# Mechanisms of Catalysis and Cofactor Biosynthesis of Redox Enzymes with Unusual Cofactors

> **NIH NIH R35** · UNIVERSITY OF CENTRAL FLORIDA · 2021 · $401,222

## Abstract

This research program focuses on the characterization of redox enzymes with unusual
cofactors, and their interactions with other electron transfer (ET) proteins. This includes
enzymes that do not contain exogenous cofactors, but instead possess “protein-derived
cofactors” that are formed by multiple irreversible post-translational modifications of amino acid
residues. This research has made major contributions to at least three areas of broad biological
and biomedical significance: elucidation of mechanisms of biological ET; characterization of
mechanisms of biosynthesis of protein-derived cofactors and their catalytic properties; and
discovery of novel mechanisms of heme function and oxygen activation. The future goals
include characterization of three novel classes of redox enzymes that we have recently
identified. Lod-A like proteins possess a cysteine tryptophylquinone (CTQ) cofactor derived from
specific cysteine and tryptophan residues. These are unusual as they are the first enzymes with
tryptophylquinone cofactors that function as oxidases rather than dehydrogenases. They are
also the first amino acid oxidases described that uses a cofactor other than a flavin for catalysis.
LodB-like proteins are flavoenzymes that catalyze the post-translational modifications required
for CTQ biosynthesis on a precursor LodA-like protein. These reactions must be performed by
“remote catalysis” that involves long-range ET, since the residues that are modified reside within
the protein and are not surface exposed. As such, the mechanism of this process must be novel
because no such reactions have been described that are catalyzed by a flavoenzyme,
especially by remote catalysis. Rv2633c is a protein from Mycobacterium tuberculosis that is
upregulated in response to the host defense during infection. It possesses two non-heme irons
that are predicted from sequence to form an oxo-bridged hemerythrin-like site. We showed that
this is the first hemerythrin-like protein to function as a catalase, and is the first example of a
catalase with a non-heme di-iron cofactor. The results of these studies will further our
understanding of the range and mechanisms of reactions that can be catalyzed by enzymes,
particularly those involving oxygen reactivity and free radical intermediates. Understanding how
enzymes control these reactive species during catalysis while minimizing oxidative damage will
provide insights into how to mitigate the consequences of oxidative stress. This will also expand
or current views about protein evolution and protein structure-function relationships, and provide
insights for protein engineering strategies to introduce new functional groups into proteins.

## Key facts

- **NIH application ID:** 10071169
- **Project number:** 5R35GM130173-03
- **Recipient organization:** UNIVERSITY OF CENTRAL FLORIDA
- **Principal Investigator:** VICTOR L DAVIDSON
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $401,222
- **Award type:** 5
- **Project period:** 2019-01-01 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10071169

## Citation

> US National Institutes of Health, RePORTER application 10071169, Mechanisms of Catalysis and Cofactor Biosynthesis of Redox Enzymes with Unusual Cofactors (5R35GM130173-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10071169. Licensed CC0.

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