How can I increase the expression level of a protein?

For recombinant proteins, expression can be increased by a variety of strategies. One of these strategies is to improve the solubility of the protein; this can be done by lowering the temperature or using a growth medium that contains all the necessary nutrients for the cell. The use of fusion tags can also improve the solubility of the protein. Another strategy is to improve purification of the protein, which can be done by various chromatography methods such as IMAC (immobilized metal affinity chromatography), AC (affinity chromatography), or SEC (size exclusion chromatography). In addition, gene synthesis can be utilized to optimize the codon sequence of the gene.