Correlation between temperature-dependent cytoplasmic solubility and periplasmic export of a heterologous protein in Escherichia coli

Solubility and secretability

The solubility and secretability of proteins can often be affected by extremely small changes in their primary structure. Attempts to determine empirical rules for the alteration of protein structure to improve either of these characteristics have met with only partial success. Those (mostly serendipitous) improvements in solubility that have been obtained via mutagenesis cannot be considered to be 'protein engineering'. The most successful examples where directed mutagenesis has been used to alter protein solubility, hemoglobin and insulin, have relied on established crystal structures and a wealth of data about the relationship between sequence and structure of the targeted protein. Currently, optimizing culture growth conditions by trial and error remains the fastest way to improve expression.