Copper(I)-alkyl sulfide and -cysteine tri-nuclear clusters as models for metallo proteins: a structural density functional analysis.
After having set up the computational methodology for Cu(I)-sulfur systems as models for copper proteins, namely using the simple ligands H(2)S, HS(-), CH(3)SH, and CH(3)S(-), the Cu(I)-Cysteine systems have been investigated: [Cu(I)( S -H(2)Cys) (n) ](+) (H(2)Cys, cysteine, NH(2),SH,COOH) [Cu(I)( S -HCys) (n) ](1-)  (n)  (NH(2),S(-),COOH). Finally, the structures for bi-nuclear [Formula: see text] (Et, CH(2)CH(3)), [Formula: see text] and tri-nuclear [Cu(I)( S -SH)](3), [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] (NH(2),SH,COOH), [Formula: see text] (NH(2),S(-),COOH, and NH(2),SH,COO(-)), as well as [Formula: see text] (NH(2),S(-),COO(-)), were also optimized to mimic the active center for a metallo-chaperone copper transport protein (CopZ). The X-ray structures for the biomolecules were matched fairly well as regards the Cu-S bond distances and Cu…Cu contact distances in the case the model cysteine S atom is deprotonated. Upon protonation of ligand S atoms, the conformation of clusters is altered and might bring about the di- and tri-nuclear core breakage. These findings suggest that subtle protonation/deprotonation steps, i.e. small and/or local pH changes play a significant role for copper transport processes.
Department of Chemistry, University of Siena, Via Aldo Moro 2, I-53100, Siena, Italy.
Gabriella
G
Tamasi
Stefano
S
Mangani
Renzo
R
Cini
D003198:Computer Simulation; D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper; D003545:Cysteine / Q000737:chemistry*; D008667:Metalloproteins / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D018716:Molecular Mimicry; D011789:Quantum Theory; D013440:Sulfides / Q000737:chemistry*; D013816:Thermodynamics
D056831:Coordination Complexes; D008667:Metalloproteins; D013440:Sulfides; D003300:Copper; D003545:Cysteine