Solvent-exposed tryptophans probe the dynamics at protein surfaces

The dynamics of single tryptophan (W) side chain of protease subtilisin Carlsberg (SC) and myelin basic protein (MBP) were used for probing the surface of these proteins. The W side chains are exposed to the solvent, as shown by the extent of quenching of their fluorescence by KI. Time-resolved fluorescence anisotropy measurements showed that the rotational motion of W is completely unhindered in the case of SC and partially hindered in the case of MBP. The rotational correlation time (Φ) associated with the fast local motion of W did not scale linearly with the bulk solvent viscosity (η) in glycerol-water mixtures. In contrast, Φ values of either W side chains in the denatured proteins or the free W scaled almost linearly with η, as expected by the Stokes-Einstein relationship. These results were interpreted as indicating specific partitioning of water at the surface of the proteins in glycerol-water mixtures

High-salt diet suppresses autoimmune demyelination by regulating the blood-brain barrier permeability

Sodium chloride, "salt," is an essential component of daily food and vitally contributes to the body's homeostasis. However, excessive salt intake has often been held responsible for numerous health risks associated with the cardiovascular system and kidney. Recent reports linked a high-salt diet (HSD) to the exacerbation of artificially induced central nervous system (CNS) autoimmune pathology through changes in microbiota and enhanced T(H)17 cell differentiation [M. Kleinewietfeld et al., Nature 496, 518-522 (2013); C. Wu et al., Nature 496, 513-517 (2013); N. Wilck et al., Nature 551, 585-589 (2017)]. However, there is no evidence that dietary salt promotes or worsens a spontaneous autoimmune disease. Here we show that HSD suppresses autoimmune disease development in a mouse model of spontaneous CNS autoimmunity. We found that HSD consumption increased the circulating serum levels of the glucocorticoid hormone corticosterone. Corticosterone enhanced the expression of tight junction molecules on the brain endothelial cells and promoted the tightening of the blood-brain barrier (BBB) thereby controlling the entry of inflammatory T cells into the CNS. Our results demonstrate the multifaceted and potentially beneficial effects of moderately increased salt consumption in CNS autoimmunity.We thank the Mass Spectrometry and NGS Core Facilities at the Max Planck Institute of Biochemistry for performing sample analysis for proteomics and mRNA-seq experiments

Combined Lab-on-a-Chip and microarray approach for biomolecular interaction sensing using surface plasmon resonance imaging

Surface plasmon resonance imaging (SPR) is a well-established label-free detection technique for real-time biomolecular interaction measurements. An integrated LOC sensing system with fluidic control for sample movement to specific locations on microarray surface in combination with SPR imaging is demonstrated by the measurements of human IgG and anti-IgG interactions from 24 patterned regions.\u

Structure is lost incrementally during the unfolding of barstar

Coincidental equilibrium unfolding transitions observed by multiple structural probes are taken to justify the modeling of protein unfolding as a two-state, N⇋U, cooperative process. However, for many of the large number of proteins that undergo apparently two-state equilibrium unfolding reactions, folding intermediates are detected in kinetic experiments. The small protein barstar is one such protein. Here the two-state model for equilibrium unfolding has been critically evaluated in barstar by estimating the intramolecular distance distribution by time-resolved fluorescence resonance energy transfer (TR-FRET) methods, in which fluorescence decay kinetics are analyzed by the maximum entropy method (MEM). Using a mutant form of barstar containing only Trp 53 as the fluorescence donor and a thionitrobenzoic acid moiety attached to Cys 82 as the fluorescence acceptor, the distance between the donor and acceptor has been shown to increase incrementally with increasing denaturant concentration. Although other probes, such as circular dichroism and fluorescence intensity, suggest that the labeled protein undergoes two-state equilibrium unfolding, the TR-FRET probe clearly indicates multistate equilibrium unfolding. Native protein expands progressively through a continuum of native-like forms that achieve the dimensions of a molten globule, whose heterogeneity increases with increasing denaturant concentration and which appears to be separated from the unfolded ensemble by a free energy barrier

Antibacterial activity of diff erent solvent extracts of Caulerpa chemnitzia (Esper) J.V. Lamououx, from Mandapam, Gulf of Mannar Southeast Coast, Tamil Nadu, India

Phytochemical analyses and in vitro antibacterial activity of different extracts of hexane, chloroform, ethyl acetate,acetone, and methanol extracts of green algae, Caulerpa chemnitzia (Esper) J.V. Lamououx, against Bacillussubtilis, Streptococcus pyogenes, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris,Pseudomonas aeruginosa, Salmonella typhimurium, Shigella flexneri, and Vibrio cholerae. The extent of theinhibitory zone, Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) weredetermined. The ethyl acetate extract of C. chemnitzia showed the presence of phytochemicals, terpenoids,tannins and phenolic compounds strongly than the other solvent extracts. The mean zone of inhibition producedby the extracts in agar diffusion assays against the tested bacterial strains ranged from 7.1 to 13.6 mm. The MICwas between 125 and 500 μg/mL while the MBC were between 250 and 1000 μg/mL. The highest mean zoneof inhibition (13.6 mm) and the lowest MIC (125 μg/mL) and MBC (250 μg/mL) values were observed in ethylacetate extract against B. subtilis. These findings suggest that the ethyl acetate extract of C. chemnitzia can beused as an antibacterial substance for the treatment of bacteria causing acquired infection

Screening of phytochemical and antibacterial potential of diff erent organic solvent extracts of Stoechospermum marginatum (Ag) Kutz. from Manappad coast, Tuticorin District, South India

The antibacterial activity of different extracts of hexane, chloroform, ethyl acetate, acetone and methanol extractof a brown alga, Stoechospermum marginatum (Ag) Kutz. against Bacillus subtilis, Streptococcus pyogenes,Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Pseudomonas aeruginosa, Salmonellatyphimurium, Shigella flexneri and Vibrio cholerae. The extent of the inhibitory zone, Minimum InhibitoryConcentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined. The ethyl acetateextract of S. marginatum showed the highest antibacterial activity against all the bacterial strains tested thanthe other extracts. The mean zones of inhibition produced by the extracts in agar diffusion assays against thetested bacterial strains ranged from 7.1 to 18.1 mm. The MIC were between 125 and 500 μg/ml, while theMBC were between 250 and 1000 μg/ml. The ethyl acetate extract of S. marginatum showed the presenceof terpenoids, tannins, phenolic compounds and steroids strongly than the other solvent extracts. The highestmean of zone inhibition (18.1 mm) was observed in the ethyl acetate extract of S. marginatum against B. subtilis.These finding suggest that the ethyl acetate extract of S. marginatum can be used as an antibacterial substancefor the treatment of bacterial infections

Solvent-Exposed Tryptophans Probe the Dynamics at Protein Surfaces

ABSTRACT The dynamics of single tryptophan (W) side chain of protease subtilisin Carlsberg (SC) and myelin basic protein (MBP) were used for probing the surface of these proteins. The W side chains are exposed to the solvent, as shown by the extent of quenching of their fluorescence by KI. Time-resolved fluorescence anisotropy measurements showed that the rotational motion of W is completely unhindered in the case of SC and partially hindered in the case of MBP. The rotational correlation time () associated with the fast local motion of W did not scale linearly with the bulk solvent viscosity () in glycerol-water mixtures. In contrast, values of either W side chains in the denatured proteins or the free W scaled almost linearly with , as expected by the Stokes-Einstein relationship. These results were interpreted as indicating specific partitioning of water at the surface of the proteins in glycerol-water mixtures

Accumulation of trace metals in green mussel Perna viridis in the shellfish harvesting environment along southern Karnataka coast

The levels of trace metals, Cd, Pb, Cu, Zn, Ni and Fe in seawater and their bioaccumulation in green mussel Perna viridis were examined in two shellfish harvesting environments, Someshwara and Surathkal, along the southern Karnataka coast. In seawater, the concentration of trace metals analysed were below the levels causing harmful effects on the larvae and adult mussels, set by the European Council Directive 79/923/EEC. The Fe, Ni, Cd and Zn levels in mussel tissue from Surathkal were relatively higher when compared to that of mussel tissue samples from Someshwara while Cu and Pb levels were lower. The mean tissue concentrations of trace metals in the soft tissue of P. viridis from shellfish waters were found to be safe and below the permissible concentrations for seafood (US FDA and WHO) as well as EU limits in marine products