131,063 research outputs found
SPECIFIC RECOGNITION OF N-ACETYLNEURAMINIC ACID IN THE G(M2) EPITOPE BY HUMAN G(M2) ACTIVATOR PROTEIN
No full textG(M2) Activator is a low molecular weight protein cofactor that stimulates the enzymatic conversion of G(M2) into G(M3) by human beta-hexosaminidase A and also the conversion of G(M2) into G(A2) by clostridial sialidase (Wu, Y.-Y., Lockyer, J. M., Sugiyama, E., Pavlova, N. V., Li, Y.-T., and Li, S.- C. (1994) J. Biol. Chem. 269, 16276-16283). Among the five known activator proteins for the enzymatic hydrolysis of glycosphingolipids, only G(M2) activator is effective in stimulating the hydrolysis of G(M2). However, the mechanism of action of G(M2) activator is still not well understood, Using a unique disialosylganglioside, GalNAc-G(D1a), as the substrate, we were able to show that in the presence of G(M2) activator, GalNAc-G(D1a) was specifically converted into GalNAc-G(M1a) by clostridial sialidase, while in the presence of saposin B, a nonspecific activator protein, GalNAc-G(D1a) was converted into both GalNAc-G(M1a) and GalNAc-G(M1b). individual products generated from GalNAc-G(D1a) by clostridial sialidase were identified by thin layer chromatography, negative secondary ion mass spectrometry, and immunostaining with a monoclonal IgM that recognizes the G(M2) epitope. Our results clearly show that G(M2) activator recognizes the G(M2) epitope in GalNAc-G(D1a). Thus, G(M2) activator may interact with the trisaccharide structure of the G(M2) epitope and render the GalNAc and NeuAc residues accessible to beta-hexosaminidase A and sialidase, respectively
Characterization of an alternatively spliced G(M2) activator protein, G(M2A) protein - An activator protein which stimulates the enzymatic hydrolysis of N-acetylneuraminic acid, but not N-acetylgalactosamine, from G(M2)
No full textG(M2) activator protein is a protein cofactor which stimulates the enzymatic hydrolysis of both GalNAc and NeuAc from G(M2). We have previously isolated two cDNA clones, G(M2) activator cDNA and G(M2A) cDNA, for human G(M2) activator protein (Nagarajan, S., Chen, H.-C., Li, S.-C., Li, Y.-T., and Lockyer, J. M. (1992) Biochem. J. 282, 807-813). G(M2A) mRNA is an RNA alternative splicing product that contains exons 1, 2, 3, and intron 3 of the genomic DNA sequence of G(M2) activator protein (Klima, H., Tanaka, A., Schnabel, D., Nakano, T., Schroder, M., Suzuki, K., and Sandhoff, K. (1991) FEES Left. 289, 260-264). G(M2A) cDNA encodes a protein (G(M2A) protein) containing 1-109 of the 160 amino acids of human G(M2) activator protein, plus a tripeptide (VST) encoded by intron 3 at the COOH terminus. Thus, G(M2A) protein can be regarded as a form (truncated version) of G(M2) activator protein. We have expressed G(M2A) cDNA in Escherichia coli using pT7-7 as the vector. The recombinant G(M2A) protein was purified to an electrophoretically homogeneous form and was found to stimulate the hydrolysis of NeuAc from G(M2) by clostridial sialidase, but not the hydrolysis of GalNAc from G(M2) by beta-hexosaminidase A. Like G(M2) activator protein, G(M2A) protein also specifically recognized the terminal G(M2) epitope in GalNAc-GD1a and stimulated the hydrolysis of only the external NeuAc from this ganglioside by clostridial sialidase. These results enabled us to discern the enzymatic hydrolyses of GalNAc and NeuAc from the G(M2) epitope and established that the NeuAc recognition domain of G(M2) activator protein is located within amino acids 1-109. The presence of G(M2A) mRNA in human tissues and the selective stimulation of NeuAc hydrolysis by G(M2A) protein indicate that this activator protein may be involved in the catabolism of G(M2) through the asialo-G(M2) pathway
Representative Bureaucracy and the Willingness to Coproduce: An Experimental Study
No full textRelying on the theory of representative bureaucracy—specifically, the notion of symbolic representation—this article examines whether varying the number of female public officials overseeing a local recycling program influences citizens’ (especially women's) willingness to cooperate with the government by recycling, thus coproducing important policy outcomes. Using a survey experiment in which the first names of public officials are manipulated, the authors find a clear pattern of increasing willingness on the part of women to coproduce when female names are more represented in the agency responsible for recycling, particularly with respect to the more difficult task of composting food waste. Overall, men in the experiment were less willing to coproduce across all measures and less responsive to the gender balance of names. These findings have important implications for the theory of representative bureaucracy and for efforts to promote the coproduction of public services.This is the peer reviewed version of the following article: Riccucci, Norma M., Van Ryzin, Gregg G. & Li, Huafang. (2015). Representative Bureaucracy and the Willingness to Coproduce: An Experimental Study. Public Administration Review, which has been published in final form at http://dx.doi.org/10.1111/puar.12401. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Peer reviewe
G-twisted Braces and Orbifold Landau–Ginzburg Models
No full text© 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Given an algebra with a group G-action, we construct brace structures for its G-twisted Hochschild cochains. An an application, we construct G-Frobenius algebras for orbifold Landau–Ginzburg B-models and present explicit orbifold cup product formula for all invertible polynomials11Nsciescopu
Structural and electrochemical characterization of xLi[Li1/3Mn2/3]O2·(1 - x)Li[Ni1/3Mn1/3Co1/3]O2 (0 ≤ x ≤ 0.9) as cathode materials for lithium ion batteries
No full textA series of cathode materials with molecular notation of xLi[Li1/3Mn2/3]O2·(1 - x)Li[Ni1/3Mn1/3Co1/3]O2 (0 ≤ x ≤ 0.9) were synthesized by combination of co-precipitation and solid state calcination method. The prepared materials were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques, and their electrochemical performances were investigated. The results showed that sample 0.6Li[Li1/3Mn2/3]O2·0.4Li[Ni1/3Mn1/3Co1/3]O2 (x = 0.6) delivers the highest capacity and shows good capacity-retention, which delivers a capacity ∼250 mAh g-1 between 2.0 and 4.8 V at 18 mA g-1. © 2008 Elsevier B.V. All rights reserved
Letter by Ristagno and Li Regarding Article, "Waveform Analysis-Guided Treatment Versus a Standard Shock-First Protocol for the Treatment of Out-of-Hospital Cardiac Arrest Presenting in Ventricular Fibrillation: Results of an International Randomized, Controlled Trial"
No full textTiF<sub>3</sub> catalyzed MgH<sub>2</sub> as a Li/Na ion battery anode
No full textMgH2 has been considered as a potential anode material for Li ion batteries due to its low cost and high theoretical capacity. However, it suffers from low electronic conductivity and slow kinetics for hydrogen sorption at room temperature that results in poor reversibility, cycling stability and rate capability for Li ion storage. This work presents a MgH2–TiF3@CNT based Li ion battery anode manufactured via a conventional slurry based method. Working with a liquid electrolyte at room temperature, it achieves a high capacity retention of 543 mAh g−1 in 70 cycles at 0.2 C and an improved rate capability, thanks to the improved hydrogen sorption kinetics with the presence of catalytic TiF3. Meanwhile, the first realization of Na ion uptake in MgH2 has been evidenced in experiments.Accepted Author ManuscriptChemE/Materials for Energy Conversion and Storag
A finite-element algorithm for electromagnetic induction in two-dimensional anisotropic conductivity structures
No full textElectromagnetic fields are computed for a 2-D electrically anisotropic earth using a finite-element technique. The models consist of a background layered structure, containing anisotropic blocks. Each block and layer may be anisotropic by assigning to them 3x3 conductivity tensors. The forward modelling problem leads to a coupled system of two partial differential equations for the strike-parallel field components E-x and H-x. They are solved numerically using the finite-element (FE) method. The resulting system of linear FE equations is solved using a preconditioned conjugate gradient method. Subsequently, strike-perpendicular field components E-y and H-y at the surface are found by numerical differentiation of E-x and H-x, using spline interpolation. The 2-D FE algorithm has been validated by comparison with a 2-D finite-difference solution. Three model types are used to demonstrate the effect of anisotropy upon the magnetotelluric responses: horizontal, vertical and dipping anisotropy. A fourth model simulates the effect of anisotropy in the context of shear and subduction zones. The model responses simulate the splitting of apparent resistivity curves at long periods, as well as the existence of tensor impedances with significant diagonal elements, as has been observed previously
CHARACTERIZATION OF A NONSPECIFIC ACTIVATOR PROTEIN FOR THE ENZYMATIC-HYDROLYSIS OF GLYCOLIPIDS
No full textWe have studied the substrate specificities of a non-specific activator protein on the enzymatic hydrolyses of the following compounds: G(M1) and G(M2), as well as several of their derivatives including oligosaccharides, GgOse3Cer-II3-sulfate and LacCer-II3-sulfate, Gb-Ose3Cer and GgOse4Cer, three neolacto-series glycosphingolipids, and two non-ceramide glycolipids. Our results show that this activator protein has a broad spectrum of activity and exhibits the properties of a nonspecific natural detergent. The evidence of non-specificity was the ability of this activator protein to stimulate the hydrolyses of glycolipids, regardless of glycosphingolipids or non-ceramide glycolipids, carried out by glycosidases from animals, plants, and microorganisms. Its activity was, however, limited to substrates that had a lipid moiety. The oligosaccharide of G(M1) and deacetyl-fatty acid free G(M1) (II3-NeuGg-Ose4-sphingosine) were hydrolyzed by β-galactosidase in the absence of this activator protein
The generalized Liénard polynomial differential systems x'=y,y'= -g(x) - f (x)y with deg g = deg f 1 are not Liouvillian integrable
No full textAgraïments: The second author was supported by Portuguese National Funds through FCT - Fundação para a Ciência e a Tecnologia within the project PTDC/MAT/117106/2010 and by CAMGSD (PEst-OE/EEI/LA0009/2013)We prove the nonexistence of Liouvillian first integrals for the generalized Li\'enard polynomial differential systems of the form x' = y, y'=-g(x)-f(x)y, where g(x) and f(x) are arbitrary polynomials such that g = f 1
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