Enzymatic Nitrogen Incorporation Using Hydroxylamine
Shilong Gao1, Anuvab Das1, Edwin Alfonzo1
1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Journal of the American Chemical Society
|September 6, 2023
Summary
Researchers engineered a heme enzyme to activate hydroxylamine for sustainable nitrene transfer reactions, enabling efficient amine synthesis with water as the only byproduct.
Area of Science:
- Biocatalysis
- Organic Chemistry
- Enzyme Engineering
Background:
- Hydroxylamine-derived reagents are used for nitrene transfer reactions but generate waste.
- Activating hydroxylamine (NH2OH) offers a sustainable route to amine synthesis with water as the sole byproduct.
- Enzymatic use of hydroxylamine for nitrogen incorporation in biosynthesis is currently unknown.
Purpose of the Study:
- To engineer a heme enzyme capable of utilizing hydroxylamine for nitrene transfer.
- To develop a sustainable method for amine synthesis using inexpensive commodity chemicals.
- To explore the potential for discovering natural enzymes involved in hydroxylamine-based amination.
Main Methods:
- Directed evolution of *Pyrobaculum arsenaticum* protoglobin.
- Utilizing hydroxylammonium chloride as the hydroxylamine source.
- Mechanistic studies to elucidate the reaction pathway.
Main Results:
- An engineered heme enzyme efficiently performs nitrene transfer using hydroxylammonium chloride.
- The enzyme catalyzes benzylic C-H primary amination and styrene aminohydroxylation.
- Mechanistic studies revealed a stepwise radical pathway initiated by hydrogen atom transfer.
Conclusions:
- Engineered heme enzymes can utilize hydroxylamine for nitrene transfer, offering a sustainable alternative to traditional reagents.
- This work expands the repertoire of nitrene transferases and suggests potential for discovering novel natural enzymes.
- The findings pave the way for greener synthesis of nitrogen-containing compounds.
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