About

Xiongyi Huang grew up in Guilin, China, and received his B.S. Degree in Chemistry in 2010 from the University of Science and Technology of China (USTC), where he worked on computational organic chemistry. He completed his PhD at Princeton University under Prof. John T. Groves, developing Mn-catalyzed biomimetic C–H functionalization methods and collaborating on radiolabeling chemistry for PET applications. Following his PhD, he worked with Prof. Frances Arnold at Caltech as an NIH NRSA Postdoctoral Fellow and later as an NIH Pathway to Independence Postdoctoral Fellow, where he used directed evolution to engineer enzymes for novel reactions, including the first enzymatic system for carbon−boron bond formation and biocatalysts for organofluorine synthesis. In September 2019, Xiongyi Huang joined Johns Hopkins University as an Assistant Professor in the Department of Chemistry. His research focuses on leveraging the diversity of metalloenzymes to address challenges in chemistry and biology, employing interdisciplinary approaches such as organic synthesis, chemical biology, protein engineering, biochemical analysis, and computational modeling to reprogram metalloenzymes for new catalytic functions.

Research topics

• Combinatorial chemistry
• Stereochemistry
• Chemistry
• Organic chemistry
• Materials science
• Biochemistry
• Biology

Selected publications

• Reprogramming nonheme iron enzymes for abiotic alkene trifluoromethylazidation

  Methods in enzymology on CD-ROM/Methods in enzymology · 2025-01-01

  book-chapterOpen accessSenior authorCorresponding
  PublisherOA PDFDOI

• A metallophotoredox strategy for biocatalytic radical C–N3 and C–SCN bond formation

  Methods in enzymology on CD-ROM/Methods in enzymology · 2025-01-01

  book-chapterSenior authorCorresponding
  PublisherDOI

• Biocatalytic Olefin Difunctionalization for Synthesis of Chiral 2‐Azidoamines Using Nonheme Iron Enzymes

  Angewandte Chemie · 2025-08-10

  articleSenior author

  Abstract Alkene difunctionalization represents an important category of reactions in organic synthesis, with a diverse array of transformations developed over the past decades for various synthetic applications. Nevertheless, the scope and diversity of biocatalytic alkene difunctionalization have been limited, constraining its synthetic utility. In this study, we repurposed nonheme iron enzymes to generate iron nitrene intermediates for alkene difunctionalization. 4‐hydroxymandelate synthase from Amycolatopsis orientalis ( Ao HMS) was successfully engineered for direct alkene aminoazidation to produce chiral 2‐azidoamines. Directed evolution was performed on Ao HMS to provide evolved variants that could utilize O ‐pivaloylhydroxylamine triflic acid as the nitrene precursor and produced various primary aminoazidation products with up to 44% yield, 44 total turnover number (TTN), and 98.5:1.5 enantiomeric ratio (e.r.). Mechanistic studies indicated that this new biocatalytic transformation proceeds through a stepwise radical addition and azide recombination pathway. This work expands the catalytic toolbox of metalloenzymes and opens up new opportunities for biosynthesis by introducing nonnatural olefin difunctionalization reactions into biocatalysis.

  PublisherDOI

• Engineering Non-haem Enzymes for Nickel-Catalyzed C(sp2)‒S Coupling via Ligand-to-Metal Charge Transfer Photocatalysis

  ChemRxiv · 2025-08-19 · 2 citations

  articleOpen access1st authorCorresponding

  Integrating new metal-catalysed transformations into enzymes is a key objective in biocatalysis. This study introduces photoinduced ligand-to-metal charge transfer (LMCT) as a new strategy for enabling abiotic cross-coupling reactions in metalloenzymes. By tailoring the primary coordination sphere to establish a 2-histidine metal binding site and replacing the iron center with nickel, the ethylene-forming enzyme from Pseudomonas savastanoi (PsEFE) was activated for nickel-catalysed C(sp2)‒S cross-coupling between aryl bromides and thiols. Directed evolution of PsEFE produced highly active variants capable of generating over 50 thioether products in up to 98% yield and 530 total turnover numbers. Mechanistic investigations suggest that this photoenzymatic reaction involves a Ni(II)/Ni(I)/Ni(III) catalytic cycle with generation of a reactive Ni(I) species and thiyl radical via photoinduced LMCT. We anticipate that these findings will inspire further exploration of integrating abiotic cross-coupling transformations into enzymatic catalysis.

  PublisherOA PDFDOI

• Enantioconvergent benzylic C(sp ³ )‒N coupling with a copper-substituted nonheme enzyme

  Science · 2025-08-14 · 18 citations

  articleOpen accessSenior authorCorresponding

  Copper-catalyzed radical C(sp 3 )‒N coupling has become a major focus in synthetic catalysis over the past decade. However, achieving this reaction manifold by using enzymes has remained elusive. In this study, we introduce a photobiocatalytic approach for radical benzylic C(sp 3 )‒N coupling using a copper-substituted nonheme enzyme. Using rhodamine B as a photoredox catalyst, we identified a copper-substituted phenylalanine hydroxylase that facilitates enantioconvergent decarboxylative amination between N -hydroxyphthalimide esters and anilines. Directed evolution remodeled the active site, resulting in high enantioselectivities for most substrates. On the basis of molecular modeling and mechanistic studies, we propose that the enzyme accommodates a copper-anilide complex that reacts with a benzylic radical. This study expands the scope of non-natural biocatalytic transition metal catalysis to copper-catalyzed radical coupling.

  PublisherOA PDFDOI

• Biocatalytic Synthesis of N-Protected α-Amino Acids through 1,3-Nitrogen Migration by Nonheme Iron Enzymes

  Journal of the American Chemical Society · 2025-11-20 · 4 citations

  articleOpen accessCorresponding

  generates an iron-nitrene intermediate capable of aminating benzylic and allylic α-C-H bonds of carboxylic acids. Directed evolution has been performed to optimize the IPNS variant to accommodate a broad range of azanyl esters, yielding α-amino acids (24 examples) with up to 92% yield, 1477 total turnover number (TTN), and 99% enantiomeric excess (ee).

  PublisherOA PDFDOI

• Directed Evolution of Copper-Substituted Nonheme Enzymes for Enantioselective Alkene Oxytrifluoromethylation

  Journal of the American Chemical Society · 2025-08-05 · 11 citations

  articleOpen accessSenior authorCorresponding

  Trifluoromethylation is a coveted transformation due to the unique properties of the trifluoromethyl (−CF3) group and the importance of organofluorine compounds. Enzymes that can catalyze the formation of C−CF3 bonds would therefore be highly desirable. However, such “trifluoromethylases” are rare. Here, we report a biocatalytic platform for constructing CF3-substituted lactones via intramolecular alkene oxytrifluoromethylation based on hydroxymandelate synthase from Amycolatopsis orientalis (AoHMS), a nonheme iron enzyme. The key feature that enabled the development of this enzymatic system was the substitution of the native catalytic iron center with copper. This modification retained the ability of the AoHMS protein scaffold to facilitate CF3 radical generation while harnessing the exceptional catalytic activity of copper for alkene oxyfunctionalizations. Directed evolution of copper-substituted AoHMS resulted in an engineered variant capable of producing β-, γ-, and δ-lactones bearing quaternary stereocenters with high efficiency and enantiocontrol (up to 99% yield and 98.5:1.5 e.r.). This work not only expands the biocatalytic toolbox for organofluorine synthesis but also highlights the immense potential of metal-substituted nonheme iron enzymes for evolving new-to-nature transformations.

  PublisherOA PDFDOI

• Unlocking Lewis acid catalysis in non-haem enzymes for an abiotic ene reaction

  Nature Catalysis · 2025-07-04 · 16 citations

  articleSenior author
  PublisherDOI

• Biocatalytic Olefin Difunctionalization for Synthesis of Chiral 2‐Azidoamines Using Nonheme Iron Enzymes

  Angewandte Chemie International Edition · 2025-08-10 · 7 citations

  articleOpen accessSenior authorCorresponding

  Alkene difunctionalization represents an important category of reactions in organic synthesis, with a diverse array of transformations developed over the past decades for various synthetic applications. Nevertheless, the scope and diversity of biocatalytic alkene difunctionalization have been limited, constraining its synthetic utility. In this study, we repurposed nonheme iron enzymes to generate iron nitrene intermediates for alkene difunctionalization. 4-hydroxymandelate synthase from Amycolatopsis orientalis (AoHMS) was successfully engineered for direct alkene aminoazidation to produce chiral 2-azidoamines. Directed evolution was performed on AoHMS to provide evolved variants that could utilize O-pivaloylhydroxylamine triflic acid as the nitrene precursor and produced various primary aminoazidation products with up to 44% yield, 44 total turnover number (TTN), and 98.5:1.5 enantiomeric ratio (e.r.). Mechanistic studies indicated that this new biocatalytic transformation proceeds through a stepwise radical addition and azide recombination pathway. This work expands the catalytic toolbox of metalloenzymes and opens up new opportunities for biosynthesis by introducing nonnatural olefin difunctionalization reactions into biocatalysis.

  PublisherOA PDFDOI

• Radical-relay C(sp3)–H azidation catalyzed by an engineered nonheme iron enzyme

  Methods in enzymology on CD-ROM/Methods in enzymology · 2024-01-01

  articleOpen accessSenior authorCorresponding
  PublisherOA PDFDOI

Recent grants

• Expanding the chemistry of life: New enzymatic platforms for synthesis of bioactive organofluorines

  NIH · $747k · 2018–2022

• Expanding the chemistry of life: New enzymatic platforms for synthesis of bioactive organofluorines

  NIH · $95k · 2018–2020

• A Biocatalytic System for Enantioselective Carbon-Boron Bond Formation

  NIH · $49k · 2017–2018

Frequent coauthors

• Frances H. Arnold

  33 shared

• Marc Garcia‐Borràs

  University of Girona

  25 shared

• John T. Groves

  23 shared

• Gonzalo Jiménez‐Osés

  Ikerbasque

  22 shared

• K. N. Houk

  University of California, Los Angeles

  18 shared

• Anuvab Das

  17 shared

• Lucas Schaus

  California Institute of Technology

  17 shared

• Anders M. Knight

  Codexis (United States)

  17 shared

Labs

• HUANG LABPI

Education

• NIH Pathway to Independence Postdoctoral Fellow, Chemistry and Chemical Engineering

  California Institute of Technology

  2019

• Ph.D., Chemistry

  Princeton University

  2016

• B.S., Chemistry

  University of Science and Technology of China

  2010

Awards & honors

• HHMI International Predoctoral Fellow
• NIH NRSA Postdoctoral Fellow
• NIH Pathway to Independence Postdoctoral Fellow