# Redox enzymes - tuning and design

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2020 · $279,124

## Abstract

Project Summary/Abstract
Enzymatic redox catalysis, imperative to all organisms, is a showcase of nature's mastery in tuning the activity and
selectivity at the electronic level. The reduction potential, E0, of the metal performing the redox transformation is
precisely controlled beyond the primary coordination sphere through the microenvironment of the metal in the
protein. Interactions of consequence for the physiologically relevant modulations of E0 are often weak; they include
hydrogen bonds, hydrophobic contacts, and long- to intermediate-range electrostatics. It is a challenge to study the
impact of these individual factors on metalloenzymatic redox processes, and even more so to design metalloproteins
that would perform selective redox catalysis. We propose an approach that allows elaboration of the individual
factors that govern redox properties of metalloproteins en route to the design artificial Co and Mn metalloenzymes
with selective oxygen reduction or oxidative reactivity. We propose metalloprotein constructs that combine synthetic
redox active complexes of Co and Mn with salen ligands, and the protein streptavidin (Sav) to which biotinylated
organometallic complexes will be attached. In these systems, the intermediate-range electrostatics will be controlled
largely within the organometallic complex that has a unique feature, a secondary metal binding site containing a
redox innocent metal ion exerting an electric field on the active cation. Electrochemistry and reactivity of these
complexes will be measured and computed. The protein matrix of Sav will be used for incorporating other weak
interactions in the microenvironment of the metal, such as H-bonds and hydrophobic contacts, through mutagenesis.
Mixed quantum mechanical and quantum-classical simulations will guide the choice for mutations to consider for
the desired redox activity. Importantly, while in natural metalloenzymes all the weak factors influencing E0 also
influence the protein structure and couple to each other, in the proposed systems, they are decoupled to the extent
possible, and thus more amendable to studying and strategic modifications. Broadly, this research will allow learning
how redox chemistry is controlled in nature, and how to approach the design of redox enzymes. Our target catalytic
reactions of oxygen reduction and aerobic substrate oxidation are of interest to both natural enzymology and the
broader field of catalysis, and understanding these reactions is essential for realizing how aerobic metabolism
efficiently utilizes oxygen while avoiding the formation deleterious concentrations of ROS.

## Key facts

- **NIH application ID:** 10001577
- **Project number:** 5R01GM134047-02
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **Principal Investigator:** ANASTASSIA N ALEXANDROVA
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $279,124
- **Award type:** 5
- **Project period:** 2019-09-01 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10001577

## Citation

> US National Institutes of Health, RePORTER application 10001577, Redox enzymes - tuning and design (5R01GM134047-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10001577. Licensed CC0.

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