Glycyl-alanyl-histidine protects PC12 cells against hydrogen peroxide toxicity

Background

Peptides with cytoprotective functions, including antioxidants and anti-infectives, could be useful therapeutics. Carnosine, β-alanine-histidine, is a dipeptide with anti-oxidant properties. Tripeptides of Ala-His-Lys, Pro-His-His, or Tyr-His-Tyr are also of interest in this respect.

Results

We synthesized several histidine-containing peptides including glycine or alanine, and tested their cytoprotective effects on hydrogen peroxide toxicity for PC12 cells. Of all these peptides (Gly-His-His, Ala-His-His, Ala-His-Ala, Ala-Ala-His, Ala-Gly-His, Gly-Ala-His (GAH), Ala-His-Gly, His-Ala-Gly, His-His-His, Gly-His-Ala, and Gly-Gly-His), GAH was found to have the strongest cytoprotective activity. GAH decreased lactate dehydrogenase (LDH) leakage, apoptosis, morphological changes, and nuclear membrane permeability changes against hydrogen peroxide toxicity in PC12 cells. The cytoprotective activity of GAH was superior to that of carnosine against hydrogen peroxide toxicity in PC12 cells. GAH also protected PC12 cells against damage caused by actinomycin D and staurosporine. Additionally, it was found that GAH also protected SH-SY5Y and Jurkat cells from damage caused by hydrogen peroxide, as assessed by LDH leakage.

Conclusion

Thus, a novel tripeptide, GAH, has been identified as having broad cytoprotective effects against hydrogen peroxide-induced cell damage.

     

Isolation of ethanol from its aqueous solution by liquid phase adsorption and gas phase desorption using molecular sieving carbon

A novel bioethanol separation process was proposed in this study employing molecular sieving carbon (MSC) as an adsorbent, whose pore diameter is close to molecular size of ethanol. In the proposed process, fermentation broth is first introduced to the adsorption bed packed with MSC. In this step, ethanol is selectively adsorbed onto MSC, with highly enriching ethanol in the micropore of MSC. Subsequently, the concentrated ethanol is desorbed from MSC to gaseous phase, resulting in further purification of ethanol owing to a considerable difference in desorption rate between water and ethanol; Because of molecular sieving effect of MSC, the desorption rate of ethanol is much smaller than that of water. To establish this process, adsorption equilibrium and kinetics of ethanol on various MSCs were investigated in aqueous phase as the first step. Also, desorption kinetics of ethanol and water in gaseous phase were investigated. As a result, it was suggested that highly concentrated ethanol could be obtained with high recovery ratio through these simple operations, meaning the proposed process is quite promising.     

Inverted micelle formation of cell-penetrating peptide studied by coarse-grained simulation: importance of attractive force between cell-penetrating peptides and lipid head group

Arginine-rich peptide and Antennapedia are cell-penetrating peptides (CPPs) which have the ability to permeate plasma membrane. Deformation of the plasma membrane with CPPs is the key to understand permeation mechanism. We investigate the dynamics of CPP and the lipid bilayer membrane by coarse-grained simulation. We found that the peptide makes inverted micelle in the lipid bilayer membrane, when the attractive potential between the peptide and lipid heads is strong. The inverted micelle is formed to minimize potential energy of the peptide. For vesicle membrane, the peptide moves from the outer vesicle to the inner vesicle through the membrane. The translocation of the peptide suggests inverted micelle model as a possible mechanism of CPPs.     

Model study of CO inhibition of [NiFe]hydrogenase

We propose a modified mechanism for the inhibition of [NiFe]hydrogenase ([NiFe]H(2)ase) by CO. We present a model study, using a NiRu H(2)ase mimic, that demonstrates that (i) CO completely inhibits the catalytic cycle of the model compound, (ii) CO prefers to coordinate to the Ru(II) center rather than taking an axial position on the Ni(II) center, and (iii) CO is unable to displace a hydrido ligand from the NiRu center. We combine these studies with a reevaluation of previous studies to propose that, under normal circumstances, CO inhibits [NiFe]H(2)ase by complexing to the Fe(II) center.     

Single-component nanodiscs via the thermal folding of amphiphilic graft copolymers with the adjusted flexibility of the main chain

Nanodiscs have attracted considerable attention as structural scaffolds for membrane-protein research and as biomaterials in e.g. drug-delivery systems. However, conventional disc-fabrication methods are usually laborious, and disc fabrication via the self-assembly of amphiphiles is difficult. Herein, we report the formation of polymer nanodiscs based on the self-assembly of amphiphilic graft copolymers by adjusting the persistence length of the main chain. Amphiphilic graft copolymers with a series of different main-chain persistence lengths were prepared and these formed, depending on the persistence length, either rods, discs, or vesicles. Notably, polymer nanodiscs were formed upon heating a chilled polymer solution without the need for any additives, and the thus obtained nanodiscs were used to solubilize a membrane protein during cell-free protein synthesis. Given the simplicity of this disc-fabrication method and the ability of these discs to solubilize membrane proteins, this study considerably expands the fundamental and practical scope of graft-copolymer nanodiscs and demonstrates their utility as tools for studying the structure and function of membrane proteins.

A strategy for the fabrication of nanodiscs via the self-assembly of thermoresponsive amphiphilic graft copolymers is demonstrated.     

International journal of computational fluid dynamics real-time prediction of unsteady flow based on POD reduced-order model and particle filter

An integrated method consisting of a proper orthogonal decomposition (POD)-based reduced-order model (ROM) and a particle filter (PF) is proposed for real-time prediction of an unsteady flow field. The proposed method is validated using identical twin experiments of an unsteady flow field around a circular cylinder for Reynolds numbers of 100 and 1000. In this study, a PF is employed (ROM-PF) to modify the temporal coefficient of the ROM based on observation data because the prediction capability of the ROM alone is limited due to the stability issue. The proposed method reproduces the unsteady flow field several orders faster than a reference numerical simulation based on Navier–Stokes equations. Furthermore, the effects of parameters, related to observation and simulation, on the prediction accuracy are studied. Most of the energy modes of the unsteady flow field are captured, and it is possible to stably predict the long-term evolution with ROM-PF.     

Ultrafast Encapsulation of Metal Nanoclusters into MFI Zeolite in the Course of Its Crystallization: Catalytic Application for Propane Dehydrogenation

Encapsulating metal nanoclusters into zeolites combines the superior catalytic activity of the nanoclusters with high stability and unique shape selectivity of the crystalline microporous materials. The preparation of such bifunctional catalysts, however, is often restricted by the mismatching in time scale between the fast formation of nanoclusters and the slow crystallization of zeolites. We herein demonstrate a novel strategy to overcome the mismatching issue, in which the crystallization of zeolites is expedited so as to synchronize it with the rapid formation of nanoclusters. The concept was demonstrated by confining Pt and Sn nanoclusters into a ZSM-5 (MFI) zeolite in the course of its crystallization, leading to an ultrafast, in situ encapsulation within just 5 min. The Pt/Sn-ZSM-5 exhibited exceptional activity and selectivity with stability in the dehydrogenation of propane to propene. This method of ultrafast encapsulation opens up a new avenue for designing and synthesizing composite zeolitic materials with structural and compositional complexity.     

Inelastic scattering on 12Be and disappearance of the N = 8 magic number

Experimental studies on in-beam γ-ray spectroscopy using a ¹²Be radioactive beam are presented. Inelastic scattering of the neutron-rich ¹²Be nucleus on ²⁰⁸Pb, ¹²C, and (CH₂)_n targets has been studied by measuring de-excitation γ-rays in coincidence with scattered particles. The level schemes and transition probabilities are determined for low-lying excited states in ¹²Be. The present paper presents a brief review of the spectroscopic results, which may be associated with the N = 8 shell quenching near the drip line. Received: 1 May 2001 / Accepted: 4 December 2001     

Correction method for X-ray fluorescent determination of chromium in high-alloy steels and nickel-base alloys

Summary A new interelement correction method has been developed for the X-ray fluorescent determination of chromium in high-alloy steels and nickel-base alloys. The calibration equation which was derived from the JIS (Japanese Industrial Standards) model is applicable over wide ranges of compositions by preparation of only Fe-Cr binary standards.The new approach gave better accuracy than that based on Rasberry-Heinrich correction model. The accuracies (_d) were 0.08% for high-alloy steels and 0.14% for nickel-base alloys.

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Korrekturmethode für die röntgenfluorescenzspektrometrische Bestimmung von Chrom in hochlegierten Stählen und Nickellegierungen

Zusammenfassung Die Eich-Gleichung für das neue Korrekturverfahren wurde vom JIS-Modell (Japanese Industrial Standards) abgeleitet und ist über einen weiten Bereich von Zusammensetzungen durch Herstellung von lediglich binären Fe-Cr-Standards einsetzbar. Das beschriebene Verfahren bietet eine bessere Genauigkeit als die Methode nach dem Korrekturmodell von Rasberry-Heinrich. Sie betrug 0,08% für hochlegierte Stähle und 0,14% für Nickellegierungen.