METHOD FOR PRODUCING PROTEIN BY PRECIPITATION

The present invention provides a method for producing a target protein in the form of a fusion protein at a high recovery ratio. The present invention relates to a method for producing a fusion protein made of a protein having a self-assembly capability and a target protein comprising the following steps (1) to (4): (1) preparing a solution containing the fusion protein; (2) adjusting a pH of the solution obtained in step (1) to such a pH that a recovery ratio calculated according to the following equation is 10% or more, where the recovery ratio (%)=[an amount of the fusion protein in a solution obtained in step (4)/{the amount of the fusion protein in the solution obtained in step (4)+an amount of the fusion protein in a solution after solid separation in step (3)}]100; (3) separating a solid from the solution obtained in step (2); and (4) dissolving the solid separated in step (3) into a solution having a pH of 12 or below but higher than the pH of the solution obtained in step (2) by 0.1 or more.