Active site-specific reconstituted copper (II) horse liver alcohol dehydrogenase: a biological model for type 1 Cu2+ and its changes upon ligand binding and conformational transitions

Maret, W.; Dietrich, H.; Ruf, H.H.; Zeppezauer, M.

Journal of Inorganic Biochemistry 12(3): 241-252


ISSN/ISBN: 0162-0134
PMID: 6247444
DOI: 10.1016/s0162-0134(00)80205-6
Accession: 042167298

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Insertion of Cu2+ ions into horse liver alcohol dehydrogenase depleted of its catalytic Zn2+ ions creates an artificial blue copper center similar to that of plastocyanin and similar copper proteins. The esr spectrum of a frozen solution and the optical spectra at 296 and 77 K are reported, together with the corresponding data for binary and ternary complexes with NAD+ and pyrazole. The binary complex of the cupric enzyme with pyrazole establishes a novel type of copper proteins having the optical characteristics of Type 1 and the esr parameters of Type 2 Cu2+. Ternary complex formation with NAD+ converts the Cu2+ ion to a Type 1 center. By an intramolecular redox reaction the cuprous enzyme is formed from the cupric enzyme. Whereas the activity of the cupric alcohol dehydrogenase is difficult to assess (0.5%-1% that of the native enzyme), the cuprous enzyme is distinctly active (8% of the native enzyme). The implications of these findings are discussed in view of the coordination of the metal in native copper proteins.