Carboxy-terminal truncated rhuIFN-gamma with a substitution of Gln133 or Ser132 to leucine leads to higher biological activity than in the wild type

The biological function of the 20 C-terminal amino acids of human Interferon-gamma (IFN-gamma) was examined. Six truncated IFN-gamma analogues were produced by recombinant DNA technique and expressed in Escherichia coli. In four of these constructions the C-terminal amino acid is replaced by leucine. The antiviral activities of the variants lacking 14 or more amino acids are less than 2 per cent of the control. The variant C-10 Leu exhibits a fourfold higher antiviral activity compared to complete IFN-gamma. CD analysis reveals no significant differences for the variants, but C-10 Leu shows a higher temperature stability.