Biochemical and biophysical characterization of humanized IgG1 produced in Pichia pastoris

The first full length IgG produced in Pichia pastoris was reported in late 1980. However, use of a wild-type Pichia expression system to produce IgGs with human-like N-linked glycans was not possible until recently. Advances in glycoengineering have enabled organisms such as Pichia to mimic human N-glycan biosynthesis and produce IgGs with human glycans on an industrial scale. Since there are only a few reports of the analytical characterization of Pichia-produced IgG, we summarize the results known in this field, and provide additional characterization data generated in our laboratories. The data suggest that Pichia-produced IgG has the same stability as that produced in Chinese hamster ovary (CHO) cells. It has similar aggregation profiles, charge variant distribution and oxidation levels as those for a CHO IgG. It contains human N-linked glycans and O-linked single mannose. Because of the comparable biophysical and biochemical characteristics, glycoengineered Pichia pastoris is an attractive expression system for therapeutic IgG productions.