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The present study focuses on designing mutant peptides derived from the lanthanide binding tag (LBT) to enhance selectivity for trivalent actinide (An3+) ions over lanthanide (Ln3+) metal ions (M). The LBT is a short peptide consisting of only 17 amino acids, and is known for its high affinity towards Ln3+. LBT was modified by substituting hard-donor ligands like asparagine (ASN or N) and aspartic acid (ASP or D) with softer ligand cysteine (CYS or C) to create four mutant peptides: M-LBT (wild-type), M-N103C, M-D105C, and M-N103C–D105C. All atom molecular dynamics (MD) simulations were employed to analyze the binding dynamics and affinities of these mutants with Eu3+ and Am3+ as representatives for trivalent Ln and An ions, respectively. Hydrogen bond dynamics and short-range Coulomb interactions are evaluated from the equilibrium run for all the systems. The study utilized an enhanced sampling method, namely, well-tempered meta-dynamics (WT-MtD), to overcome sampling challenges and obtain converged free energy profiles for the metal-binding interactions. Our simulations studies indicate that both single and double mutations alter the coordination environment within the peptide's binding pocket, potentially increasing Am3+ selectivity over the Eu3+ ion. The binding of Eu3+ and Am3+ to LBT systems was analyzed, showing an unbinding energy barrier of ∼60 kJ mol−1 for the wild-type. The N103C variant increases the binding strength with a barrier over 100 kJ mol−1, while D105C shows a preference for Am3+ with a barrier around 70 kJ mol−1. The doubly mutated N103C–D105C variant favors Am3+ by more than 20 kJ mol−1. The findings suggest N103C for general chelation and N103C–D105C for preferential trivalent Ln/An separation. These insights contribute to the development of more effective and selective chelating agents for preferential actinide binding. [ABSTRACT FROM AUTHOR]

In the quest to understand biologically relevant interactions of environmentally detrimental SO2 with host molecules to modulate the electronic properties of the binding sites, we have directly observed the lone pair⋯π interaction between the aromatic ring and nucleophilic O of SO2 (3.11 Å), for the first time to the best of our knowledge, in addition to the interaction between electrophilic S of SO2 and metal-bound thiolate (2.63 Å). [ABSTRACT FROM AUTHOR]

A comprehensive study has been carried out to understand the details of structural modifications of polyallyl diglycol carbonate (PADC) polymer under the effects of different external factors. Synergistic effect of heat treatment with radiation on the polymer structure was studied. Incorporation of a neutral chromophore to understand the structural changes was attempted. Theoretical simulations were applied to get insight into the detailed aspects of structural modifications. Diverse techniques were used to characterize the samples and compare with the results of simulation studies. [ABSTRACT FROM AUTHOR]

A simple, efficient, direct and economical method for the mutual separation of Nd and Pr was developed by the selective dissolution of Nd2O3 from their oxide mixtures in an ionic liquid containing 2‐thenoyltrifluoroacetone (HTTA) resulting in an unprecedented separation factor (βNd/Pr)>500, which is 277 times more than the thus far reported βNd/Pr values. The proposed mechanism was supported by DFT computations. [ABSTRACT FROM AUTHOR]

Fragile hemiaminal ether linkages present in the backbone of koneramines (LROR'), tridentate ligands, bound to copper(II) in stereoselectively self‐assembled syn‐[Cu(LROR')X2] complexes were transformed into sturdy methylene linkages to make corresponding rac‐[Cu(LRH)Cl2] complexes by late‐stage ligand modification after coordination with the retention of coordination sphere. The generality of stereoselective self‐assembly of koneramine complexes is shown by utilising a number of metal ions, anions, amines, alcohols and thiols with complete characterisations. [ABSTRACT FROM AUTHOR]

DFT and ab initio DLPNO-CCSD(T) calculations predict a stable S = 2 six-coordinate FeIV=O species with cucurbit[5]uril (CB[5]) as a ligand ([(CB[5])FeIV=O(H2O)]2+(1)). The strong oxidising capability of 1 far exceeds even that of metalloenzymes such as sMMOs in activating inert substrates such as methane, setting the stage for a new generation of biomimetic catalysts. [ABSTRACT FROM AUTHOR]

The iron carrier human serum transferrin (sTf) is known to transport other metals, including some actinides (An). Radiotoxic An are routinely involved in the nuclear fuel cycle and the possibility of their accidental exposure cannot be ruled out. Understanding An interaction with sTf assumes a greater significance for the development of safe and efficacious chelators for their removal from the blood stream. Here we report several 100 ns equilibrium MD simulations of Cm(III)‐ and Th(IV)‐loaded sTf at various protonation states of the protein to explore the possibility of the two An ions release and speciation. The results demonstrate variation in protonation state of dilysine pair (K206 and K296) and the tyrosine (Y188) residue is necessary for the opening of Cm(III)‐bound protein and the release of the ion. For the tetravalent thorium, protonation of dilysine pair suffices to cause conformational changes of protein. However, in none of the protonation states, Th(IV) releases from sTf because of its strong electrostatic interaction with D63 in the first shell of the sTf binding cleft. Analysis of hydrogen bond, water bridge, and the evaluation of potential of mean forces of the An ions' release from sTf, substantiate the differential behavior of Cm(III) and Th(IV) at endosomal pH. The results provide insight in the regulation of Cm(III) and Th(IV) bioavailability that may prove useful for effective design of their decorporating agents and as well may help the future design of radiotherapy based on tetravalent ions. [ABSTRACT FROM AUTHOR]

Reduction process of the hydrated uranyl cation, [[U[O.sub.2]].sup.2+], by cyctochromes is studied. A catalytic cycle for the enzymatic reduction of uranyl cation is proposed.