title: Chemical synthesis and evaluation of a backbone-cyclized minimized 2-helix Z-domain.
abstract: The Z-molecule is a small, engineered IgG-binding affinity protein derived from the immunoglobulin-binding domain B of Staphylococcus aureus protein A. The Z-domain consists of 58 amino acids forming a well-defined antiparallel three-helix structure. Two of the three helices are involved in ligand binding, whereas the third helix provides structural support to the three-helix bundle. The small size and the stable three-helix structure are two attractive properties comprised in the Z-domain, but a further reduction in size of the protein is valuable for several reasons. Reduction in size facilitates synthetic production of any protein-based molecule, which is beneficial from an economical viewpoint. In addition, a smaller protein is easier to manipulate through chemical modifications. By omitting the third stabilizing helix from the Z-domain and joining the N- and C-termini by a native peptide bond, the affinity protein obtains the advantageous properties of a smaller scaffold and in addition becomes resistant to exoproteases. We here demonstrate the synthesis and evaluation of a novel cyclic two-helix Z-domain. The molecule has retained affinity for its target protein, is resistant to heat treatment, and lacks both N- and C-termini.
authors.affiliation: Royal Institute of Technology (KTH), School of Biotechnology, Division of Molecular Biotechnology, Stockholm, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Järver
authors.forename: Cecilia
authors.initials: C
authors.lastname: Mikaelsson
authors.forename: Amelie Eriksson
authors.initials: AE
authors.lastname: Karlström
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D006801:Humans; D055767:Immobilized Proteins / Q000737:chemistry; D007074:Immunoglobulin G / Q000737:chemistry; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis* / Q000737:chemistry; D010456:Peptides, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013205:Staphylococcal Protein A / Q000737:chemistry*; D020349:Surface Plasmon Resonance
chemical_list: D055767:Immobilized Proteins; D007074:Immunoglobulin G; D010446:Peptide Fragments; D010456:Peptides, Cyclic; D013205:Staphylococcal Protein A