Glycosylation characterization of recombinant human erythropoietin produced in glycoengineered Pichia pastoris by mass spectrometry

J Mass Spectrom. 2013 Dec;48(12):1308-17. doi: 10.1002/jms.3291.

Abstract

Glycosylation plays a critical role in the in vivo efficacy of both endogenous and recombinant erythropoietin (EPO). Using mass spectrometry, we characterized the N-/O-linked glycosylation of recombinant human EPO (rhEPO) produced in glycoengineered Pichia pastoris and compared with the glycosylation of Chinese hamster ovary (CHO) cell-derived rhEPO. While the three predicted N-linked glycosylation sites (Asn24, Asn38 and Asn83) showed complete site occupancy, Pichia- and CHO-derived rhEPO showed distinct differences in the glycan structures with the former containing sialylated bi-antennary glycoforms and the latter containing a mixture of sialylated bi-, tri- and tetra-antennary structures. Additionally, the N-linked glycans from Pichia-produced rhEPO were similar across all three sites. A low level of O-linked mannosylation was detected on Pichia-produced rhEPO at position Ser126, which is also the O-linked glycosylation site for endogenous human EPO and CHO-derived rhEPO. In summary, the mass spectrometric analyses revealed that rhEPO derived from glycoengineered Pichia has a highly uniform bi-antennary N-linked glycan composition and preserves the orthogonal O-linked glycosylation site present on endogenous human EPO and CHO-derived rhEPO.

Keywords: N-linked glycosylation; O-linked glycosylation; Pichia pastoris; mass spectrometry; rhEPO.

MeSH terms

  • Animals
  • CHO Cells
  • Cricetinae
  • Cricetulus
  • Erythropoietin / analysis
  • Erythropoietin / chemistry*
  • Erythropoietin / metabolism
  • Humans
  • Metabolic Engineering
  • Pichia / genetics
  • Pichia / metabolism*
  • Recombinant Proteins / analysis
  • Recombinant Proteins / chemistry*
  • Recombinant Proteins / metabolism
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Substances

  • Recombinant Proteins
  • Erythropoietin