Interaction of Cu2+ with His-Val-His and of Zn2+ with His-Val-Gly-Asp, two peptides surrounding metal ions in Cu,Zn-superoxide dismutase enzyme

 
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Interaction of Cu2+ with His-Val-His and of Zn2+ with His-Val-Gly-Asp, two peptides surrounding metal ions in Cu,Zn-superoxide dismutase enzyme (EN)

Myari, A. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Myari, A. (EN)

His-Val-His and His-Val-Gly-Asp are two naturally occuring peptide sequences, present at the active site of Cu,Zn-superoxide dismutase (Cu,Zn-SOD). The interactions of His-Val-His=A (copper binding site) with Cu(II) and of His-Val-Gly-Asp=B (zinc binding site) with Zn(II) have been studied by using both potentiometric and spectroscopic methods (visible, EPR, NMR). The stoichiometry, stability constants and solution structure of the complexes formed have been determined. The binding modes of the species [CuAH](2+) and [CuA](+) were characterized by histamine type of coordination. [CuA](+) is further stabilized by the formation of a macrochelate with the involvement of the imidazole of the C-terminal histidine. The existence of macrochelate results in a slight distortion of the coordination geometry providing good base for the development of enzyme models. The enhanced stability of the macrochelate suppresses the formation of bis-complexes as well as the amide deprotonation. This process, however, takes place at higher pH resulting in the formation of the 4 N- coordinated [NH2,N-,N-,N(im)] species [CuAH(2-)](-). On the other hand, in the case of the Zn(Il)-His-Val-Gly-Asp system, coordination takes place at the terminal carboxylate in species [ZnBH2](2+). Monodentate binding occurs via the N-terminal imidazole in [ZnBH](+) while histamine type of coordination is possible in [ZnB], [ZnB2H](-) and [ZnB2](2-) species. Amide deprotonation does not take place in the case of Zn2+, hydroxo-complexes are formed instead. (C) 2001 Elsevier Science B.V. All rights reserved. (EN)

cu2+ (EN)

Πανεπιστήμιο Ιωαννίνων (EL)
University of Ioannina (EN)

J Inorg Biochem (EN)

Αγγλική γλώσσα

2001

<Go to ISI>://000170339900003

Elsevier (EN)



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