Selection of Gallium-binding peptides using Phage Display technology

Gallium is used essentially in the semiconductor compounds GaAs, GaN or GaP for high-potential future technologies. The resulting rapidly growing demand for gallium shouldn't be exclusively met by the recovery from primary raw material sources.
Biosorptive recycling of gallium from waste waters of the semiconductor industry is a promising and innovative contribution for establishing an economic and clean zero waste technology.
Peptides are excellently suitable ligands for the biosorptive complexation of gallium ions in aqueous solutions due to their variability in their amino acid sequence and their robust properties.
A well-established method for the selection of highly specific peptide ligands in medicine and biotechnology is the phage display technology. Random, short peptide sequences are presented on the surface according to genetically modified bacteriophages. In a biopanning called process, a pool of different bacteriophages is selected against a particular target, thereby enriching specific binding clone variants (figure 1). A very effective method has been established for the selection of different phage display libraries. Gallium ions immobilized on a monolithic ion exchanger are made accessible for biopanning in an FPLC system. This chromatopanning allows the selective enrichment of gallium-binding clone variants under strictly controlled process conditions.
In the present study, we report about the enrichment, identification and characterization of several gallium-binding motifs. Some promising gallium binding bacteriophage clones are chosen for further binding studies. The corresponding peptide sequences can be synthesized and used in subsequent experiments to develop biosorptive materials for selective gallium recovery from industrial waste waters.