Abstract: A method for the solubilization and/or naturation of a somatotropin involves contacting a somatotropin with a detergent composition and water under conditions effective to obtain a naturated somatotropin, wherein the detergent composition may be a C10, C12, C16 or C18 acyl glutamate, a C10, C14 or C18 alkyl sulfate, an alcohol ethoxy sulfate, lauroyl ethylenediamine-triacetic acid (LEDA), a C10 to C18 linear alkyl benzene sulfonate, diphenyl disulfonate or an acyl amino acid.

Abstract: A composition for expression of a protein-encoding gene in a host cell is described, making use of an heterologous regulon. This composition provides a protein-encoding gene under control of a promoter heterologous to the host cell, and a gene for an RNA polymerase, preferably a single-subunit RNA polymerase that recognizes the promoter heterologous to the host cell. The gene for the RNA polymerase is under control of an inducible promoter recognized by the host cell. Also disclosed is a method for expressing the protein-encoding gene using the composition described.