Erythropoietin produced in a human cell line (Dynepo) has significant differences in glycosylation compared with erythropoietins produced in CHO cell lines.

Recombinant human erythropoietin has been used to treat anemia associated with chronic renal disease. This paper provides a comprehensive comparative analysis of Dynepo and three other commercial erythropoiesis stimulating agents, Eprex, NeoRecormon and Aranesp. We found significant differences in the type, levels and amount of O-acetylation of sialic acids.

Peptide mapping with liquid chromatography using a basic mobile phase.

A new peptide mapping with liquid chromatography (LC) using an ammonia-containing basic mobile phase was reported. As compared with a method under a traditional acidic condition with a mobile phase containing trifluoroacetic acid (TFA) or formic acid (FA), the new method exhibited excellent overall performance: it was advantageous over the TFA method in terms of the ultraviolet (UV) and mass spectrometry (MS) sensitivities and the sequence coverage for a tryptic map; it was superior to the FA method in terms of the UV sensitivity, the sequence coverage and the separation capacity. Due to a significant difference in the chromatographic selectivity, several important peptide mapping applications that were sometimes difficult to be conducted previously could now be carried out using the new method.

Challenges in the development of high protein concentration formulations.

Development of formulations for protein drugs requiring high dosing (in the order of mg/kg) may become challenging for solubility limited proteins and for the subcutaneous (SC) route with <1.5 mL allowable administration volume that requires >100 mg/mL protein concentrations. Development of high protein concentration formulations also results in several manufacturing, stability, analytical, and delivery challenges.

Asparagine deamidation in recombinant human lymphotoxin: hindrance by three-dimensional structures.

The chemical stability of recombinant human lymphotoxin (rhLT) was evaluated at pH 7, 9, and 11 and 40 degrees C using quantitative tryptic map and urea-IEF methods. Degradation products were characterized by mass spectrometry. The stability of denatured rhLT protein was also evaluated to elucidate the effects of three-dimensional structures on Asn deamidation in rhLT.