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 toform a predetermined tertiary fold that has not yet been observedin natural proteins. An eight amino acid fragment (131–138)of human interferon ₂ carrying the blasttransforming activityof the protein was attached to the N-terminus of albebetin nextto its initiatory methionine residue. The gene of chimeric proteinwas expressed in a wheat germ cell-free translation system andsynthesized protein was tested for its compactness and stability.Its ability for receptor binding was also studied. We have shownthat albebetin with attached octapeptide is practically as compactas natural proteins of corresponding molecular weight and possesseshigh stability toward the urea-induced unfolding. It binds murinethymocyte receptor at a high affinity and activates the thymocyteblast transformation efficiently at a concentration of 10^-11M.