Human recombinant tumor necrosis factor alpha was purified in a single
step to about 95% purity from Escherichia coli lysate by chromatograp
hy on hydroxyapatite. The last traces of contaminants were removed by
fast protein liquid chromatography on a Mono Q column. The final produ
ct was found to be pure by gel electrophoresis with silver staining. A
molecular mass of approximately 17 000 and a specific activity of 4.3
. 10(6) U/mg after a single purification step were found.