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1. Metal‐Templated, Tight Loop Conformation of a Cys‐X‐Cys Biomimetic Assembles a Dimanganese Complex

   https://doi.org/10.1002/anie.201913259  

   Le, Trung; Nguyen, Hao; Perez, Lisa M.; Darensbourg, Donald J.; Darensbourg, Marcetta Y. (January 2020, Angewandte Chemie International Edition)

   Abstract With the goal of generating anionic analogues to MN₂S₂⋅Mn(CO)₃Br we introduced metallodithiolate ligands, MN₂S₂²⁻prepared from the Cys‐X‐Cys biomimetic, ema⁴⁻ligand (ema=N,N′‐ethylenebis(mercaptoacetamide); M=Ni^II, [V^IV≡O]²⁺and Fe^III) to Mn(CO)₅Br. An unexpected, remarkably stable dimanganese product, (H₂N₂(CH₂C=O(μ‐S))₂)[Mn(CO)₃]₂resulted from loss of M originally residing in the N₂S₂⁴⁻pocket, replaced by protonation at the amido nitrogens, generating H₂ema²⁻. Accordingly, the ema ligand has switched its coordination mode from an N₂S₂⁴⁻cavity holding a single metal, to a binucleating H₂ema²⁻with bridging sulfurs and carboxamide oxygens within Mn‐μ‐S‐CH₂‐C‐O, 5‐membered rings. In situ metal‐templating by zinc ions gives quantitative yields of the Mn₂product. By computational studies we compared the conformations of “linear” ema⁴⁻to ema⁴⁻frozen in the “tight‐loop” around single metals, and to the “looser” fold possible for H₂ema²⁻that is the optimal arrangement for binucleation. XRD molecular structures show extensive H‐bonding at the amido‐nitrogen protons in the solid state. 

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2. Protein oxidation involved in Cys-Tyr post-translational modification

   https://doi.org/10.1016/j.jinorgbio.2017.08.028  

   Hromada, Susan E.; Hilbrands, Adam M.; Wolf, Elysa M.; Ross, Jackson L.; Hegg, Taylor R.; Roth, Andrew G.; Hollowell, Matthew T.; Anderson, Carolyn E.; Benson, David E. (November 2017, Journal of Inorganic Biochemistry)
3. Characterizing Transient Protein–Protein Interactions by Trp-Cys Quenching and Computer Simulations

   https://doi.org/10.1021/acs.jpclett.2c02723  

   Heo, Lim; Gamage, Kasun; Valdes-Garcia, Gilberto; Lapidus, Lisa J.; Feig, Michael (November 2022, The Journal of Physical Chemistry Letters)
4. Chromophore Optimization in Organometallic Au(III) Cys Arylation of Peptides and Proteins for 266 nm Photoactivation

   https://doi.org/10.1021/acs.analchem.4c03001  

   Silzel, Jacob_W; Chen, Chengwei; Sanchez-Marsetti, Colomba; Farias, Phillip; Carta, Veronica; Harman, W_Hill; Julian, Ryan_R (August 2024, Analytical Chemistry)
5. A De Novo‐Designed Artificial Metallopeptide Hydrogenase: Insights into Photochemical Processes and the Role of Protonated Cys

   https://doi.org/10.1002/cssc.202100122  

   Malayam_Parambath, Sreya; Williams, Ashley_E; Hunt, Leigh_Anna; Selvan, Dhanashree; Hammer, Nathan_I; Chakraborty, Saumen (April 2021, ChemSusChem)

   Abstract Hydrogenase enzymes produce H₂gas, which can be a potential source of alternative energy. Inspired by the [NiFe] hydrogenases, we report the construction of a de novo‐designed artificial hydrogenase (ArH). The ArH is a dimeric coiled coil where two cysteine (Cys) residues are introduced at tandema/dpositions of a heptad to create a tetrathiolato Ni binding site. Spectroscopic studies show that Ni binding significantly stabilizes the peptide producing electronic transitions characteristic of Ni‐thiolate proteins. The ArH produces H₂photocatalytically, demonstrating a bell‐shaped pH‐dependence on activity. Fluorescence lifetimes and transient absorption spectroscopic studies are undertaken to elucidate the nature of pH‐dependence, and to monitor the reaction kinetics of the photochemical processes. pH titrations are employed to determine the role of protonated Cys on reactivity. Through combining these results, a fine balance is found between solution acidity and the electron transfer steps. This balance is critical to maximize the production of Ni^I‐peptide and protonation of the Ni^II−H⁻intermediate (Ni−R) by a Cys (pK_a≈6.4) to produce H₂. 

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