# Synthetic Modeling of Copper Protein Active Sites

> **NIH NIH R01** · WASHINGTON UNIVERSITY · 2020 · $350,750

## Abstract

Project Summary/Abstract
The proposed work will provide detailed understanding of geometries, electronic structures, bonding,
and chemical reaction mechanisms for copper complexes relevant to key postulated intermediates in
copper enzymes. In specific aim 1, the properties and bio-relevant reactivity of [CuO]+ and [CuOOR]2+
complexes will be characrterized in order to evaluate their feasibility as intermediates in oxidation
catalysis by monocopper sites in enzymes. Specific emphasis will be placed on evaluating
mechanistic hypotheses put forth for lytic polysaccharide monooxygenase (LPMO), which is of
particular interest due to its use in biotechnology applications and the very strong (>95 kcal/mol) C-H
bond of its substrate that is attacked. In specific aim 2, a novel synthetic route will be used to access
the first examples of complexes with the [CuIIOCuIII]3+ core, which has been postulated on the basis of
theory to be particularly reactive and thus an attractive structural candidate for the key intermediate in
particulate methane monooxygenase. This route will involve O-O bond cleavage of [CuII(µ-
OOR)CuIII]3+ complexes using continuous irradiation or time-resolved transient spectroscopy methods
in a collaborative effort, and will provide experimental evidence pertinent to the potential involvement
of such species in pMMO and other catalytic systems that attack recalcitrant C-H bonds. In specific
aim 3, the preparation and exploration of the properties and reactivity of novel tricopper-peroxo
[Cu3(O22-)]n+ (n = 2-4) and sulfide-containing [Cu3(µ-S)]n+ (n = 1-4) clusters supported by new
multinucleating ligands are proposed. The studies of the former will test specific structural proposals
for a key intermediate (“PI”) in O2 reduction to H2O by the tricopper active site in the multicopper
oxidases (MCO's). The studies of the latter will aim to evaluate mechanistic hypotheses for the
sulfide-bridged tetracopper CuZ site in the key global nitrogen cycle enzyme nitrous oxide reductase
(N2OR), for which the targeted tricopper clusters will serve as a subunit model. Through these
exploratory synthetic studies, thorough examinations of molecular properties, and detailed kinetic and
mechanistic evaluation of biomimetic reactions, new insights into the fundamental chemistry of
reactive species relevant to putative active site intermediates will be obtained. Ultimately, these
synthetic studies will show what is possible for copper protein active sites in terms of structures,
bonding, reactivity, and reaction pathways, thus providing a fundamental basis for understanding
copper protein structure/function relationships. Such knowledge is critically important in view of the
broad importance of copper-promoted biological reactions and, ultimately, will enable strategies for
manipulation of enzyme function and development of new catalysts.

## Key facts

- **NIH application ID:** 9993922
- **Project number:** 5R01GM047365-29
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** WILLIAM B Tolman
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $350,750
- **Award type:** 5
- **Project period:** 1992-08-01 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9993922

## Citation

> US National Institutes of Health, RePORTER application 9993922, Synthetic Modeling of Copper Protein Active Sites (5R01GM047365-29). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9993922. Licensed CC0.

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