Patent Evaluation: Systematic Polypeptide Evolution by Reverse Translation

Summary

Novelty: A method for selecting a polypeptide ligand which specifically binds any target molecule is reported.

Biology: The method of Systematic Polypeptide Evolution by Reverse Translation (SPERT) is described. A mixture of translatable mRNAs, which each contain a translation initiation coder, a ribosome binding site and a polypeptide coding region, are translated in vitro. Translation is stalled and ribosome complexes, including the mRNA and the nascent peptide, are isolated. The isolates are partitioned by the ability of the nascent peptide to bind a desired target molecule. Subsequently, the mRNA molecules are separated from the complexes and amplified by conventional methods before being subjected to a further round of translation and enrichment. Those cycles can be reiterated until a desired binding affinity is achieved, and the mRNA can then be cloned or sequenced. The technique is illustrated by the isolation of polypeptide ligands directed towards immunoglobulin molecules, a bacteriophage DNA binding protein, a serine protease, the IL-1 receptor and specific DNA sequences.