Abstract: Novel peptide having a sequence according to SEQ. ID. No. 1, SEQ. ID. No. 2 and/or SEQ. ID. No. 3 are disclosed and also polypeptide scaffold consisting of a four helix bundle formed of two dimerized helix-loop-helix motifs, said helix-loop-helix motifs having sequences according to SEQ. ID. No. 1, SEQ. ID. No. 2 and/or SEQ. ID. No. 3 which may comprise a fluorescent probe at the side chain of Lys15 and a ligand with affinity for a target molecule at the side chain of Lys8 or Lys34. Also disclosed are polypeptide scaffolds for use in biosensing applications with or without the polypeptide scaffold anchored to a solid surface.