New assay for quantification of PEGylated proteins during in vitro permeability studies.

One of the major challenges when analyzing very low amounts of PEGylated proteins is finding a sensitive analytical method. Immunoassays are most frequently used, however, conjugation can partially or completely mask protein epitopes, which can substantially lower the response and influence the quantitation range. Here we describe a novel assay that allows quantification of low amounts of PEGylated or differently conjugated proteins.

Cysteine-specific PEGylation of rhG-CSF via selenylsulfide bond.

A new PEGylation reagent enabling selective modification of free thiol groups is described in this article. The reagent was synthesized by attaching linear polyethylene glycol (PEG) N-hydroxysuccinimide to selenocystamine. The reaction was very fast, resulting in over 95% conversion yield.

The Characterization and Potential use of G-CSF Dimers and their Pegylated Conjugates.

G-CSF successfully prevents chemotherapy-induced neutropenia. Two second-generation drugs with improved therapeutic properties are already available and the development of new forms is still ongoing. For an efficient receptor dimerization two G-CSF molecules have to bind.

Beta-lactamase reporter system for selecting high-producing yeast clones.

In modern production of protein biopharmaceuticals, a good screening and selection method of high-producing clones can dramatically influence the whole production process and lead to lower production costs. We have created a rapid, simple, and inexpensive method for selecting high-producing clones in the yeast Pichia pastoris that is based on the beta-lactamase reporter system. By integrating the reporter gene and the gene of interest into the same genome locus, it was possible to use beta-lactamase activity as a measure of the expression level of the protein of interest.