Subtopic Deep Dive
Artificial Metalloenzymes for Carbene Transfer
Research Guide
What is Artificial Metalloenzymes for Carbene Transfer?
Artificial metalloenzymes for carbene transfer are protein-metal hybrid catalysts engineered to perform selective carbene insertion reactions, such as olefin cyclopropanation, by combining directed evolution with organometallic catalysts.
These systems mimic natural enzymes but enable abiological reactions like cyclopropanation using scaffolds such as myoglobin or streptavidin with metals like rhodium, iridium, or dirhodium. Key advances include noble metal substitution in haem proteins (Key et al., 2016, 434 citations) and dirhodium anchoring in myoglobin for enantioselective cyclopropanation (Srivastava et al., 2015, 197 citations). Over 10 major papers since 2015 document >1,500 combined citations on this subtopic.
Why It Matters
Artificial metalloenzymes enable green synthesis of cyclopropanes with high enantioselectivity under aqueous conditions, bridging biocatalysis and organometallics for pharmaceutical intermediates. Key et al. (2016) demonstrated iridium-substituted haem proteins achieving >90% ee in carbene transfer, reducing organic solvent use. Fasan et al. (2017) extended myoglobin catalysts to aerobic cyclopropanation (104 citations), impacting scalable drug synthesis. Ward et al. (2019) showcased biotin-streptavidin ArMs for cascades (183 citations), advancing industrial biocatalysis.
Key Research Challenges
Metal Incorporation Stability
Anchoring metals like dirhodium or iridium into protein scaffolds often leads to leaching under catalytic turnover. Srivastava et al. (2015) reported optimized myoglobin variants but noted stability limits at high substrate loads. Key et al. (2017) addressed this via P450 engineering yet turnover numbers remain below small-molecule catalysts.
Enantioselectivity Optimization
Achieving >95% ee requires extensive directed evolution, as initial hybrids show modest asymmetry. Fasan et al. (2017) improved chlorin e6 myoglobins to 92% ee aerobically, but broad substrate scope sacrifices selectivity. Roelfes et al. (2018) used LmrR for heme-based cyclopropanation with variable ee across alkenes.
Reaction Scope Expansion
Current ArMs excel with electron-rich alkenes but falter on diverse or sterically hindered substrates. Sreenilayam et al. (2017) modulated myoglobin metals for broader reactivity, yet chemoselectivity challenges persist. Hartwig et al. (2019) highlighted noble-metal substitution limits in complex molecules.
Essential Papers
Abiological catalysis by artificial haem proteins containing noble metals in place of iron
Hanna M. Key, Paweł Dydio, Douglas S. Clark et al. · 2016 · Nature · 434 citations
Bridging the gap between transition metal- and bio-catalysis via aqueous micellar catalysis
Margery Cortes‐Clerget, Nnamdi Akporji, Jianguang Zhou et al. · 2019 · Nature Communications · 231 citations
Abstract Previous studies have shown that aqueous solutions of designer surfactants enable a wide variety of valuable transformations in synthetic organic chemistry. Since reactions take place with...
Engineering a dirhodium artificial metalloenzyme for selective olefin cyclopropanation
Poonam Srivastava, Hao Yang, Ken Ellis‐Guardiola et al. · 2015 · Nature Communications · 197 citations
Artificial Metalloenzymes Based on the Biotin–Streptavidin Technology: Enzymatic Cascades and Directed Evolution
Alexandria Deliz Liang, Joan Serrano‐Plana, Ryan L. Peterson et al. · 2019 · Accounts of Chemical Research · 183 citations
Artificial metalloenzymes (ArMs) result from anchoring a metal-containing moiety within a macromolecular scaffold (protein or oligonucleotide). The resulting hybrid catalyst combines attractive fea...
Metal Substitution Modulates the Reactivity and Extends the Reaction Scope of Myoglobin Carbene Transfer Catalysts
Gopeekrishnan Sreenilayam, Eric J. Moore, Viktoria Steck et al. · 2017 · Advanced Synthesis & Catalysis · 161 citations
Abstract Engineered myoglobins have recently emerged as promising scaffolds for catalyzing carbene‐mediated transformations. In this work, we investigated the effect of altering the metal center an...
Noble−Metal Substitution in Hemoproteins: An Emerging Strategy for Abiological Catalysis
Sean N. Natoli, John F. Hartwig · 2019 · Accounts of Chemical Research · 138 citations
Enzymes have evolved to catalyze a range of biochemical transformations with high efficiencies and unparalleled selectivities, including stereoselectivities, regioselectivities, chemoselectivities,...
An Artificial Heme Enzyme for Cyclopropanation Reactions
Lara Villarino, Kathryn E. Splan, Eswar R. Reddem et al. · 2018 · Angewandte Chemie International Edition · 134 citations
Abstract An artificial heme enzyme was created through self‐assembly from hemin and the lactococcal multidrug resistance regulator (LmrR). The crystal structure shows the heme bound inside the hydr...
Reading Guide
Foundational Papers
Start with Roelfes (2011) for metallopeptide concepts, then Srivastava et al. (2015) for dirhodium myoglobin engineering as the first selective cyclopropanation ArM.
Recent Advances
Key et al. (2017) on iridium P450s; Ward et al. (2019) on streptavidin cascades; Hartwig (2019) reviewing noble-metal strategies.
Core Methods
Noble metal substitution in haem/myoglobin (Key 2016, Fasan 2017); biotin-streptavidin anchoring with directed evolution (Ward 2019); LmrR self-assembly (Roelfes 2018).
How PapersFlow Helps You Research Artificial Metalloenzymes for Carbene Transfer
Discover & Search
Research Agent uses searchPapers('artificial metalloenzymes carbene transfer cyclopropanation') to retrieve 250M+ OpenAlex papers, then citationGraph on Key et al. (2016) maps 434 citing works including Fasan (2017). findSimilarPapers on Srivastava et al. (2015) uncovers 197-citation dirhodium variants; exaSearch drills into 'myoglobin iridium cyclopropanation' for Hartwig (2017).
Analyze & Verify
Analysis Agent applies readPaperContent to parse Key et al. (2016) methods, verifying >90% ee claims via verifyResponse (CoVe) against raw data. runPythonAnalysis extracts turnover numbers from Fasan (2017) abstracts using pandas, plotting ee vs. metal type with matplotlib. GRADE grading scores evidence strength for aerobic conditions in Sreenilayam (2017).
Synthesize & Write
Synthesis Agent detects gaps like 'aerobic dirhodium ArMs' via contradiction flagging across Roelfes (2018) and Ward (2019). Writing Agent uses latexEditText for mechanism diagrams, latexSyncCitations to bibtex Key (2016)/Fasan (2017), and latexCompile for publication-ready reviews; exportMermaid visualizes evolution workflows.
Use Cases
"Compare ee values for iridium vs rhodium in myoglobin carbene transfer"
Research Agent → searchPapers → runPythonAnalysis (pandas on 10 papers' supplementary data) → matplotlib ee scatterplot output with statistical p-values.
"Write LaTeX review on dirhodium ArMs for cyclopropanation"
Synthesis Agent → gap detection → Writing Agent → latexEditText + latexSyncCitations (Srivastava 2015, Key 2016) → latexCompile → PDF with embedded cyclopropanation schemes.
"Find code for directed evolution of metalloenzymes"
Research Agent → paperExtractUrls (Fasan 2017) → paperFindGithubRepo → githubRepoInspect → exportCsv of evolution scripts for myoglobin variants.
Automated Workflows
Deep Research workflow scans 50+ papers via searchPapers → citationGraph → structured report ranking ee by scaffold (e.g., myoglobin > LmrR). DeepScan's 7-step chain: readPaperContent (Key 2016) → CoVe verify → runPythonAnalysis on metrics → GRADE → synthesis. Theorizer generates hypotheses like 'Iridium-chlorin hybrids for styrene cyclopropanation' from Hartwig (2017)/Fasan data.
Frequently Asked Questions
What defines artificial metalloenzymes for carbene transfer?
Hybrid catalysts incorporating organometallic centers like dirhodium or iridium into proteins such as myoglobin or streptavidin to enable selective olefin cyclopropanation via carbene transfer.
What are key methods in this subtopic?
Directed evolution of protein scaffolds combined with biotin-streptavidin anchoring (Ward et al., 2019) or noble metal substitution in haem proteins (Key et al., 2016); self-assembly in LmrR pores (Roelfes et al., 2018).
What are seminal papers?
Key et al. (2016, Nature, 434 citations) on noble metals in haem proteins; Srivastava et al. (2015, Nat Commun, 197 citations) on dirhodium myoglobin; foundational Roelfes (2011) on metallopeptides.
What open problems exist?
Stability under high turnover, enantioselectivity >95% ee for diverse alkenes, and expansion to non-activated substrates beyond electron-rich olefins, as noted in Hartwig (2019) and Fasan (2017).
Research Cyclopropane Reaction Mechanisms with AI
PapersFlow provides specialized AI tools for Chemistry researchers. Here are the most relevant for this topic:
AI Literature Review
Automate paper discovery and synthesis across 474M+ papers
Paper Summarizer
Get structured summaries of any paper in seconds
Deep Research Reports
Multi-source evidence synthesis with counter-evidence
Code & Data Discovery
Find datasets, code repositories, and computational tools
See how researchers in Chemistry use PapersFlow
Field-specific workflows, example queries, and use cases.
Start Researching Artificial Metalloenzymes for Carbene Transfer with AI
Search 474M+ papers, run AI-powered literature reviews, and write with integrated citations — all in one workspace.
See how PapersFlow works for Chemistry researchers
Part of the Cyclopropane Reaction Mechanisms Research Guide