A Newly Identified Impurity in Polysorbate 80, the Long-Chain Ketone 12-Tricosanone, Forms Visible Particles in a Biopharmaceutical Drug Product.

Visible particles linked to polysorbates (PSs) used in biopharmaceutical drug products (DPs) have been observed repeatedly in recent years as an industry-wide issue, with PS degradation and insoluble degradation products, especially fatty acids and fatty acid esters, being suspected as root cause. We have shown that the visible particles observed in a monoclonal antibody DP solution in vials after 18 months of long-term storage at 5 ± 3°C were neither linked to reduction in PS (PS80) concentration nor to any known PS degradation product, but consist of 12-tricosanone, an impurity present in the raw material PS80, not a degradation product. The occurrence of visible 12-tricosanone particles in DP correlated with the usage of specific PS80 raw material lots, where 12-tricosanone was found as impurity at elevated levels.

The Effect of Shear on the Structural Conformation of rhGH and IgG1 in Free Solution.

The effect of hydrodynamic forces on proteins in free solution, also referred to as shear stress in multiple drug substance and drug product processing steps, was investigated by means of in situ and inline biophysical measurements. The use of a quartz Couette cell in combination with a circular dichroism spectrometer allowed simultaneously the creation of simple shear flow and direct measurements of the proteins' secondary and tertiary structure. Recombinant human growth hormone and an IgG1 mAb were chosen as model proteins.

The C-terminal region of cellular Qin oligomerizes: correlation with oncogenic transformation and transcriptional repression.

Expression of the oncoprotein Qin induces tumors in chickens and oncogenic transformation of chicken embryo fibroblasts in culture. We performed a detailed deletion analysis of the C-terminal region of Qin (amino acids 246-451, extending from the winged helix domain to the C-terminus) and identified amino acids 246-379 as important for transformation. The same region mediates homo-oligomerization of Qin as documented in vitro by GST pulldowns and in vivo by coimmunoprecipitation.

Binding of the corepressor TLE1 to Qin enhances Qin-mediated transformation of chicken embryo fibroblasts.

The oncoprotein Qin is a member of the winged helix family of transcriptional regulators. The region C-terminal to its winged helix DNA-binding domain is required for transformation of chicken embryo fibroblasts. We isolated the corepressor TLE1 as a binding partner for Qin in a yeast two-hybrid screen and localized the TLE1-binding region to a 60 amino-acid stretch directly C-terminal of the winged helix domain of Qin.

Small-molecule antagonists of Myc/Max dimerization inhibit Myc-induced transformation of chicken embryo fibroblasts.

Myc is a transcriptional regulator of the basic helix-loop-helix leucine zipper protein family. It has strong oncogenic potential, mutated or virally transduced forms of Myc induce lymphoid tumors in animals, and deregulated expression of Myc is associated with numerous types of human cancers. For its oncogenic activity, Myc must dimerize with the ubiquitously expressed basic helix-loop-helix leucine zipper protein Max.