Met-hemocyanin

Figure 12. Comparison of EPR spectra of 1/2-met hemocyanin and T2D laccase in the absence and presence of azide. The T1 copper signal has been subtracted from the T2D laccase data.

Type m proteins 1. Deoxyhemocyanin (7-8 x 10° — 20i) 2. Met-hemocyanine or tyrosinase I/I II/II Proposed structure Cu1 Cu1 N L N u XCu" iL XN Colourless 670 14 925 350 to 600 Cu VCu1 Diamagnetic ESR silent Hydroxy monophenols Oxidizing o-diphenols 02— 2H20 (catalase) Oxygen bonding... 

Figure 101 The absorption spectra of half-met-hemocyanin protein plus added bridging ligands 15 K IT —...

Figure 17. Comparison of the reactivity and magnetism ofdeoxy and met hemocyanin and the laccase type 3 copper site in the T2D derivative.

Figure 18. Comparison of half-met hemocyanin with the half-met type 3 (in T2D) laccase copper sites. A EPR spectra and binding constants of exogenous azide binding. B Spectroscopically effective structural models for exogenous ligand binding to the half-met derivatives and their relation to differences in dioxygen reactivity.

Fig. 25. Absorption spectra (—15 K, pH = 6.3 in 1 1 sucrose glass) and EPR spectra (77 K, v = 9.1 GHz) of the half-met hemocyanin series dotted line for NJ is 7K spectrum (from Ref. 52)...

Fig. 32. EPR spectra68 of met hemocyanin (1-2 mM protein concentration 7 K v = 9.2 GHz, 10 mW power) under the indicated conditions anions in > 5-fold excess at pH = 5.0, 0.1M Ac" buffer sharp signal at g = 4.3 is ubiquitous rhombic iron impurity mononuclear Cu+2 signal at g = 2.1 is due to sites irreversibly damaged by large anion excess dotted lines are simulations with Cu-Cu distance (r) indicated...

Mixed-valence dicopper complexes have been of some interest as models for the spectroscopically informative half-met hemocyanins 156, 157). These complexes are described as Class I if the unpaired electron is localized on one copper ion (i.e., [Cu(I)Cu(II)]) and Class III if it is fully delocalized (i.e., [Cu(1.5)Cu(1.5)]) intermediate situations... 

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