Efficient production of human tumour necrosis factor in Escherichia coli

Human tumour necrosis factor (TNF) cDNA was isolated from a cDNA library prepared using TNF mRNA from human alveolar macrophages. Using the cDNA, various expression plasmids were constructed and their TNF producibility was examined in Escherichia coli. The best transformants produced a TNF polypeptide in a yield of about 20% of cellular proteins. The purified TNF polypeptide was lacking a methionine residue at the N-terminus, and possessed the expected physical and chemical properties and the biological activities characteristic of TNF.