. Following Ni-NTA affinity purification, the recombinant protein bound chitin, suggesting a chitin-binding activity of TcCPG1. In addition, differential analysis showed a high transcriptional level of Tc-cpg-1 in female adult worm, particularly in the reproductive tissues, indicating potential roles of Tc-cpg-1 in reproductive process (embryonic and reproductive development) of female worms, which might be achieved by interacting with the chitin in egg shell.

Key words: Toxocara canis, CPG1, prokaryotic expression, chitin-binding assay