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Nkyaagye E, Limbach MN, Do TD. Molecular Selectivity in the Binding of Alkali Metals, Alkaline Earth Metals, First-Row Transition Metals, and Lanthanides with Cyclic Depsipeptides. J Phys Chem B 2024; 128:1209-1219. [PMID: 38293785 DOI: 10.1021/acs.jpcb.3c08385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Beauvericin (BEA) and enniatins (ENN) are cyclic hexadepsipeptide mycotoxins known for their ionophoric activities across cell membranes. While their ability to selectively bind alkali ions to form binary complexes has been studied, their interaction with multivalent metal ions to form higher-order complexes remains less explored. We report the unique characteristics of the 1:2, Mn+:BEA or ENN complexes with monovalent, divalent, and trivalent metal ions. A thorough IMS-MS analysis underscores the substantial interplay among ionic radii, coordination numbers, and their impact on conformational selection within higher-order complexes that is pertinent to ion transport. Transition metals offer insights into the effects of ion radii and ligand side chains on conformational selection, while lanthanide complexes enable a direct evaluation of coordination chemistry. An intriguing finding concerning the lanthanide complexes involves an unexpected C-H bond activation, wherein water ligands may catalyze the deprotonation of the cyclic peptides.
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Affiliation(s)
- Emmanuel Nkyaagye
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Miranda N Limbach
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Thanh D Do
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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Xie L, He A, Li D, Li T, Yang L, Huang K, Xu Y, Zhao G, Liu J, Liu K, Chen J, Ozaki Y, Noda I. Deprotonation from an OH on myo-Inositol Promoted by μ 2-Bridges with Possible Regioselectivity/Chiral Selectivity. Inorg Chem 2022; 61:6138-6148. [PMID: 35412316 DOI: 10.1021/acs.inorgchem.2c00288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Single-crystal structures of myo-inositol complexes with erbium ([Er2(C6H11O6)2(H2O)5Cl2]Cl2(H2O)4, denoted ErI hereafter) and strontium (Sr(C6H12O6)2(H2O)2Cl2, denoted SrI hereafter) are described. In ErI, deprotonation occurs on an OH of myo-inositol, although the complex is synthesized in an acidic solution, and the pKa values of all of the OHs in myo-inositol are larger than 12. The deprotonated OH is involved in a μ2-bridge. The polarization from two Er3+ ions activates the chemically relatively inert OH and promotes deprotonation. In the stable conformation of myo-inositol, there are five equatorial OHs and one axial OH. The deprotonation occurs on the only axial OH, suggesting that the deprotonation possesses characteristics of regioselectivity/chiral selectivity. Two Er3+ ions in the μ2-bridge are stabilized by five-membered rings formed by chelating Er3+ with an O-C-C-O moiety. As revealed by the X-ray crystallography study, the absolute values of the O-C-C-O torsion angles decrease from ∼60 to ∼45° upon chelating. Since the O-C-C-O moiety is within a six-membered ring, the variation of the torsion angle may exert distortion of the chair conformation. Quantum chemistry calculation results indicate that an axial OH flanked by two equatorial OHs (double ax-eq motif) is favorable for the formation of a μ2-bridge, accounting for the selectivity. The double ax-eq motif may be used in a rational design of high-performance catalysts where deprotonation with high regioselectivity/chiral selectivity is carried out.
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Affiliation(s)
- Linchen Xie
- State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, China.,Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,School of Biology and Medicine, Beijing City University, Beijing 100094, China
| | - Anqi He
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Da Li
- School of Biology and Medicine, Beijing City University, Beijing 100094, China
| | - Tianyi Li
- State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, China
| | - Limin Yang
- State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, China
| | - Kun Huang
- School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yizhuang Xu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Guozhong Zhao
- Department of Physics, Capital Normal University, Beijing Advanced Innovation Center of Imaging Technology, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Beijing 100048, China
| | - Jingyu Liu
- Department of Physics, Capital Normal University, Beijing Advanced Innovation Center of Imaging Technology, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Beijing 100048, China
| | - Kexin Liu
- State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, China
| | - Jia'er Chen
- State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, China
| | - Yukihiro Ozaki
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,School of Biological and Environmental Sciences, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan
| | - Isao Noda
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.,Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, United States
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