Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses IZI-BB
Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses IZI-BB

Protein Labeling & Modification

There are 20 basic amino acids that make up every protein in the natural world – with a few exceptions. Due to this limited number of amino acids, there are also limitations in terms of the biochemical and biophysical properties of the desired functional proteins.

Potsdamer Tag der Wissenschaften – Rotkohl ändert seine Farbe in Abhängigkeit des pH-Werts
© Fraunhofer IZI-BB
Labeling with fluorescent dyes

The Cell-free Protein Synthesis Unit offers a reliable method for introducing chemically modified amino acids with highly diverse reactive groups into cell-free synthesized proteins at specific positions. Amber suppression is the underlying method for this. In addition, we use click chemistry to couple fluorescent dyes, sugar structures, PEGylations and biotinylations to the reactive groups of the amino acids being introduced. Our methods are particularly well-suited for structural analysis and functional identification of membrane proteins, as well as for the screening of new kinds of ligands and therapeutic substances. Proteins can also be selectively modified in this way to identify new functions that may be used for treatment purposes.

Cell-free protein synthesis

Inserting of amino acids by amber suppression
© Fraunhofer IZI-BB
Inserting of amino acids by amber suppression

Service offer

  • Cell-free protein synthesis of difficult-to-produce proteins
  • Embedding of chemically modified amino acids at integrated amber positions
  • Coupling of fluorescent dyes, sugar residues, biotin and polymers (PEGs) to the target protein, both by copper-catalyzed and copper-free click reactions
  • Design of DNA templates with matching amber codon position
    • ailor-made selection of the position and introduction of the amber codon into a specific gene sequence
    • Evaluation of the efficiency of different amber codon positions to optimize the synthesis yield
    • Analysis of the coupling efficiency
  • Characterization of modified, cell-free synthesized proteins by microscopy and autoradiography
  • Interaction and ligand binding studies