COLLECTION OF PURIFIED GROWTH HORMONE FROM MICROBE TREATED BY GENIC ENGINEERING

This invention concerns a method for recovering a purified eucaryotic growth hormone or an analog thereof from a bacterial cell in which the growth hormone or analog has been produced by means of expression of a DNA sequence encoding the hormone or analog. The method involves the following steps: (a) disrupting the cell wall of the bacterial cell or fragments thereof to produce a lysate; (b) separating a precipitate containing particulate and insoluble material from the lysate; (c) preparing suspension of the separated precipitate in an appropriate buffer solution; (d) treating the suspension to effect contact between liquid and solids; (e) separating partially or completely precipitated material from the liquid-solids contacted suspension; (f) solubilizing the separated precipitate in a sufficient amount of water and adjusting the pH to a suitable alkaline pH to form a solution; (g) separating the solubilized hormone or analog from other cellular components by ultrafiltration under suitable conditions to produce an ultrafiltrate containing the hormone or analog and a retentate, and (h) treating the solubilized hormone or analog so as to concentrate the hormone or analog and thereby recover purified hormone or analog. Separations may be effected by ultrafiltration or centrifugation. Sonication as well as the ultrafiltration in step (i) may be repeated. Additionally, most of the process steps may be performed in a continuous flow and may be automated. Suitable hormone-producing bacterial cells for use in this invention include genetically modified strains of Escherichia coli. Growth hormones which can be recovered and purified using this invention include bovine, porcine, chicken, and human growth hormones, and analogs thereof.