The deoxygenated form [Cu(I)Cu(I)] of molluscan hemocyanin exhibits a catalase-like activity. The initial Formation of the met-derivative [Cu(II)Cu(II)] is followed by reaction of a second molecule of hydrogen peroxide, leading to oxy-hemocyanin. Sodium azide, a ligand that is also able to coordinate to the binuclear cupric site of met-hemocyanin, shows competitive inhibition of the regeneration reaction by hydrogen peroxide. Therefore, in the presence of an excess of azide the reduction of met-hemocyanin by hydrogen peroxide is prevented and the met-hemocyanin azide complex becomes the main reaction product. After removal of excess reactants, the derivative obtained exhibits the characteristic features of met-hemocyanin. The preparation of this derivative by the present method requires a shorter time and is carried out under milder chemical conditions than those used in other methods previously reported in the literature. Furthermore, this new method is based on trapping of a reaction intermediate and not on the chemical modification of the protein after the labilization of the active site. (C) 1998 Elsevier Science Inc: All rights reserved.

Isolation of the met-derivative intermediate in the catalase-like activity of deoxygenated Octopus vulgaris hemocyanin / T. Zlateva, L. Santagostini, L. Bubacco, L. Casella, B. Salvato, M. Beltramini. - In: JOURNAL OF INORGANIC BIOCHEMISTRY. - ISSN 0162-0134. - 72:3-4(1998), pp. 211-215. [10.1016/S0162-0134(98)10082-X]

Isolation of the met-derivative intermediate in the catalase-like activity of deoxygenated Octopus vulgaris hemocyanin

L. Santagostini
Secondo
;
1998

Abstract

The deoxygenated form [Cu(I)Cu(I)] of molluscan hemocyanin exhibits a catalase-like activity. The initial Formation of the met-derivative [Cu(II)Cu(II)] is followed by reaction of a second molecule of hydrogen peroxide, leading to oxy-hemocyanin. Sodium azide, a ligand that is also able to coordinate to the binuclear cupric site of met-hemocyanin, shows competitive inhibition of the regeneration reaction by hydrogen peroxide. Therefore, in the presence of an excess of azide the reduction of met-hemocyanin by hydrogen peroxide is prevented and the met-hemocyanin azide complex becomes the main reaction product. After removal of excess reactants, the derivative obtained exhibits the characteristic features of met-hemocyanin. The preparation of this derivative by the present method requires a shorter time and is carried out under milder chemical conditions than those used in other methods previously reported in the literature. Furthermore, this new method is based on trapping of a reaction intermediate and not on the chemical modification of the protein after the labilization of the active site. (C) 1998 Elsevier Science Inc: All rights reserved.
hemocyanin ; copper active site ; met-hemocyanin ; hydrogen peroxide ; azide
Settore CHIM/03 - Chimica Generale e Inorganica
Settore BIO/10 - Biochimica
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/196707
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