323,041 research outputs found
Transglutaminases: future perspectives
No full textThis is the third special issue focused on "Transglutaminases" that is now available on this journal and dedicated to one of the pioneers of these enzymes, John Edward Folk, who died December 2010 [see in this issue Beninati et al. 2012a]. The first edition, "Polyamines and Transglutaminases" was published in Amino Acids, vol 26, no. 4, 2004, with the contribution of two prestigious Guest Editors as Alberto Abbruzzese and Mauro Piacentini. This editorial initiative was followed by the second special issue published in occasion of the 50th years of the discovery of transglutaminase. Indeed, "Transglutaminase 2: 50th Anniversary of the Discovery" Amino Acids, vol 36, no. 4, 2009, was published with the valuable collaboration of Carlo Maria Bergamini and Mauro Piacentini (Beninati et al. 2009). To continue with this editorial tradition, on this occasion, an outstanding board of Guest Editors composed by Francesco Facchiano and Mauro Piacentini has also been invited to promote this initiative and recruit a selected panel of Authors, many of who participated in the first and second edition of the Gordon Conference on Transglutaminases: "Transglutaminases in Human Diseases Processes" chaired by Rickard L Eckert and Kapil Mehta on July 18-23, 2010, and by Kapil Mehta and Mauro Piacentini on July 15-20, 2012, held at Davidson College, NC, USA. In this Amino Acids special issue, the manuscripts were selected to reflect the progress and the future perspectives of transglutaminases
Transglutaminase 2, a double face enzyme
No full textDuring the years Amino Acids have dedicated much attention to the transglutaminase (Tgase) field and this special issue is therefore the fifth of a series. In a previous occasion, we celebrated the 50 years from transglutaminase discovery with the editorial “An overview of the first 50 years of transglutaminase research” (Beninati et al. 2009). Following ideally from that point, we have now chosen as general theme for this issue the multiple roles played by type 2 transglutaminase as a multi-face protein.
Most people are accustomed to analyze events and facts by taking into account objects and their opposite to get the whole, as in the case of light and darkness, day and night, or black and white as within a chessboard. This is also the case for type 2 transglutaminase (Tgase2): to get the complete picture we must examine both sides of the problem, the protein with its opposite activities, the involvement in cells and tissues leading either to cell growth/differentiation or conversely to cell death/atrophy, and their implications in health protection and pathology. The aim in launching this special issue was to contribute to settle these topics and we introduce now these general concepts dividing ideally the path in the steps mentioned above
γ-Tocopherol inhibits human prostate cancer cell proliferation by up-regulation of transglutaminase 2 and down-regulation of cyclins
No full textTo establish a system to study differentiation therapy drugs, we used the androgen-independent human prostate PC-3 tumor cell line as a target and α- and γ-tocopherol as inducers. Effects of α- and γ-tocopherol on the cell cycle, proliferation and differentiation, were examined. A more significant growth inhibition activity for γ- than for α-tocopherol was observed. Flow cytometry analysis of α- and γ-tocopherol-treated prostate carcinoma PC3 cells showed decreased progression into the S-phase. This effect, particularly evident for γ-tocopherol, was associated with an up-regulation and increased activity of transglutaminase 2 (TG2), a reduced DNA synthesis and a remarkable decreased levels of cyclin D1 and cyclin E. Activation of TG2 suggests that γ-tocopherol has an evident differentiative capacity on PC3 cells, leading to an increased expression of TG2, and reduced cyclin D1 and cyclin E levels, affecting cell cycle progression. It is feasible that up-regulation and activation of TG2, associated with a reduced proliferation, are parts of a large-scale reprogramming that can attenuate the malignant phenotype of PC3 cells in vitro. These data suggest further investigation on the potential use of this γ-form of vitamin E as a differentiative agent, in combination with the common cytotoxic treatments for prostate cancer therapy
MW assisted synthesis of LiFePO4 for high power applications
No full textLiFePO4/C was prepared by solid-state reaction from Li3PO4, Fe3(PO4)2.8H2O, carbon and glucose in a few minutes in a scientific MW oven with temperature and power control. The material was characterized by X-ray diffraction, scanning electron microscopy and by TGA analysis to evaluate carbon content. The electrochemical characterization as positive electrode in EC- DMC 1 M LiPF6 was performed by galvanostatic charge–discharge cycles at C/10 to evaluate specific capacity and by sequences of 10 s discharge-charge pulses, at different high C-rates (5-45 C) to evaluate pulse-specific power in simulate operative conditions for full-HEV application. The maximum pulse-specific power and, particularly, pulse efficiency values are quite high and make MW synthesis a very promising route for mass production of LiFePO4/C for full-HEV batteries at low energy costs
The role of carbon paper as current collector-substrate in tin-based anodes for lithium-ion batteries
No full textThe strategies of the intermetallic compounds and of morphological conversion toward nanomaterials to buffer the volume changes during the lithiation/delithiation processes in lithium-metal alloys, although beneficial, have been not conclusive to overcome this drawback.
To improve the cyclability performance of nanometric lithium-metal alloys we regarded the electrode materials as a whole with the current collector and we focused our efforts on the carbon paper (CP) as an alternative substrate-current collector to the conventional copper. The CP, with its three-dimensional interconnected conductive fibers, was able to host the metals and intermetallic materials and to guarantee a good electric contact without addition of carbon as conducting agent, providing a significantly improved cycling stability of these electrodes as shown in Figure 1.
To get an insight into the effective role of CP on the cycling stability of lithium-metal alloy/CP electrodes we compared the electrochemical and structural behavior over repeated lithiation/delithiation cycles of different types of tin-based materials on CP such as Sn, Cu6Sn5 and Sn2Mn and the results of this study are presented and discussed in this contribution
Fast sol-gel synthesis of LiFePO4/C for high power lithium-ion batteries for hybrid electric vehicle application
No full textLiFePO4/C of high purity grade was successfully synthesized by microwave accelerated sol-gel
synthesis and showed excellent electrochemical performance in terms of specific capacity and
stability. This cathode material was characterized in battery configuration with a graphite counter
electrode by USABC-DOE tests for Power-Assist Hybrid Electric Vehicle. It yielded a nonconventional
Ragone plot that represents complexity of battery functioning in power-assist HEV
and shows that the pulse power capability and available energy of such a battery surpasses the DOE
goal for such an application
Cyclability of tin and tin-based intermetallic compounds on carbon paper current collector-substrate
No full textAlthough lithium-ion battery technology is well consolidated, research efforts have been greatly active in attempts to ameliorate the performance of these batteries. In particular, the research on negative electrodes has been not only focused on the optimization of carbonaceous materials but also on alternative materials, such as lithium-metal alloys, which are very attractive for their specific capacity. However, their high volume changes during the lithiation/delithiation processes cause materials pulverization and, consequently, loss of electrical contact among particles, determining poor cycle life. The strategies of the intermetallic compounds and of morphological conversion toward nanomaterials to buffer the volume changes, although beneficial, have been not conclusive to overcome this drawback.
To improve the cyclability performance of nanometric lithium-metal alloys we regarded the electrode materials as a whole with the current collector and we focused our efforts on the carbon paper (CP) as an alternative substrate-current collector to the conventional copper. The CP, with its three-dimensional interconnected conductive fibers, was able to host the metals and intermetallic materials and to guarantee a good electric contact without addition of carbon as conducting agent, providing a significantly improved cycling stability of these electrodes.
To get an insight into the effective role of CP on the cycling stability of lithium-metal alloy/CP electrodes we compared the electrochemical and structural behavior over repeated lithiation/delithiation cycles of different types of tin-based materials on CP such as Sn, Cu6Sn5 and Sn2Mn and the results of this study are presented and discussed in this contribution
Il ruolo del carbon paper come substrato-collettore di corrente in anodi a base di stagno per batterie litio-ione
No full textLe strategie dei composti intermetallici e della conversione morfologica verso i nanomateriali per contrastare le variazioni di volume durante i processi di litiazione/delitiazione delle leghe litio-metallo, sebbene abbiano apportato notevoli benefici, non hanno ancora risolto questo problema che costituisce una forte limitazione all’impiego di tali materiali nelle batterie litio-ione.
Per migliorare le prestazioni in termini di vita di ciclo delle leghe nanometriche litio-metallo abbiamo considerato il materiale elettrodico come un tutto con il suo collettore di corrente ed abbiamo focalizzato la nostra attenzione sul carbon paper (CP) proponendolo come substrato-collettore alternativo al rame comunemente usato. Il CP, con la sua matrice tridimensionale di fibre conduttrici interconnesse, si è dimostrato in grado di ospitare Sn e composti intermetallici a base di Sn e di garantire un buon contatto elettrico senza l’aggiunta di carbone come additivo conduttore, fornendo una stabilità a ripetuti cicli di carica/scarica significativamente più elevata di quella ottenuta con i collettori di rame.
Per chiarire l’effettivo ruolo del CP sulla stabilità a ripetuti cicli di litiazione/delitiazione di elettrodi a base di Sn su tali collettori abbiamo confrontato il comportamento elettrochimico e strutturale durante ripetuti cicli di diversi tipi di elettrodo quali Sn/CP, Cu6Sn5/CP e Sn2Mn/CP e i risultati di questo studio sono presentati e discussi nel presente contributo
Phytochemicals and protein-polyamine conjugates by transglutaminase as chemopreventive and chemotherapeutic tools in cancer.
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