Structures and functions of mitochondrial ABC transporters

A small number of physiologically important ATP-binding cassette (ABC) transporters are found in mitochondria. Most are half transporters of the B group forming homodimers and their topology suggests they function as exporters. The results of mutant studies point towards involvement in iron cofactor biosynthesis. In particular, ABC subfamily B member 7 (ABCB7) and its homologues in yeast and plants are required for iron-sulfur (Fe-S) cluster biosynthesis outside of the mitochondria, whereas ABCB10 is involved in haem biosynthesis. They also play a role in preventing oxidative stress. Mutations in ABCB6 and ABCB7 have been linked to human disease. Recent crystal structures of yeast Atm1 and human ABCB10 have been key to identifying substrate-binding sites and transport mechanisms. Combined with in vitro and in vivo studies, progress is being made to find the physiological substrates of the different mitochondrial ABC transporters

Effect of the Iron-containing Filler on the Strength of Concrete

The purpose of present research is to determine the impact of a mixture of river and technogenic sand containing iron compounds in the presence of plasticizers on the strength of fine-grained concretes. As a result of the performed research it was established that the technogenic sand, representing mineral complexes containing iron compounds, interacts with Portland cement minerals and the products of their hydration. The studies we conducted showed the possibility of targeted regulation of the processes of formation of structure of fine-grained concretes by joint application of mineral complex with iron ions, river sand and surface-active substances that are substantially different in the structure of molecules. It was established that using a mixture of river and technogenic sand containing iron compounds in the form of a fine aggregate leads to a significant increase in concrete strength. There is a certain ratio between river sand and the technogenic sand containing iron compounds, which provides concrete with the largest strength. An optimal content of the technogenic sand in a fine aggregate depends on the type and amount of minerals within its structure, and the content of particles with different size. It is demonstrated that the effectiveness of using modern superplasticizers in fine-grained concretes increases considerably with the introduction of mineral complexes containing ions of iron to the compositions of concrete

FLUORESCENT PROPERTIES OF PHENYL - CONTAINING ISOMERS OF PALLADIUM COMPLEXES OF OCTAETHYLPORPHIN IN ACETONITRILE

The fluorimetric measurements of the acetonitrile solutions of palladium complexes of the octaethylporphyrin, 5,10- biphenyl octaethylporphyrin and 5,15-biphenyl octaethylporphyrin at 293 K were performed. Tetraphenylporfin was used in toluene as standards. It was determined that the studied compounds differ in the architecture of peripheral substitution, and as a result in molecular conformation and symmetry, which determine the rates of intramolecular processes of deactivation of electronic excitation energy. It was established that the introduction of two phenyl fragments into the meso-positions of the tetrapyrrole macrocycle of the octaethylporphyrin molecule markedly changes the spectral-luminescent properties of their palladium complexes. The compound with the adjacent arrangement of phenyl fragments of 5,10-diphenylctaethylporphyrin is characterized by concentrated steric effects in the region of one quadrant of the macrocycle containing two phenyl groups and the pyrrole fragment located between them. This arrangement of phenyl fragments leads to the formation of an asymmetrically distorted saddle-shaped conformer, as evidenced by the bathochromic shift of the bands in the electronic absorption spectrum by 495 cm–1. The quantum yield of S1→S0 fluorescence decreases slightly to 4.6·10-3, which is explained by the formation of a new competing non-radiative deactivation channel — the internal S1→S0 conversion, which is characteristic of distorted saddle-shaped macrocycle. When phenyl groups at opposite meso-positions of the 5.15-diphenyl octaethylporphyrin macrocycle flanked by alkyl groups in the Cb positions of the pyrrole rings, a conformer is formed with a macrocycle elongated along the Cm-Cm axis. This is probably due to the stricter molecular structure of this conformer compared to palladium octaethylporphyrin and the absence of conformational dynamics in the S1 excited state. As a result, the bathochromic shift of the bands in the electronic absorption spectrum of 5.15 – diphenyl octaethylporphyrin is less than 100 cm-1 and the quantum yield of S1→S0 fluorescence is almost equal to the quantum yield of the palladium complex of octaethylporphyrin - 5.4·10-3, which is probably due to the low non-radiative internal S1→S0 conversion for the 5.15-diphenyl octaethylporphyrin compared to the 5.10-diphenyl octaethylporphyrin.</jats:p