To achieve high level recombinant protein production, we employ Protein Engineering, which is an advanced application of rDNA technology. This process is used to create and produce engineered proteins that have additional or extended properties, such as greater stability when exposed to elevated temperature, changes in pH, or the presence of organic solvents.

The process involves identifying the critical amino acids responsible for the desired trait. The codon sequences on the gene are then modified by creating point mutations through site directed mutagenesis. This allows specific amino acids to be mutated or replaced to modulate the desired activity of the protein.

A key example is the engineering of Subtilisin, a proteolytic enzyme used in detergents. To prevent the oxidation of Met 222 by bleach (which reduces enzyme action), the codon for Met 222 is replaced by the codon for Ala. This modification ensures the enzyme remains stable and effective. Additionally, proteins can be engineered with a 6-His-tag for ease of purification, allowing them to be efficiently purified on Nickel ion columns.

Protein engineering technology is also involved in the production of humanised monoclonal antibodies and recombinant immunotoxins. These engineered proteins serve as novel reagents for research, diagnostics, and therapeutics, demonstrating the versatility of genome engineering in protein production.