Proton leap: shuttling of protons onto benzonitrile

The detailed description of chemical transformations in the interstellar medium allows deciphering the origin of a number of small and medium - sized organic molecules. We present density functional theory analysis of proton transfer from the trihydrogen cation and the ethenium cation to benzonitrile, a recently discovered species in the Taurus Molecular Cloud 1. Detailed energy transformations along the reaction paths were analyzed using the interacting quantum atoms methodology, which elucidated how the proton carrier influences the lightness to deliver the proton to benzonitrile's nitrogen atom. The proton carriers' deformation energy represents the largest destabilizing effect, whereas a proton's promotion energy, the benzonitrile-proton Coulomb attraction, as well as non-classical benzonitrile-proton and carrier-proton interaction are the dominant stabilizing energy components. As two ion-molecule reactions proceed without energy barriers, rate constants were estimated using the classical capture theory and were found to be an order of magnitude larger for the reaction with the trihydrogen cation compared to that with the ethenium cation (∼10^-8 and 10^-9 cm³ s^-1, respectively). These results were obtained both with quantum chemical and ab initio molecular dynamics simulations (the latter performed at 10 K and 100 K), confirming that up to 100 K both systems choose energetically undemanding routes by tracking the corresponding minimum energy paths. A concept of a turning point is introduced, which is an equivalent to the transition state in barrierless reactions.

Glucocorticoid receptor-Hsp90 interaction in the liver cytosol of cadmium-intoxicated rats

The influence of cadmium on the rat liver glucocorticoid receptor (GR) binding capacity, on the cytosolic level of 90 kDa heat shock protein (Hsp90), and on the association of the two proteins was investigated. The results showed that the mode of metal application led to diverse alterations in hormone binding to the GR. Reduction of the GR binding capacity observed after in vitro treatment was proportional to the applied metal concentrations. In animals administered different doses of cadmium, GR binding capacity was not reduced, except in those that received the highest dose. A concomitant elevation of Hsp90 level was detected both in the cytosol and within the GR untransformed heterocomplexes. The results suggest that cadmium-induced reduction of the GR binding capacity seen in vitro was prevented in intact animals by the elevated level of Hsp90 within the GR heterocomplexes.