Objective:To explore the method of secretory expression of recombinant human mutant oncostatin M(rhMut-OSM) in Pichia pastoris.Methods:First

optimize the gene of human oncostatin M( hOSM)

change Asn100 and Asn217 to Glu100 and Glu217 respectively to remove N-glycosylation recognition sites.The sequence of mature rhMut-OSM gene was obtained by synthesis

the expression vector of Pichia pastoris of pPIC9-rhMut-OSM was constructed.The recombinant plasmid was transformed into Pichia pastoris GS115 via electroporation.The transformed positive strains were screened by PCR.The supernatant were analyzed by SDS-PAGE and Western blotting to screen Pichia pastoris engineer strain with highly effective expression of rhMut-OSM.Results:SDS-PAGE and Western blotting analysis showed that there was non-glyxosylated rhMut-OSM in the culture supernatant induced by methanol with 22 000 of molecular weight.The expression peak emerged after 72 h induced with expression level of 400 mg/L. Conclusion:Genetic Engineering Strain Expressed rhMut-OSM was constructed successfully.Pichia pastoris can express rhMut-OSM efficiently and stably.