The de novo protein with grafted biological function: transferring of interferon blast-transforming activity to albebetin.

The de novo protein albebetin has been designed recently to form a predetermined tertiary fold that has not yet been observed in natural proteins. An eight amino acid fragment (131-138) of human interferon alpha(2) carrying the blast-transforming activity of the protein was attached to the N-terminus of albebetin next to its initiatory methionine residue. The gene of chimeric protein was expressed in a wheat germ cell-free translation system and synthesized protein was tested for its compactness and stability. Its ability for receptor binding was also studied. We have shown that albebetin with attached octapeptide is practically as compact as natural proteins of corresponding molecular weight and possesses high stability toward the urea-induced unfolding. It binds murine thymocyte receptor at a high affinity and activates the thymocyte blast transformation efficiently at a concentration of 10(-11) M.