CRM197 is a non-toxic mutant of diphtheria toxin used as a carrier protein carrier for polysaccharides and haptens enhancing their immunigenicity for vaccine applications.

To support its customers Xpress Biologics has developped a microbial expression system and a fully scalable industrial production process and provides High Quality recombinant CRM197

Production scale 

Xpress Biologics recombinant CRM197 is produced as periplasmic protein using a proprietary E. coli BL21(T7) strain allowing milligrams for research to kilograms for commercial production.

Production Grade

  • R&D : for in vitro and small animal assays
  • GLP : for GLP preclinical assays
  • GMP : for use in human (available in Q2 2022)

Product Sheet

Tests Control methods Expected Values
Identity SDS-PAGE in reducing conditions Single band between 50-65 kDa
Western-Blot (WB) in reducing conditions Single band between 50-65 kDa


Rt similar to reference
SE-HPLC Rt similar to reference
IEF Single band between pI 5-6
Purity SDS-PAGE in reducing conditions > 95% CRM


> 95% CRM
Impurities Residual E.coli host cell protein by WB Absence of HCP bands
Residual E.coli host cell protein by ELISA < 0.1% HCP
Endotoxin content by LAL < 20 EU/mg
Genomic DNA quantification by qRT-PCR < 0.1% w/w