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1. Zn-Enhanced Asp-Rich Antimicrobial Peptides: N-Terminal Coordination by Zn(II) and Cu(II), Which Distinguishes Cu(II) Binding to Different Peptides

   https://doi.org/10.3390/ijms22136971  

   Miller, Adriana; Matera-Witkiewicz, Agnieszka; Mikołajczyk, Aleksandra; Wątły, Joanna; Wilcox, Dean; Witkowska, Danuta; Rowińska-Żyrek, Magdalena (July 2021, International Journal of Molecular Sciences)

   null (Ed.)

   The antimicrobial activity of surfactant-associated anionic peptides (SAAPs), which are isolated from the ovine pulmonary surfactant and are selective against the ovine pathogen Mannheimia haemolytica, is strongly enhanced in the presence of Zn(II) ions. Both calorimetry and ITC measurements show that the unique Asp-only peptide SAAP3 (DDDDDDD) and its analogs SAAP2 (GDDDDDD) and SAAP6 (GADDDDD) have a similar micromolar affinity for Zn(II), which binds to the N-terminal amine and Asp carboxylates in a net entropically-driven process. All three peptides also bind Cu(II) with a net entropically-driven process but with higher affinity than they bind Zn(II) and coordination that involves the N-terminal amine and deprotonated amides as the pH increases. The parent SAAP3 binds Cu(II) with the highest affinity; however, as shown with potentiometry and absorption, CD and EPR spectroscopy, Asp residues in the first and/or second positions distinguish Cu(II) binding to SAAP3 and SAAP2 from their binding to SAAP6, decreasing the Cu(II) Lewis acidity and suppressing its square planar amide coordination by two pH units. We also show that these metal ions do not stabilize a membrane disrupting ability nor do they induce the antimicrobial activity of these peptides against a panel of human pathogens. 

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2. Encapsulation of tricopper cluster in a synthetic cryptand enables facile redox processes from Cu ^I Cu ^I Cu ^I to Cu ^II Cu ^II Cu ^II states

   https://doi.org/10.1039/D0SC05441K  

   Zhang, Weiyao; Moore, Curtis E.; Zhang, Shiyu (March 2021, Chemical Science)

   null (Ed.)

   One-pot reaction of tris(2-aminoethyl)amine (TREN), [Cu I (MeCN) 4 ]PF 6 , and paraformaldehyde affords a mixed-valent [ TREN4 Cu II Cu I Cu I (μ 3 -OH)](PF 6 ) 3 complex. The macrocyclic azacryptand TREN4 contains four TREN motifs, three of which provide a bowl-shape binding pocket for the [Cu 3 (μ 3 -OH)] 3+ core. The fourth TREN caps on top of the tricopper cluster to form a cryptand, imposing conformational constraints and preventing solvent interaction. Contrasting the limited redox capability of synthetic tricopper complexes reported so far, [ TREN4 Cu II Cu I Cu I (μ 3 -OH)](PF 6 ) 3 exhibits several reversible single-electron redox events. The distinct electrochemical behaviors of [ TREN4 Cu II Cu I Cu I (μ 3 -OH)](PF 6 ) 3 and its solvent-exposed analog [ TREN3 Cu II Cu II Cu II (μ 3 -O)](PF 6 ) 4 suggest that isolation of tricopper core in a cryptand enables facile electron transfer, allowing potential application of synthetic tricopper complexes as redox catalysts. Indeed, the fully reduced [ TREN4 Cu I Cu I Cu I (μ 3 -OH)](PF 6 ) 2 can reduce O 2 under acidic conditions. The geometric constraints provided by the cryptand are reminiscent of Nature's multicopper oxidases (MCOs). For the first time, a synthetic tricopper cluster was isolated and fully characterized at Cu I Cu I Cu I ( 4a ), Cu II Cu I Cu I ( 4b ), and Cu II Cu II Cu I ( 4c ) states, providing structural and spectroscopic models for many intermediates in MCOs. Fast electron transfer rates (10 5 to 10 6 M −1 s −1 ) were observed for both Cu I Cu I Cu I /Cu II Cu I Cu I and Cu II Cu I Cu I /Cu II Cu II Cu I redox couples, approaching the rapid electron transfer rates of copper sites in MCO. 

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3. Stability constant determination of sulfur and selenium amino acids with Cu(II) and Fe(II)

   https://doi.org/10.1016/j.jinorgbio.2019.03.001  

   Murphy, Jaime M.; Gaertner, Andrea A.E.; Williams, Tyler; McMillen, Colin D.; Powell, Brian A.; Brumaghim, Julia L. (June 2019, Journal of Inorganic Biochemistry)
4. Explaining How α-Hydroxamate Ligands Control the Formation of Cu(II)-, Ni(II)-, and Zn(II)-Containing Metallacrowns

   https://doi.org/10.1021/acs.inorgchem.9b02724  

   Ostrowska, Malgorzata; Toporivska, Yuliya; Golenya, Irina A.; Shova, Sergiu; Fritsky, Igor O.; Pecoraro, Vincent L.; Gumienna-Kontecka, Elzbieta (November 2019, Inorganic Chemistry)
5. Chemoselective and Diastereoconvergent Cu(II)-Catalyzed Aerobic Endoperoxidation of Polycarbonyls

   https://doi.org/10.1021/acs.orglett.7b01225  

   Giarrusso, James; Do, Dung T.; Johnson, Jeffrey S. (June 2017, Organic Letters)