# Biosynthetic Models of Heteronuclear Metalloenzymes in Multi-electron Processes

> **NIH NIH R01** · UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN · 2020 · $292,124

## Abstract

Project Summary/Abstract
 The overall goal of the project is to achieve holistic understanding of structure and
function of heteronuclear metalloenzymes involved in multi-electron redox processes,
which are more difficult to study than homonuclear enzymes, and to address important
scientific issues in the fields of respiration and the global nitrogen and sulfur cycles.
Specifically, we seek to investigate why a heme-nonheme Fe center in nitric oxide
reductase (NOR) is effective at 2e- reduction of NO, allowing N-N bond formation, whereas
a heme-Cu center in heme-Cu oxidase (HCO) is proficient at 4e- reduction of O2, enabling
O-O bond cleavage, while both a different heme-Cu center in sulfite reductase from W.
succinogenes (SiRA) and a heme-Fe4S4 center in assimilatory sulfite reductases (SiR) are
efficient at 6e- reduction of sulfite, promoting S-O bond cleavage. To achieve this goal, the
proposal is based on a scientific premise that developing a novel biosynthetic approach
using stable, easy-to-produce, and well-characterized heme proteins as scaffolds for
making structural and functional models of HCO, NOR, SiRA and SiR can overcome
critical methodological barriers to progress in the field. We will use the biosynthetic models
to 1) Understand how a heme-Cu center can exhibit either HCO or SiR activity, 2) elucidate
structural features responsible for catalytic activity and substrate binding affinity of SiR, 3)
clarify the roles of Tyr in HCO and SiR activities, and 4) investigate the roles of heme
cofactors in HCO, NOR and SiR activities. To ensure scientific rigor, we will use activity
as guidance for our project design and spectroscopic, crystallographic and computational
techniques to characterize our models.
 Achieving the above goals will result in deeper understanding of the structure and
function of HCO, NOR, SiRA and SiR that may be very difficult to achieve by studying the
native enzymes alone. The ability to place different heteronuclear metal centers into the
same protein scaffold offers insight into similarities and differences between the four
heteronuclear metalloenzymes. In doing so, the project will advance the knowledge of
metalloprotein structure, function, and design in general, as the guiding principles obtained
from these studies will be applicable to a broad range of metalloenzymes important for
human health.

## Key facts

- **NIH application ID:** 9903341
- **Project number:** 5R01GM062211-18
- **Recipient organization:** UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
- **Principal Investigator:** Yi Lu
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $292,124
- **Award type:** 5
- **Project period:** 2001-04-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9903341

## Citation

> US National Institutes of Health, RePORTER application 9903341, Biosynthetic Models of Heteronuclear Metalloenzymes in Multi-electron Processes (5R01GM062211-18). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9903341. Licensed CC0.

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