Alpha-helical regions of the protein molecule as organic nanotubes

An α-helical region of protein molecule was considered in a model of nanotube. The molecule is in conditions of quantum excitations. Such model corresponds to a one-dimensional molecular nanocrystal with three molecules in an elementary cell at the presence of excitation. For the analysis of different types of conformational response of the α-helical area of the protein molecule on excitation, the nonlinear response of this area to the intramolecular quantum excitation caused by hydrolysis of adenosine triphosphate (ATP) is taken into account. It has been established that in the simplest case, three types of excitation are realized. As estimates show, each of them ‘serves’ different kinds of protein. The symmetrical type of excitation, most likely, is realized in the reduction of traversal-striped skeletal muscles. It has the highest excitation energy. This well protects from casual actions. Antisymmetric excitations have intermediate energy (between symmetrical and asymmetrical). They, most likely, are realized in membranous and nucleic proteins. It is shown that the conformational response of the α-helical region of the protein is (in angstroms) a quantity of order N _c /5, where N _c is the number of spiral turns. For the number of turns typical in this case: N _c  ~ 10, displacement compounds are a quantity of order 2 Å. It qualitatively corresponds to observable values. Asymmetrical excitations have the lowest energy. Therefore, most likely, they are realized in enzymatic proteins. It was shown that at this type of excitation, the bending of the α-helix is formally directed to the opposite side with respect to the antisymmetric excitations. Also, it has a greater value than the antisymmetric case for N _c  ≤ 14 and smaller for N _c  > 14.

PACS

92C05

MCS

36.20.Ey     

Effect of Hypergravity on the Level of Heat Shock Proteins 70 and 90 in Pea Seedlings

Exposure to hypergravity induces significant changes in gene expression of plants which are indicative of stress conditions. A substantial part of the general stress response is up-regulation of heat shock proteins (Hsp) which function as molecular chaperones. The objective of this research was to test the possible changes in the Hsp70 and Hsp90 level in response to short-term hypergravity exposure. In this study 5-day-old etiolated pea seedlings were exposed to centrifuge-induced hypergravity (3–14 g) for 15 min and 1 h and a part of the seedlings was sampled at 1.5 and 24 h after the exposures. Western blot analysis showed time-dependent changes in Hsp70 and Hsp90 levels: an increase under hypergravity and a tendency towards recovery of the normal content during re-adaptation. The quantity and time of their expression was correlated with the g-force level. These data suggest that short-term hypergravity acts as a stress which could increase the risk of protein denaturation and aggregation. Molecular chaperons induced during the stress may have an essential role in counteracting this risk.     

Removing of fulvic acids by ozonation and biological active carbon filtration

It was studied the effect of the content of biodegradable organic carbon (BDOC) after the processes of aeration and ozonation of the fulvic acid (FA) solutions on the efficiency of its adsorption and biofiltration. It was found that the change of free energy of adsorption of the FA oxidation products correlated with the part of biodegradable organic carbon in total organic carbon content. Predicting the effectiveness of NOM solutions ozonation before filtration through BAC is more appropriate by determining the value of the free adsorption energy. It was established that ozonation of FA solutions with high initial BDOC content by ozone doses that are economically and technologically acceptable, leads to a decrease in the BDOC value. Ozonation of FA solutions leads to equalization of the adsorption ability of FA fractions and increases the adsorption energy of FA in most investigated systems with a high initial BDOC content.     

The stress protein level under clinorotation in context of the seedling developmental program and the stress response

Heat-shock proteins (HSP70 and HSP90) are present in plant cells under the normal growth conditions. At the same time, a variety of environmental disruptions results in their rapid synthesis as a substantial part of adaptation. HSP amounts can be indicative of a cellular stress level. Altered gravity (clinorotation) is unnatural for plants, so it may be a kind of stress. The aim of this study was to analyze the influence of horizontal clinorotation on the HSP70 and HSP90 level during seedling development. Pea (Pisum sativum L.) seedlings grown for 3 days from seed imbibitions in stationary control and under slow clinorotation (2 rpm) are used for this investigation. Western blot analysis indicated that HSP70 and HSP90 were abundant in the embryos of dry seeds and their amount decreased significantly during seed germination. But under horizontal clinorotation, their level in seedlings remained higher compared to the control. Furthermore, a comparison of the influence of horizontal and vertical clinorotation on the HSP level was carried out. On the ELISA data, HSP70 and HSP90 amounts in the 3-day old seedlings were higher after horizontal clinorotation than after vertical. The obtained data show an increased HSP70 and HSP90 level in pea seedlings under clinorotation. Both, rotation and change in the cell position relatively to a gravity vector affect the HSP level.     

The influence of lead nanoparticles on the morpho‐functional changes of rat liver during the postexposure period

Lead as any heavy metals may be found in soil, water, air, and is used in everyday life. Once in the body, it causes toxic effect, making the liver, which is one of the main organs of detoxification, suffer. Recently, the study of the action of not only ionic forms of lead, but also its nanoparticles, has become topical. The study aims at determining changes in the liver of rats and biochemical changes in their blood both at late term of exposure to nanoparticles of lead compounds and in the post‐exposure period. The study was performed on 120 male rats of Wistar line, which were divided into two series, each series containing four groups. The first and the second groups of animals were intraperitoneally injected with colloidal solution of nanoparticles of lead sulfide of 10 and 30 nm in size, and the third group were intraperitoneally injected with a solution of lead nitrate. The fourth group of animals served as control. In the first series, the investigated substances were administered 60 times within 12 weeks. In the second series, after 60‐fold administration of the investigated substances, the exposure was discontibued and animals were observed for 6 weeks—overall duration of 18 weeks. Histological, morphometrical and biochemical methods were used. The body weight was reduced in the rats exposed to PbS_nano1 at week 12 of experiment and in rats exposed to both PbS_nano1 and Pb(NO₃)₂ in the second series. Absolute liver weight increased at week 12 of experiment in all experimental groups. In the second series this value almost reached that of the control level. Relative liver weight in the animals of all experimental groups was higher than that in the control at week 12 of experiment. In the second series this value remained higher in rats exposed to PbS_nano1. After 12 weeks of exposure dystrophic changes in the liver were found in all experimental groups. At week 6 after the exposure (the second series) destructive changes in the liver decreased. Total protein, albumin, glucose, total lipids, cholesterol, triglycerides content in blood serum corresponded with morphological data. The experiment has demonstrated that the 12 weeks long exposure to lead nanoparticles had harmful effect on the liver. Within the postexposure 6‐weeks period structural changes in the liver and biochemical changes in blood serum decreased. Biochemical changes in blood serum corresponded to the morphological data. By many parameters PbS_nano1 had more pronounced harmful effect. Toxicity of PbS_nano2 and Pb(NO₃)₂ were comparable.     

Self-disintegrating slag for electroslag remelting of hollow ingot

A new slag susceptible to self-disintegration in the solid state due to formation of dicalcium silicate (2CaOSiO₂) was developed. This compound reduces the thermodynamic activity of silica in a slag and, consequently, decreases silicon reduction and its transition to metal in the electroslag remelting process.