Copper enzymes characteristics

Welch, R. C. W., Rase, H. F. Selectivity Characteristics of a Geometrically Designed Heterogeneous Catalyst. A High Melting Copper-Enzyme Model. Ind. Eng. Chem. Fundamentals 8, 389 (1969). 

A number of copper enzymes have also proved amenable to this type of flow work ascorbate oxidase, for instance, generates the characteristic... 

All of the currently known copper proteins which contain type 1 copper centers are derived from a common ancestor. The various characteristics of the small blue proteins, and the development from copper proteins to copper enzymes and from there to non-catalytic, non-copper proteins are the results of a solely divergent evolution. 

In its biochemical functions, ascorbic acid acts as a regulator in tissue respiration and tends to serve as an antioxidant in vitro by reducing oxidizing chemicals. The effectiveness of ascorbic acid as an antioxidant when added to various processed food products, such as meats, is described in entry on Antioxidants. In plant tissues, the related glutathione system of oxidation and reduction is fairly widely distributed and there is evidence that election transfer reactions involving ascorbic acid are characteristic of animal systems. Peroxidase systems also may involve reactions with ascorbic acid In plants, either of two copper-protein enzymes are commonly involved in the oxidation of ascorbic acid. 

For consistency with the experimental data, an equivalent site model requires that the absorption characteristics of each of the two type 3 copper ions be independent of their state of coupling. For a nonequivalent site model one has to assume that the absorption at 330 nm is entirely caused by the Cu(II) ion with the higher redox potential, so that the observed equilibrium can be assigned to the oxidation-reduction of this site. In both cases we take into account that the addition of four oxidizing equivalents restore the original absorption of the enzyme, and we assume... 

Spectral studies of the native enzyme are difficult to interpret due to simultaneous contributions from all three types of copper. The EPR spectrum (Fig. 38) of native laccase98) shows features attributable to the type 2 (g = 2.237, gx = 2.053, A = 206 x 10-4 cm-1) and type 1 (gz = 2.300, gy = 2.055, g = 2.030, Az = 43 x 10-4 cm-1) coppers. The type 3 site is EPR-non-detectable and diamagnetic (-2 J >550 cm-1)56,57). This site should be compared to the met derivative of hemocyanin and tyrosinase only in the sense that it appears to contain two anti-ferromagnetically coupled copper(II) s lacking an EPR signal. A characteristic Blue band of the type 1 copper is seen in the optical spectrum at 614 nm (c = 5700 M-1 cm-1). The shoulder observed at 330 nm (e 2800 M-1 cm-1) was originally associated with the type 3 copper site, as it reduces with two electrons at... 

Copper is the third most abundant metallic element in the human body, following iron and zinc. It also occurs in all other forms of life and it plays a role in the action of a multitude of enzymes that catalyze a great variety of reactions. There are two cross-cutting ways to classify the copper-containing enzymes (1) According to the structural and spectroscopic characteristics of the copper complex at the active site. (2) According to the function of the enzyme. We shall base discussion on the first of these, with allusions to function as we go along. 

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