Abstract: This invention provides a method for solubilizing and recovering in bioactive form, a target polypeptide or protein that has been expressed from a host organism in insoluble form. The polypeptide is isolated from the host organism by standard procedures including disrupting the host cell to produce a lysate and recovering the precipitate from the lysate. The precipitate containing the polypeptide is solubilized in a non-denaturant and detergent free non-buffered solubilization solution containing sodium hydroxide between 8 and 10 mM, mannitol between 2 and 5 mM and lactose between 1 and 2 mM. The resultant solubilization preparation contains a biologically active target polypeptide between 1 and 4 mg per ml of solubilization solution. The solubilized polypeptide obtained in this particular manner constitutes the object of the invention.

Abstract: This invention entails a method for solubilizing and recovering, in bioactive and isolated form with retained native state configuration, a target peptide from a host organism in which the heterologous polypeptide is present in insoluble form. Broadly this method comprises (i) disrupting the host cell to produce a lysate (ii) recovering lysate precipitate containing the polypeptide (iii) resuspending the lysate precipitate in a denaturant-free, non-buffered solubilization solution to produce a solubilization preparation that comprises both sodium hydroxide between about 8 and about 10 mM and the target peptide between about 1 and about 4 mg peptide per ml solubilization solution, wherein the resultant solubilization preparation has a pH of between about 9 and about 11.2; (iv) recovering supernatant from the solubilization preparation containing non-denatured target peptide. Optionally, stabilizing compounds and detergents are employed.