CONCENTRATED COMPOSITIONS OF PROTEINS, THEIR PREPARATION AND USE THEREOF

The invention relates to a method for producing a composition comprising reversible protein complexes (RPCs), the method comprising the steps of contacting a protein and a complexing agent in a buffer solution, wherein the complexing agent is dextran sulphate or chondroitin sulphate, and wherein the protein and the complexing agent have opposite net charges when comprised in the buffer solution; formation of RPCs between the protein and the complexing agent in the buffer solution; and obtaining a suspension comprising the RPCs. Provided herein are also compositions, including pharmaceutical compositions/ formulations comprising the reversible protein complexes (RPCs) of the invention, in particular as obtained by the method provided herein.