title: Probing the role of the backbone carbonyl interaction with the CuAcenter in azurin by replacing the peptide bond with an ester linkage.
abstract: The role of a backbone carbonyl interaction with an engineered CuAcenter in azurin was investigated by developing a method of synthesis and incorporation of a depsipeptide where one of the amide bonds in azurin is replaced by an ester bond using expressed protein ligation. Studies by electronic absorption and electron paramagnetic resonance spectroscopic techniques indicate that, while the substitution does not significantly alter the geometry of the site, it weakens the axial interaction to the CuAcenter and strengthens the Cu-Cu bond, as evidenced by the blue shift of the near-IR absorption that has been assigned to the Cu-Cu ψ → ψ* transition. Interestingly, the changes in the electronic structure from the replacement did not result in a change in the reduction potential of the CuAcenter, suggesting that the diamond core structure of Cu2SCys2is resistant to variations in axial interactions.
authors.affiliation: Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue Urbana, IL 61801, USA. vddonk@illinois.edu yi-lu@illinois.edu.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Clark
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue Urbana, IL 61801, USA.
authors.forename: Shiliang
authors.initials: S
authors.lastname: Tian
authors.affiliation: Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue Urbana, IL 61801, USA. vddonk@illinois.edu yi-lu@illinois.edu and Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue Urbana, IL 61801, USA.
authors.forename: Wilfred A
authors.initials: WA
authors.lastname: van der Donk
authors.affiliation: Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue Urbana, IL 61801, USA. vddonk@illinois.edu yi-lu@illinois.edu and Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue Urbana, IL 61801, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Lu
mesh_terms: D001400:Azurin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004952:Esters / Q000737:chemistry*; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D015202:Protein Engineering
chemical_list: D004952:Esters; D010455:Peptides; D001400:Azurin