Abstract: The present invention generally relates to the provision of means and methods for preparing protein compositions. The invention provides a method comprising the steps of (i) contacting a starting composition comprising a protein with a hydrolase inhibitor, wherein the hydrolase inhibitor is immobilized on a solid carrier; (ii) recovering a composition comprising the protein. Furthermore, the invention relates to a method for preparing a protein formulation comprising the steps of (i) contacting a starting composition comprising a protein with a hydrolase inhibitor, wherein the hydrolase inhibitor is immobilized on a solid carrier; (ii) recovering a composition comprising the protein, wherein the method for preparing the protein formulation further comprises adding a surfactant, preferably a fatty acid ester, to the composition comprising the protein.

Abstract: The invention provides the means to enhance in E. coli-based expression systems the formation of fusion polypeptides containing as an N-terminal tag a biotinylation polypeptide. By way of specifically exchanging in the nucleic acid sequence encoding the biotinylation polypeptide nucleotides at 11 discrete positions enhances the formation of the total fusion polypeptide by at least 40%.

Abstract: An enzyme selected from penicillin-G amidase, glutaryl-7-ACA acylase and D-amino acid oxidase is immobilized by covalent bonding on an aminofunctional organosiloxane polymer carrier to provide an immobilized enzyme having a specific volume activity of at least 100 U/g wet carrier. Preferably, the carrier has an average diameter or 0.01 to 3 mm and is essentially spherical. Covalent bonding is accomplished by activating amino groups on the carrier with a dialdehyde and reacting the activated groups with reactive groups on the enzyme. An amount of enzyme is immobilized to provide a weight ratio of enzyme to carrier of 1 to 300 mg protein per g wet carrier.