In this issue: Biotechnology Journal 4/2011

Mutation detection in biopharmaceutical plasmids Oliveira et al., Biotechnol. J. 2011, 6, 378–391 The number of applications involving therapeutic plasmid DNA (pDNA) for DNA vaccinations and gene therapy is increasing worldwide. This creates a demand for production of large amounts of stable and purified molecules that conform to Good Manufacturing Practice guidelines and comply with the regulatory policies of the FDA or EMA. Efficient, cost‐effective and sensitive technologies enabling the identification of genetic variants and unwanted side products are needed to successfully establish the identity and stability of a plasmid‐based biopharmaceutical. In this issue, authors from Lisbon, Portugal, and the MIT (Cambridge, MA, USA) review bioinformatic tools for ab initio detection of potentially unstable DNA regions and techniques used for mutation detection in nucleic acids as well as practical examples from studies using pDNA. Semi‐continuous magnetic PEGylation Ottow et al., Biotechnol. J. 2011, 6, 396–409 The applications of polypeptide‐based biocatalysts, enzymes, and pharmaceuticals are of growing interest. The most successful technique to enhance their activity and stability is via the addition of polyethylene glycol polymer chains, i.e., PEGylation. In this issue Ottow et al. from the Technical University of Denmark in Lyngby describe a semi‐continuous magnetic particlebased process for the controlled attachment of PEG to proteins for the first time. Proof of concept was shown in a microfluidics system to minimize reagent consumption. Two streams containing the target protein trypsin and magnetic adsorbents were mixed with activated PEG and the reaction stopped with free amine groups. In a high‐gradient magnetic separator magnetic supports with bound PEGylated trypsin are captured and subsequently eluted. The extent of PEGylation could be controlled by varying the reaction time and PEG concentration. Immuno‐assay on chip Herwig et al., Biotechnol. J. 2011, 6, 420–427 Immunoaffinity‐based methods, such as western blottin or ELISA, are crucial analytical tools to detect and quantify proteins. They are however, time‐consuming and expensive. In this issue, the group of Günter Allmaier (Vienna University of Technology, Austria) in collaboration with Agilent Technologies (Waldbronn, Germany) report the development of an immunoprecipitation (IP) method combined with automated microchip capillary gel electrophoresis (IP‐MCGE) with laser‐induced fluorescence (LIF) detection for analysis of endogenous β‐galactosidase in crude E. coli cell lysates. Total cell lysates were derivatized with a fluorescence dye, incubated with anti‐β‐galactosidase antibodies, and the antigen/antibody complex was precipitated with protein G‐coated magnetic beads. The complex was eluted from the beads and loaded directly onto a multisample microchip for analysis. The developed IP‐MCGE method is more sensitive and faster than western blotting, and also requires less reagents.