In vitro selection of other proteins than antibodies by means of ribosome display

The in vitro selection and simultaneous evolution of proteins is feasible by means of ribosome display. Here, we describe the use of a protein bearing a binding property without being an antibody for affinity enrichment of the ternary complex, consisting of a protein, a ribosome and a encoding mRNA. The binding property was a simple affinity tag, namely Strep-tag II and His-tag. We could demonstrate that the selection of a specific mRNA encoding a shortened bovine heart fatty acid binding protein with a N-terminal His-tag was possible. After nine cycles of transcription, translation, affinity selection and reverse transcription PCR the protein with the His-tag could be enriched 10(8)-fold.