X-ray Absorption Investigation of a Unique Protein Domain Able To Bind both Copper(I) and Copper(II) at Adjacent Sites of the N-Terminus of Haemophilus ducreyi Cu,Zn Superoxide Dismutase

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• 作者：Paola D'Angelo ; Francesca Pacello ; Giordano Mancini ; Olivier Proux ; Jean Louis Hazemann ; Alessandro Desideri ; and Andrea Battistoni
• 刊名：Biochemistry
• 出版年：2005
• 出版时间：October 4, 2005
• 年：2005
• 卷：44
• 期：39
• 页码：13144 - 13150
• 全文大小：93K
• 年卷期：v.44,no.39(October 4, 2005)
• ISSN：1520-4995

文摘

The N-terminal metal binding extension of the Cu,Zn superoxide dismutase from Haemophilusducreyi is constituted by a histidine-rich region followed by a methione-rich sequence which shows highsimilarity with protein motifs involved in the binding of Cu(I). X-ray absorption spectroscopy experimentsselectively carried out with peptides corresponding to the two metal binding regions indicate that bothsequences can bind either Cu(II) or Cu(I). However, competition experiments demonstrate that Cu(II) ispreferred by histidine residues belonging to the first half of the motif, while the methionine-rich regionpreferentially binds Cu(I) via the interaction with three methionine sulfur atoms. Moreover, we haveobserved that the rate of copper transfer from the peptides to the active site of a copper-free form of theCu,Zn superoxide dismutase mutant lacking the N-terminal extension depends on the copper oxidationstate and on the residues involved in metal binding, histidine residues being critically important for theefficient transfer. Differences in the enzyme reactivation rates in the presence of mixtures of the twopeptides when compared to those obtained with the single peptides suggest that the two halves of theN-terminal domain functionally interact during the process of copper transfer, possibly through subtlemodifications of the copper coordination environment.