Protein‐Based Capacitive Biosensors: a New Tool for Structure‐Activity Relationship Studies

The present work reports a new application of a protein‐based capacitive biosensor as an in vitro assay for the selectivity study of the bacterial periplasmic protein MerP and four MerP variants. The modified MerP proteins were produced by site‐directed mutagenesis of the heavy metal associated motif (HMA). The MerP and modified MerPs selectivity for copper, zinc, cadmium and mercury bivalent ions were investigated and compared. The variations in the proteins affinity were related to the primary structure of the HMA motifs. Key amino acids for copper coordination of metalloproteins that contain the metal binding sequence Gly‐Met‐Thr‐Cys‐xxx‐xxx‐Cys were identified. The results brought insights valid for Menkes and Wilson ATPases. The protein‐based capacitive biosensors were a simple and useful tool for studying structure‐activity relationships of proteins.     

Simultaneous determination of U and Th by delayed fission neutron technique based on neutron generator

A method for simultaneous determination of uranium and thorium based on the deviation of their fission cross-section curves has been developed. Using a D-T neutron generator two different neutron spectra were produced with and without moderator around the target. The detection limits were found to be 0.044 mg and 0.25 mg in the presence of a moderator, while for fast neutrons 0.017 mg and 0.037 mg for uranium and thorium, respectively.This work was supported in part by the Ministry of Higher Education and the Hungarian Academy of Sciences.     

Quantum Nuclear Delocalization and its Rovibrational Fingerprints

Quantum mechanics dictates that nuclei must undergo some delocalization. In this work, emergence of quantum nuclear delocalization and its rovibrational fingerprints are discussed for the case of the van der Waals complex . The equilibrium structure of is planar and T-shaped, one He atom solvating the quasi-linear He−H⁺−He core. The dynamical structure of , in all of its bound states, is fundamentally different. As revealed by spatial distribution functions and nuclear densities, during the vibrations of the molecule the solvating He is not restricted to be in the plane defined by the instantaneously bent chomophore, but freely orbits the central proton, forming a three-dimensional torus around the chromophore. This quantum delocalization is observed for all vibrational states, the type of vibrational excitation being reflected in the topology of the nodal surfaces in the nuclear densities, showing, for example, that intramolecular bending involves excitation along the circumference of the torus.