[Expression of HCGbeta-CTP polymeride by the methylotropic yeast, pichia pastoris and structure prediction of the expressed products].

To investigate the expression of CTP encoding gene in the methylotropic yeast, pichia pastoris and the possibility of CTP acting as an antifertility vaccine or anti-cancer vaccine, we strung two, three or four CTP cDNA to construct CTP polymeric cDNA in order to enhance the immunogenicity of the CTP. Then, the recombinant genes were subcloned into a pichia pastoris expression vector pPIC9K to construct pPIC9K-(hCGbeta-CTP37)n(n = 2,3,4). After identified by restriction endonuclease digestion and DNA sequencing, the recombinant vectors were linearized and transferred into GS115 by electroporation. The induced culture supernatant was precipitated by PEG6000 and the precipitate was washed by 75% alcohol. SDS-PAGE and RIA analysis suggested GS115 expressed the recombinant genes successfully and the recombinant protein had anti-hCG antibody binding activity. In addition, ANTHEPROT 4.3 software was used to analyze the protein structure of CTP quadrigeminum. We found that CTP quadrigeminum had similar secondary structure with hCGbeta, but the speciality of antigen better than that of the latter. Therefore, we conclude that this study prepared basic necessary data for developing antifertility vaccines or anticancer vaccines basing on hCGbeta--CTP37.