Raman spectra of nanodiamonds: New treatment procedure directed for improved raman signal marker detection

Detonation nanodiamonds (NDs) have shown to be promising agents in several industries, ranging from electronic to biomedical applications. These NDs are characterized by small particle size ranging from 3 to 6 nm, while having a reactive surface and a stable inert core. Nanodiamonds can exhibit novel intrinsic properties such as fluorescence, high refractive index, and unique Raman signal making them very attractive imaging agents. In this work, we used several nanodiamond preparations for Raman spectroscopic studies. We exposed these nanodiamonds to increasing temperature treatments at constant heating rates (425-575°C) aiding graphite release. We wanted to correlate changes in the nanodiamond surface and properties with Raman signal which could be used as a detection marker. These observations would hold potential utility in biomedical imaging applications. First, the procedure of optimal linear smoothing was applied successfully to eliminate the high-frequency fluctuations and to extract the smoothed Raman spectra. After that we applied the secondary Fourier transform as the fitting function based on some significant set of frequencies. The remnant noise was described in terms of the beta-distribution function. We expect this data treatment to provide better results in biomolecule tracking using nanodiamond base Raman labeling. © 2013 Raoul R. Nigmatullin et al

Differences in the Pathways of Proteins Unfolding Induced by Urea and Guanidine Hydrochloride: Molten Globule State and Aggregates

It was shown that at low concentrations guanidine hydrochloride (GdnHCl) can cause aggregation of proteins in partially folded state and that fluorescent dye 1-anilinonaphthalene-8-sulfonic acid (ANS) binds with these aggregates rather than with hydrophobic clusters on the surface of protein in molten globule state. That is why the increase in ANS fluorescence intensity is often recorded in the pathway of protein denaturation by GdnHCl, but not by urea. So what was previously believed to be the molten globule state in the pathway of protein denaturation by GdnHCl, in reality, for some proteins represents the aggregates of partially folded molecules

Folding of poly-amino acids and intrinsically disordered proteins in overcrowded milieu induced by pH change

pH-induced structural changes of the synthetic homopolypeptides poly-E, poly-K, poly-R, and intrinsically disordered proteins (IDPs) prothymosin alpha (ProT alpha) and linker histone H1, in concentrated PEG solutions simulating macromolecular crowding conditions within the membrane-less organelles, were characterized. The conformational transitions of the studied poly-amino acids in the concentrated PEG solutions depend on the polymerization degree of these homopolypeptides, the size of their side chains, the charge distribution of the side chains, and the crowding agent concentration. The results obtained for poly-amino acids are valid for IDPs having a significant total charge. The overcrowded conditions promote a significant increase in the cooperativity of the pH-induced coil-alpha-helix transition of ProTa and provoke histone H1 aggregation. The most favorable conditions for the pH-induced structural transitions in concentrated PEG solutions are realized when the charged residues are grouped in blocks, and when the distance between the end of the side group carrying charge and the backbone is small. Therefore, the block-wise distribution of charged residues within the IDPs not only plays an important role in the liquid-liquid phase transitions, but may also define the expressivity of structural transitions of these proteins in the overcrowded conditions of the membrane-less organelles. (C) 2018 Elsevier B.V. All rights reserved.Peer reviewe

Spectral Properties of Thioflavin T and Its Complexes with Amyloid Fibrils

Comparative analysis of the absorption and fluorescence spectra and fluorescence excitation spectra of thioflavin T (ThT) in various solvents and in the composition of amyloid fibrils has shown that ThT, when excited in the region of the long-wavelength absorption band, fluoresces in the spectral region with a maximum at 478–484 nm. The appearance in aqueous and alcohol solutions of a fluorescence band with a maximum near 440 nm has been attributed to the presence in the composition of the ThT preparations of an impurity with an absorption band in the 340–350-nm range. The literature data showing that in glycerol ThT has a wide fluorescence spectrum with two maxima are due to the artifact connected with the use of a high concentration of the dye. It has been suggested that the cause of the low quantum yield of ThT aqueous and alcohol solutions is the breakage of the system of conjugated bonds due to the reorientation of the benzothiozole and benzaminic rings of ThT in the excited state with respect to one another. The main factor determining the high quantum yield of fluorescence of ThT incorporated in fibrils is the steric restriction of the rotation of the rings about one another under these conditions. The suggestions made have been verified by the quantum-chemical calculation of the ThT molecule geometry in the ground and excited states

Substantiation of approaches to the correction of lipid metabolism disorders and non-alcoholic fatty liver disease in children with exogenous obesity

BACKGROUND: According to the involvement of oxidative stress in the pathogenesis of obesity, the plasma level of coenzyme q10 in the correlation relationship with lipid metabolism disorders and functional liver state is of interest to study.AIM: Substantiation of approaches to the correction of lipid metabolism disorders and non-alcoholic fatty liver disease in children with exogenous obesity based on the content of coenzyme Q10 and its relationship with lipid profile and liver enzymes.MATERIALS AND METHODS: The single-center cross-sectional study enlisted the control (n=32, -1.0≤BMI SD score ≤+2.0) and obese (n=40, BMI SD score>+2.0) groups of children with the mean age of 12 yr. In all children BMI, lipidogram, liver enzymes (ALT and AST), plasma coenzyme Q10 and liver ultrasound examination were assessed.RESULTS: Patients of both groups were comparable (p> 0.05) in age and gender. The level of coenzyme Q10 in the compared groups was comparable (p> 0.05) and did not differ in patients with different degrees of obesity. According to the results of the study of the lipid profile in the obese children, the level of HDL was lower, and the level of LDL was higher than that in control group. The highest value of HDL was obtained in the patients with the 1st degree of obesity and the highest level of triglycerides — in the patients with the 4th degree of obesity. The control group demonstrated moderate correlations between endogenous coenzyme Q10 and total cholesterol (r=0.474, p=0.009) which persists in patients with the first degree of obesity (r = 0.548, p = 0.035). There was no difference in AST in the study groups, however, the main group demonstrated elevated ALT and ALT/AST ratio (p <0.001). The highest ALT and ALT / AST ratio were observed in patients with greatest degree of obesity. Eighteen obese children (45%) had ALT / AST ratio ≥1 (in the control group –one patient (3%) (p <0.001), while fourteen patients showed liver enlargement and structure change according to ultrasound (80%). The control group demonstrated moderate correlations between endogenous coenzyme Q10 and total cholesterol (r=0.474, p=0.009) and between coenzyme Q10 and ALT / AST ratio (r=0.412, p=0.023) . In the obese group there was correlation between AI and ALT / AST (r = 0.436, p = 0.006) and in patients with the 1st degree of obesity — between also coenzyme Q10 and ALT (r = 0.875, p <0.001).CONCLUSION: The disturbances in adequate control of cholesterol by coenzyme Q10 in obese children possibly confirming the involvement of oxidative stress in the pathogenesis of dyslipidemia and non-alcoholic fatty liver disease can serve as indication to use coenzyme Q10 in order to correct these complications

Characterization of a Deswapped Triple Mutant Bovine Odorant Binding Protein

The stability and functionality of GCC-bOBP, a monomeric triple mutant of bovine odorant binding protein, was investigated, in the presence of denaturant and in acidic pH conditions, by both protein and 1-aminoanthracene ligand fluorescence measurements, and compared to that of both bovine and porcine wild type homologues. Complete reversibility of unfolding was observed, though refolding was characterized by hysteresis. Molecular dynamics simulations, performed to detect possible structural changes of the monomeric scaffold related to the presence of the ligand, pointed out the stability of the β-barrel lipocalin scaffold

Dissimilarity in the Folding of Human Cytosolic Creatine Kinase Isoenzymes

Creatine kinase (CK, EC 2.7.3.2) plays a key role in the energy homeostasis of excitable cells. The cytosolic human CK isoenzymes exist as homodimers (HMCK and HBCK) or a heterodimer (MBCK) formed by the muscle CK subunit (M) and/or brain CK subunit (B) with highly conserved three-dimensional structures composed of a small N-terminal domain (NTD) and a large C-terminal domain (CTD). The isoforms of CK provide a novel system to investigate the sequence/structural determinants of multimeric/multidomain protein folding. In this research, the role of NTD and CTD as well as the domain interactions in CK folding was investigated by comparing the equilibrium and kinetic folding parameters of HMCK, HBCK, MBCK and two domain-swapped chimeric forms (BnMc and MnBc). Spectroscopic results indicated that the five proteins had distinct structural features depending on the domain organizations. MBCK BnMc had the smallest CD signals and the lowest stability against guanidine chloride-induced denaturation. During the biphasic kinetic refolding, three proteins (HMCK, BnMc and MnBc), which contained either the NTD or CTD of the M subunit and similar microenvironments of the Trp fluorophores, refolded about 10-fold faster than HBCK for both the fast and slow phase. The fast folding of these three proteins led to an accumulation of the aggregation-prone intermediate and slowed down the reactivation rate thereby during the kinetic refolding. Our results suggested that the intra- and inter-subunit domain interactions modified the behavior of kinetic refolding. The alternation of domain interactions based on isoenzymes also provides a valuable strategy to improve the properties of multidomain enzymes in biotechnology

The concept of device for the prevention of negative exposure of sun radiation on human skin

The article deals the concept of device for the prevention of negative exposure of sun radiation. We described the expected functions of the device. The program for calculation the individual dose of threshold UV radiation was developed.В статье описана концепция устройства для профилактики негативного воздействия солнечного излучения, Описан предполагаемый функционал устройства. Разработана программа для определения индивидуальной дозы порогового УФ-излучения