Proteins are the working molecules of all biological systems and participate in a majority of cellular chemical reactions and biological processes. Knowledge of the properties and function of these molecules is central to an understanding of chemical and biological processes. In this context, purified proteins are a starting point for biophysical and biochemical characterization methods that can assist in the elucidation of function. The challenge for production of proteins at the scale and quality required for experimental, therapeutic and commercial applications has led to the development of a diverse set of methods for heterologous protein production. Bacterial expression systems are commonly used for protein production as these systems provide an economical route for protein production and require minimal technical expertise to establish a laboratory protein production system.