# Contribution of Ligand Sets to Oxygen Activation in Iron-dependent Biocatalysts

> **NIH NIH R35** · UNIVERSITY OF GEORGIA · 2022 · $377,500

## Abstract

Project Summary
The central theme of this project is dioxygen activation for C-H/C-C bond functionalization, which is fundamental for
aerobic life. Molecular oxygen is a powerful oxidant, but the reaction with ground-state singlet molecules is kinetically
unfavorable due to the spin-forbidden nature. To harness the oxidizing power of oxygen and circumvent the unregulated
production of reactive oxidative species, metalloenzymes are frequently employed by aerobic organisms to activate oxygen
and manipulate biomolecules. Heme and non-heme iron enzymes are two of the most ubiquitous and potent natural catalysts.
Representative systems have been well characterized with near-complete mechanistic delineation. However, catalytic
pathways of iron-dependent oxygenases with less common ligand sets lack description, and studies emphasizing an
individual system do not often consider the intrinsic differences between heme and non-heme coordination. A holistic
picture to systematically compare these two systems regarding oxygen activation and reactivity is deficient in the field. This
project desires to fill the knowledge gap by investigating how the ligand sets contribute to reaction outcomes and why a
particular system exploits one coordination over the other for a specific reaction. An apparent challenge of direct comparison
is the massive variability between systems: the selection of ligand donors, active site environment, substrate-binding mode,
and overall protein scaffold. To simplify the coordination environment for an unbiased comparison, two unique
multifunctional oxygenases are chosen, each with an iron center ligated only by nitrogen-donors. One is a His-ligated heme-
dependent enzyme responsible for pyrrolnitrin production, promoting remarkable rearrangement of a tryptophan derivative.
The other is a non-heme iron-dependent enzyme crucial for the visual cycle, which catalyzes oxidative alkene cleavage and
isomerization using a 4-His ligated ferrous iron. The catalytic mechanisms and structure-function correlations of both
enzymes are poorly understood and the ligand sets are rarely found to mediate oxygenation reactions. Over the five-year
funding period, we will comparatively investigate the heme and non-heme systems to decode how the atypical ligand sets
promote the unusual biotransformations and how oxygen activation is tuned by the presence or absence of a porphyrin ring.
Ultimately, the proposed research will leverage the understanding of iron-oxygen chemistry, inspire the design of
biomimetic complexes and engineered biocatalysts, and advance the potential for biomedical treatments for fungal infection
and impaired vision.

## Key facts

- **NIH application ID:** 10500650
- **Project number:** 1R35GM147510-01
- **Recipient organization:** UNIVERSITY OF GEORGIA
- **Principal Investigator:** Yifan Wang
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $377,500
- **Award type:** 1
- **Project period:** 2022-08-01 → 2027-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10500650

## Citation

> US National Institutes of Health, RePORTER application 10500650, Contribution of Ligand Sets to Oxygen Activation in Iron-dependent Biocatalysts (1R35GM147510-01). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10500650. Licensed CC0.

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