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Title: Simplest Monodentate Imidazole Stabilization of the oxy‐Tyrosinase Cu 2 O 2 Core: Phenolate Hydroxylation through a Cu III Intermediate

Journal Article · · Angewandte Chemie (International Edition)
 [1];  [1];  [1];  [2];  [1]
  1. Department of Chemistry Stanford University Stanford CA 94305 USA
  2. Department Chemistry and Biochemistry California State University Chico CA 95929 USA
+ Show Author Affiliations

Abstract Tyrosinases are ubiquitous binuclear copper enzymes that oxygenate to Cu II 2 O 2 cores bonded by three histidine Nτ‐imidazoles per Cu center. Synthetic monodentate imidazole‐bonded Cu II 2 O 2 species self‐assemble in a near quantitative manner at −125 °C, but Nπ‐ligation has been required. Herein, we disclose the syntheses and reactivity of three Nτ‐imidazole bonded Cu II 2 O 2 species at solution temperatures of −145 °C, which was achieved using a eutectic mixture of THF and 2‐MeTHF. The addition of anionic phenolates affords a Cu III 2 O 2 species, where the bonded phenolates hydroxylate to catecholates in high yields. Similar Cu III 2 O 2 intermediates are not observed using Nπ‐bonded Cu II 2 O 2 species, hinting that Nτ‐imidazole ligation, conserved in all characterized Ty, has functional advantage beyond active‐site flexibility. Substrate accessibility to the oxygenated Cu 2 O 2 core and stabilization of a high oxidation state of the copper centers are suggested from these minimalistic models.

Sponsoring Organization:
USDOE
Grant/Contract Number:
AC02-76SF00515
OSTI ID:
1400775
Journal Information:
Angewandte Chemie (International Edition), Journal Name: Angewandte Chemie (International Edition) Journal Issue: 35 Vol. 55; ISSN 1433-7851
Publisher:
Wiley Blackwell (John Wiley & Sons)Copyright Statement
Country of Publication:
Germany
Language:
English

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