Protein engineering strategies for selective protein purification

When producing and purifying recombinant proteins it is of importance to minimize the number of unit operations during the purification procedure. This is accomplished by increasing the selectivity in each step. Due to the high selectivity of affinity chromatography it has a widespread use in protein purification. However, most target proteins lack a suitable affinity ligand usable for capture oil a solid matrix. A way to circumvent this obstacle is to genetically fuse the gene encoding the target protein with a gene encoding a purification tag. When the chimeric protein is expressed, the tag allows for specific capture of the fusion protein. In industrial-scale production, extension of the target protein often is unwanted since it might interfere with the function of the target protein. Hence, a purification scheme developed for the native protein is desired. In this review, different fusion strategies used for protein purification are discussed. Also, the development of ligands for selective affinity purification of native target proteins is surveyed.