This invention involves NGAL protein, and disclosed the recombinant Pichia pastoris and methods of expression of NGAL with Pichia pastoris. High expression of recombinant Pichia pastoris strains were obtained through PCR amplification, ligation, transformation and screening. The strain can excrete target protein into the medium and the protein concentration can reach to more than 100 mg / L, but no contaminant proteins. This makes the purification process becomes very simple: the broth was precipitated by ammonium sulfate, desalted, and separated by cation exchange chromatography. The products are superior to protein derived from prokaryotes, The glycosylation is integrate, and it is available for functional studies and clinical testing standards of NGAL protein. |