Analysis of the physical properties of biotherapeutic proteins is crucial throughout all the stages of their lifecycle. Herein, we used size-exclusion ultra high performance liquid chromatography coupled to multiangle light scattering and refractive index detection systems to determine the molar mass, mass-average molar mass, molar-mass dispersity and hydrodynamic radius of two monoclonal antibodies (rituximab and trastuzumab), a fusion protein (etanercept), and a synthetic copolymer (glatiramer acetate) employed as models. A customized instrument configuration was set to diminish band-broadening effects and enhance sensitivity throughout detectors. The customized configuration showed a performance improvement with respect to the high-performance liquid chromatography standard configuration, as observed by a 3 h column conditioning and a higher resolution analysis in 20 min. Analysis of the two monoclonal antibodies showed averaged values of 148.0 kDa for mass-average molar mass and 5.4 nm for hydrodynamic radius, whereas for etanercept these values were 124.2 kDa and 6.9 nm, respectively. Molar-mass dispersity was 1.000 on average for these proteins. Regarding glatiramer acetate, a molar mass range from 3 to 45 kDa and a molar-mass dispersity of 1.304 were consistent with its intrinsic peptide diversity, and its mass-average molar mass was 10.4 kDa. Overall, this method demonstrated an accurate determination of molar mass, overcoming the difficulties of size-exclusion chromatography.
Keywords: Biotherapeutic proteins; Hydrodynamic radius; Multiangle light scattering; Synthetic copolymers; Ultra high performance liquid chromatography.
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.