Purification of transforming growth factor type e

Abstract

Transforming growth factor type e (TGFe) is a heat‐ and acid‐stable polypeptide with an apparent molecular weight of 22,000, which stimulates the proliferation of certain epithelial and mesenchymal cells in monolayer and soft agar. TGFe has been purified to homogeneity. Initial acid‐ethanol extraction of bovine kidney was followed by batch ion‐exchange chromatography utilizing Bio Rex 70 resin. The activity eluted from the Bio Rex 70 resin was concentrated and diafiltered using an Amicon concentrator equipped with an SIY10 spiral membrane, then was further purified by Bio‐Gel P‐60 molecular sieve chromatography. Active fractions from molecular sieve chromatography were pooled and purified by heparin‐Sepharose affinity chromatography, followed by reverse‐phase high‐performance liquid chromatography using a microbore C‐8 column. The final purification step involved electroelution of TGFe separated by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). Purity of TGFe was assessed to be greater than 90%.