H.S. Shafaat

@shafaatlab.bsky.social

Bioinorganic Chemistry, Lasers, and Proteins! Primarily student run account

Celebrating the wonderful visit from Madeline Ho from the Hoffman and Chen labs at Northwestern to discuss their beautiful ENDOR EPR spectroscopy studies on non-symmetrical [Fe-S] clusters. We enjoyed your talk, chatting with the group, and sharing our science.

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From lab days to beach nights and gift-exchange chaos (featuring one cat supervisor 🐈), the Shafaat Group & friends are wishing you warmth, joy, and a happy holiday season! ✨🎄💫

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Check out our POTW! Thanks, Henry, for highlighting this study showing that ENDOR S/N can be significantly improved through frequency multiplexing—simultaneously pulsing multiple nuclear frequencies and decoding them via Hadamard transformation. tinyurl.com/ur73256y

Sensitivity Enhancement in Pulsed Hyperfine EPR Spectroscopy with Hadamard-Encoded Acquisition

Electron–nuclear double resonance (ENDOR) is a powerful tool for determining the spatial and electronic structure of paramagnetic systems. It often suffers from a limited signal-to-noise ratio (SNR), ...

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We are thrilled to welcome Prof. Kate Buettner to our group for her sabbatical! She'll be helping us explore exciting new frontiers in metalloproteins– we can’t wait to see where this journey takes us!

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Curious how enzymes adapt to oxygen? Our new collaborative review with the @Rhys_G and @Greeninglab groups explores how oxygen-tolerant [NiFe]-hydrogenases evolved across microbes to thrive in aerobic environments, revealing innovative metabolic changes in Earth’s evolving redox landscape.

Diverse lineages and adaptations of oxygen-adapted hydrogenases

Hydrogenases allow microorganisms to consume and produce hydrogen gas (H2). Although most hydrogenases are oxygen (O2)-sensitive, recent studies show …

sciencedirect.com

Check out our POTW! Thanks, James, for highlighting this study using ultrahigh-throughput FACS to screen 10⁹ variants/day! Engineered enzymes showed up to 16× improved activity on highly stable N-aryl amide & carbamate bonds. bit.ly/4mAn4nB

Ultrahigh-Throughput Activity Engineering of Promiscuous Amidases through a Fluorescence-Activated Cell Sorting Assay

Ultrahigh-throughput methods such as flow cytometry are ideal tools for the directed evolution of enzymes by enabling the screening of up to 109 variants per day. In this study, we developed an assay based on fluorescence-activated cell sorting (FACS) for the detection and engineering of amidase activity in whole cells. The assay establishes a stable genotype–phenotype linkage by coupling coumarin-based hydrolysis products to intracellular glutathione via a recombinantly coexpressed glutathione S-transferase. To demonstrate the applicability of the FACS-based assay, we engineered an amidase from Sphingomonas alpina (SaAmd) by screening combinatorial libraries with multiple amino acid positions randomized simultaneously. SaAmd variants containing proximal double mutations exhibited not only almost 5-fold improved activity against structurally different amide substrates but also coevolved promiscuous carbamate- and ester-hydrolyzing activities, which exceeded the wildtype activity up to 6-fold. Importantly, triple variants featuring distal mutations in three highly flexible loop regions, displayed up to 16-fold enhanced specific activities toward small molecules containing highly stable N-aryl amide and carbamate bonds. These motifs are commonly used as protecting groups for amines in organic synthesis but can also be found in environmental contaminants like pesticides and plastic waste. Therefore, the developed FACS-assisted assay has great potential to accelerate the engineering of amidases for versatile biotechnological applications.

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Check out our POTW! Thanks, Henry, for highlighting this study, which shows that aerolysin nanopore sensing can distinguish cis/trans isomers of proline-containing peptides at the single-molecule level, opening doors for structural analysis and PPIase inhibitor screening. rsc.li/3SGyS9Y

Single-molecule nanopore sensing of proline cis/trans amide isomers

Molecules known as stereoisomers possess identical numbers and types of atoms, which are oriented differently in space. Cis–trans isomerization of proline, a distinctive case of stereoisomerism in pep...

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Congrats, Josephine and the team!! Check out our newest mechanistic deep dive into R2lox: Isotope labeling and EPR spectroscopy reveal that this Mn/Fe enzyme activates C–H bonds to form a unique Tyr–Val crosslink via a Mn⁴⁺/Fe⁴⁺ intermediate.

Selective isotope labeling probes the chemical capacity and reaction mechanism of a heterobimetallic Mn/Fe protein

The R2-like ligand binding oxidase (R2lox) forms a novel tyrosine-valine crosslink upon O2 activation, reflecting an overall two-electron oxidation re…

sciencedirect.com

Check out our POTW! Thanks, Aadhishre, for highlighting the study from the Schäfer and Happe groups identifying ToHydA, a Group B [FeFe]-hydrogenase with remarkable O₂ stability, which shows that the conserved cysteines and a hydrophobic loop support the protective Hinact state.

Big shoutout to the team who rocked the Willow Community School Science Fair this weekend! We had so much fun making ‘oobleck’ to show off non-Newtonian fluids and letting kids get creative with pH indicator art. Nothing better than sparking curiosity!

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