Selection for Soluble Proteins via Fusion with Chloramphenicol Acetyltransferase

The low solubility of a protein is one of the most frequent impediments for its structural and functional analysis and, on a more practical aspect, for its application as an industrial enzyme. The reason for low solubility can lie in low conformational stability (1 ), in a high number of surface-exposed hydrophobic amino acids (2 ) or in certain structural features, such as membrane binding regions (3 ). By changing the amino acid sequence of these proteins, their solubility can be significantly improved (4 ,5 ). Hence a general method that can efficiently identify (i.e., select) more soluble protein variants from a large repertoire is very useful in evolving such proteins.