Previous work shows that Im9 folds in a two-state transition while its homologue Im7 folds in a three-state transition via an on-pathway kinetic intermediate state (KIS), with this difference being related to frustration in the structure of Im7. We have used NMR spectroscopy to study conformational dynamics connected to the frustration. A combination of equilibrium peptide N(1)H/N(2)H exchange, model-free analyses of backbone NH relaxation data and relaxation dispersion (RD)-NMR shows that the native state of Im7 is in equilibrium with an intermediate state that is lowly populated [equilibrium intermediate state (EIS)]. Comparison of kinetic and thermodynamic parameters describing the EIS native-state equilibrium obtained by RD-NMR with previously reported parameters describing the KIS native-state equilibrium obtained from stopped-flow fluorescence studies of refolding His-tagged Im7 shows that the KIS and the EIS are the same species. (15)N chemical shifts of the EIS obtained from the RD-NMR analysis show that residues forming helix III in the native state are unstructured in the EIS while other residues experiencing frustration in the native state are in structured regions of the EIS. We show that binding of Im7 and its L53A/I54A variant (which resembles the EIS as shown in previous work) to the cognate partner for Im7, the DNase domain of colicin E7, causes the dynamic processes associated with the frustration to be dampened.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.jmb.2011.09.038 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Purpose: Radiotherapy (RT)/cetuximab (C) demonstrated superiority over RT alone for locally advanced squamous head and neck cancer. We tested this in completely resected, intermediate-risk cancer.
Methods: Patients had squamous cell carcinoma of the head and neck (SCCHN) of the oral cavity, oropharynx, or larynx, with one or more risk factors warranting postoperative RT.
Atomically Dispersed Ta-O-Co Sites Capable of Mitigating Side Reaction Occurrence for Stable Lithium-Oxygen Batteries.
J Am Chem Soc
January 2025
Engineering Research Center of Advanced Rare Earth Materials, Department of Chemistry, Tsinghua University, Beijing 100084, China.
The side reactions accompanying the charging and discharging process, as well as the difficulty in decomposing the discharge product lithium peroxide, have been important issues in the research field of lithium-oxygen batteries for a long time. Here, single atom Ta supported by CoO hollow sphere was designed and synthesized as a cathode catalyst. The single atom Ta forms an electron transport channel through the Ta-O-Co structure to stabilize octahedral Co sites, forming strong adsorption with reaction intermediates and ultimately forming a film-like lithium peroxide that is highly dispersed.
View Article and Find Full Text PDFAdvances in accessing rare oxidation states of nickel for catalytic innovation.
Chem Commun (Camb)
January 2025
Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
Nickel catalysis has experienced a renaissance over the past two decades, driven by its ability to access diverse oxidation states (0 to +4) and unique reactivity. This review consolidates the advancements in nickel chemistry, providing an overview of ligands that stabilize specific nickel oxidation states. The stability, reactivity, and catalytic applications of Ni sources, including generation from air- and moisture-stable Ni precursors, are discussed, along with the roles of Ni and Ni intermediates in catalytic cycles.
View Article and Find Full Text PDFDynamics of Pyrene Excimer in a Cholesteryl-based Supramolecular Host Matrix.
Chemphyschem
January 2025
IISER Bhopal: Indian Institute of Science Education and Research Bhopal, Department of Chemistry, Bhopal Bypass Road, Bhauri, 462066, Bhopal, INDIA.
Aggregation-caused quenching (ACQ) reduces luminescence and compromises brightness in solid-state displays, necessitating strategies to mitigate its effects for enhanced performance. This study presents cost-effective method to mitigate ACQ of pyrene by co-assembling polycyclic aromatic hydrocarbons within low molecular weight gelator. Synthesized from readily available materials-cholesteryl chloroformate and pentaerythritol-in one-step reaction, gelator incorporates four cholesteryl units, reported to promote robust supramolecular gels in various solvents.
View Article and Find Full Text PDFReactions of Surface Peroxides Contribute to Rates and Selectivities for CH Epoxidation on Silver.
ACS Catal
January 2025
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
Partial oxidation of ethylene over silver catalysts produces more than 30 million metric tons of ethylene oxide (EO) annually. However, the form of active silver surfaces, reactive oxygen species, and dominant pathways of this chemical reaction remains controversial despite decades of research. Here, we use Raman spectroscopy and transient kinetic measurements to demonstrate that higher coverages of peroxide species, present only upon Ag oxide surfaces that form , correlate with greater selectivities to EO.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!