# Spectroscopic Investigations of Metalloenzyme Mechanisms

> **NIH NIH R35** · UNIVERSITY OF CALIFORNIA AT DAVIS · 2024 · $440,432

## Abstract

Enzymes using metal centers and/or organic radicals play many crucial roles in the fundamental
biochemistry of human health, with deficiencies in their bioassembly or enzymatic functions
associated with various diseases. The R. David Britt laboratory is using advanced spectroscopic
techniques, such as multifrequency electron paramagnetic resonance (EPR), to understand the
assembly and catalytic mechanism of a number of such metal and radical centers. Many
important enzymes involved in multielectron oxidation or reduction reactions employ metal
clusters in their catalysis. The Britt laboratory is studying how such clusters are assembled by
identifying and interrogating assembly intermediates with their spectroscopic methods. For
example, the [Fe-Fe] hydrogenase enzyme uses a complex multinuclear Fe-S “H-cluster”,
containing organometallic Fe-CO and Fe-CN components, to catalyze reversible interconversion
of H2 with protons and electrons. How does nature safely assemble such a center involving
potentially dangerous CO and CN- species? Other experiments are unraveling the biosynthesis
of the complex Fe-S “M-cluster” at the heart of the nitrogenase enzyme, which can incorporate
Mo or V or an additional Fe in its active site. We are studying the biosynthesis of an interesting
Cu(II) containing antibiotic, Fluopsin C. Radical S-adenosylmethione (rSAM) enzymes carry out
many interesting reactions. In one interesting area, we are studying how they transform peptides
into ribosomally-synthesized and post-translationally modified peptide (RiPP) products.
Regulation of metal composition in cells is crucial, and we are examining a number of metal-
binding proteins involved in metal ion sequestration and homeostasis, including a new project
examining lanthanide binding in proteins such as lanmodulin. We are targeting a number of de
novo designed proteins for detailed characterization, and we are starting new collaborations
examining the reactivity of artificial metalloenzymes and DNAzymes. We continue to collaborate
and provide advanced EPR support in a number of interesting metalloenzyme and radical enzyme
arenas, including work to cryotrap, and characterize with high field EPR, the transient oxygen-
generating S4 state of the photosystem II water oxidizing enzyme. And using site directed spin
labeling as a tool, we are probing the dynamics of an all-protein biochemical oscillator that serves
as nature’s simplest circadian clock.

## Key facts

- **NIH application ID:** 10863811
- **Project number:** 5R35GM126961-07
- **Recipient organization:** UNIVERSITY OF CALIFORNIA AT DAVIS
- **Principal Investigator:** R. David Britt
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $440,432
- **Award type:** 5
- **Project period:** 2018-04-01 → 2028-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10863811

## Citation

> US National Institutes of Health, RePORTER application 10863811, Spectroscopic Investigations of Metalloenzyme Mechanisms (5R35GM126961-07). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10863811. Licensed CC0.

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