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Abstract: Affibody molecules are a class of engineered affinity proteins with proven potential for therapeutic, diagnostic and biotechnological applications. Affibody molecules are small (6.5kDa) single domain proteins that can be isolated for high affinity and specificity to any given protein target. Fifteen years after its discovery, the Affibody technology is gaining use in many groups as a tool for creating molecular specificity wherever a small, engineering compatible tool is warranted. Here we summarize recent results using this technology, propose an Affibody nomenclature and give an overview of different HER2-specific Affibody molecules. Cumulative evidence suggests that the three helical scaffold domain used as basis for these molecules is highly suited to create a molecular affinity handle for vastly different applications. [Copyright &y& Elsevier]

Aims: The study was conducted with an aim to optimize the transformation efficiency of the Gram-positive bacterium Staphylococcus carnosus to a level that would enable the creation of cell surface displayed combinatorial protein libraries. Methods and Results: We have thoroughly investigated a number of different parameters for: (i) the preparation of electrocompetent cells; (ii) the treatment of cells before electroporation; (iii) the electroporation step itself; and (iv) improved recovery of transformed cells. Furthermore, a method for heat-induced inactivation of the host cell restriction system was devised to allow efficient transformation of the staphylococci with DNA prepared from other species, such as Escherichia coli. Previously described protocols for S. carnosus, giving transformation frequencies of approximately 102 transformants per transformation could be improved to reproducible procedures giving around 106 transformants for a single electroporation event, using plasmid DNA prepared from either S. carnosus or E. coli. The transformed staphylococcal cells were analysed using flow cytometry to verify that the entire cell population retained the introduced plasmid DNA and expressed the recombinant protein in a functional form on the cell surface at the same level as the positive control population. Conclusions: The results demonstrate that the transformation frequency for S. carnosus could be dramatically increased through optimization of the entire electroporation process, and that the restriction barrier for interspecies DNA transfer, could be inactivated by heat treatment of the cells prior to electroporation. Significance and Impact of the Study: The generation of large combinatorial protein libraries, displayed on the surface of S. carnosus can be envisioned in the near future, thus dramatically improving the selection compared with the traditional biopanning procedure used in phage display. [ABSTRACT FROM AUTHOR]