Laccase peroxy intermediate

Figure 22. Comparison of oxygen intermediates. A Electronic absorption spectra of the peroxy-intermediate in laccase versus oxyhemocyanin and oxytyrosinase. B Proposed structural differences between peroxide binding in oxyhemocyanin and oxytyrosinase relative to the end-on bound hydroperoxide intermediate at the trinuclear copper cluster in laccase.

The catalytic cycle of multicopper oxidases is very complex because the four redox active Cu centers need to store reducing equivalents coming from four substrate molecules and transfer the electrons to dioxygen. From spectroscopic studies and fast kinetic experiments carried out on laccase it has been shown that reaction of fully reduced enzyme with O2 produces two intermediates, labeled as peroxy intermediate and native intermediate (Scheme 3). The peroxy intermediate has been trapped in a derivative of... 

Sundaram UM, Zhang HH, Hedman B, Hodgson KO, Solomon EL Spectroscopic investigation of peroxide binding to the trinuclear copper cluster site in laccase correlation with the peroxy-level intermediate and relevance to catalysis. J Am Chem Soc 1997 119 12525-12540. 

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