De Novo Design of Lanthanide Fingers

Christopher amEnde
University of Delaware

A series of peptides has been synthesized using the 25 amino acid zinc finger motif as a model. The sequence has been modified from the soft Cis2His2 binding residues to a hard Asp2Glu2 binding to allow for lanthanide, instead of zinc, binding. The binding has been analyzed using a several methods. Circular dichroism (CD) was used to monitor the extent of protein folding. The CD data showed characteristic metal bound zinc finger CD spectra upon titration with various lanthanides. Metal binding was also analyzed using luminescence resonance energy transfer (LRET), between tryptophan residues and terbium. In addition, fluorophores have been conjugated to selected amino acids to monitor peptide folding using fluorescence resonance energy transfer (FRET). FRET data gave further evidence of the conformational changes associated with metal binding.