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11.
Hydrolysis of penicillin G by combination of immobilized penicillin acylase and electrodialysis 总被引:1,自引:0,他引:1
Phenylacetic acid, as inhibitory product, was formed from a hydrolysis of penicillin G by immobilized penicillin acylase. In this article, electrodialysis was applied to remove phenylacetic acid continuously from the reaction mixture and to enhance an efficiency of the reaction. When 268 and 537 mM of penicillin G solution were used as the substrate, the concentration of phenylacetic acid in the reaction mixture could be maintained at less than 81 and 126 mM, respectively, and eventually, 86% and 88% of phenylacetic acid produced were removed from the reaction mixture at the end of the hydrolysis, respectively. Times required to reach 96% and 94.8% conversion from 268 and 537 mM of initial penicillin G could be reduced to 65% and 64% respectively, by means of electrodialysis; while 3.0% and 4.3% of initial penicillin G of 268 and 537 mM were permeated out of the reaction chamber during the hydrolysis, respectively. However, a loss of penicillin G by permeation could be reduced from 4.3% to 3.4% by a repeated addition of penicillin G. 相似文献
12.
Jonathan W. Yewdell 《Molecular & cellular proteomics : MCP》2022,21(7):100230
In the 35 years since the revelation that short peptides bound to major histocompatibility complex class I and II molecules are the secret of the major histocompatibility complex–restricted nature of T-cell recognition, there has been enormous progress in characterizing the immunopeptidome, the repertoire of peptide presented for immunosurveillance. Here, the major milestones in the journey are marked, the contribution of proteasome-mediated splicing to the immunopeptidome is discussed, and exciting recent findings relating the immunopeptidome to the translatome revealed by ribosome profiling (RiboSeq) is detailed. Finally, what is needed for continued progress is opined about, which includes the infusion of talented young scientists into the antigen-processing field, currently undergoing a renaissance; thanks in part to the astounding success of T-cell–based cancer immunotherapy. 相似文献
13.
Summary Ion: solute cotransporters frequency are incapable of achieving equilibrium between the solute accumulation and the transmembrane difference of the electrochemical potential of the ion. The presence of uncoupled flows of ion and solutes (leaks) is often advanced as an explanation. Here an alternative is discussed. The net accumulation of solute may be so slow that equilibrium can never be attained at finite times (e.g., several hours). Cotransporters may exhibit strong product inhibition, and the net influx of solute approaches zero far from equilibrium. The inherent slowness of net transport under these conditions is termed catalytic inefficiency. The likelihood that galactoside: H+ cotransport inEscherichia coli, hexose: H+ cotransport inChlorella vulgaris, andd-glucose: Na+ cotransport in brush-border membranes exhibit catalytic inefficiency is examined. The existence of strong product inhibition complicates the determination of the stoichiometry of cotransport and the characterization of chemically modified or mutant cotransporters. 相似文献
14.
Waste electrical and electronic equipment (WEEE) sheds light on the dimmer side of production and consumption patterns in modern societies. The rapid increase in its quantity and complexity contribute to the challenges it poses to solid waste management systems. Several members of the Organisation for Economic Co‐operation and Development (OECD) have relied on the principle of extended producer responsibility (EPR) to tackle the issue, with varying degrees of success. Several non‐OECD countries, including Thailand, are now developing WEEE programs and are looking for lessons from these first movers. This case study aims to provide an understanding both of this context and of the EPR program for WEEE proposed for Thailand. It finds that EPR mechanisms in general, and the proposed buy‐back system financed by product fees in Thailand in particular, have a strong potential to consolidate WEEE collection for the formal recycling sector by offering end users monetary incentives. On the negative side, this is an expensive combination of policy instruments, and the institutional design of the governmental fund is rigid. The policy proposal also contains no mechanism for product redesign—one of the objectives in the national WEEE strategy. This article suggests that the effectiveness of the policy might benefit from more flexibility at the compliance scheme level, in order to lessen the monopoly of the governmental fund, as well as the introduction of differentiated fees to promote environmentally friendly products. 相似文献
15.
Patterns and controls of the variability of radiation use efficiency and primary productivity across terrestrial ecosystems 总被引:2,自引:0,他引:2
Martín F. Garbulsky Josep Peñuelas Dario Papale Jonas Ardö Michael L. Goulden Gerard Kiely Andrew D. Richardson Eyal Rotenberg Elmar M. Veenendaal Iolanda Filella 《Global Ecology and Biogeography》2010,19(2):253-267
Aim The controls of gross radiation use efficiency (RUE), the ratio between gross primary productivity (GPP) and the radiation intercepted by terrestrial vegetation, and its spatial and temporal variation are not yet fully understood. Our objectives were to analyse and synthesize the spatial variability of GPP and the spatial and temporal variability of RUE and its climatic controls for a wide range of vegetation types. Location A global range of sites from tundra to rain forest. Methods We analysed a global dataset on photosynthetic uptake and climatic variables from 35 eddy covariance (EC) flux sites spanning between 100 and 2200 mm mean annual rainfall and between ?13 and 26°C mean annual temperature. RUE was calculated from the data provided by EC flux sites and remote sensing (MODIS). Results Rainfall and actual evapotranspiration (AET) positively influenced the spatial variation of annual GPP, whereas temperature only influenced the GPP of forests. Annual and maximum RUE were also positively controlled primarily by annual rainfall. The main control parameters of the growth season variation of gross RUE varied for each ecosystem type. Overall, the ratio between actual and potential evapotranspiration and a surrogate for the energy balance explained a greater proportion of the seasonal variation of RUE than the vapour pressure deficit (VPD), AET and precipitation. Temperature was important for determining the intra‐annual variability of the RUE at the coldest energy‐limited sites. Main conclusions Our analysis supports the idea that the annual functioning of vegetation that is adapted to its local environment is more constrained by water availability than by temperature. The spatial variability of annual and maximum RUE can be largely explained by annual precipitation, more than by vegetation type. The intra‐annual variation of RUE was mainly linked to the energy balance and water availability along the climatic gradient. Furthermore, we showed that intra‐annual variation of gross RUE is only weakly influenced by VPD and temperature, contrary to what is frequently assumed. Our results provide a better understanding of the spatial and temporal controls of the RUE and thus could lead to a better estimation of ecosystem carbon fixation and better modelling. 相似文献
16.
Charging up Battery Recycling Policies: Extended Producer Responsibility for Single‐Use Batteries in the European Union,Canada, and the United States 下载免费PDF全文
Extended producer responsibility (EPR) policies have proven effective at raising consumer awareness, expanding waste collection infrastructure, and shifting costs of end‐of‐life (EOL) management from municipalities to stewardship organizations. Yet, such policies have been less successful in advancing waste management programs that ensure a net environmental benefit. This article analyzes how EPR policies for single‐use batteries in the European Union (EU), Canada, and the United States address the environmental costs and benefits of EOL management. Considering these EPR policies is instructive, because single‐use batteries have high collection costs and are of relatively low economic value for waste processors. Without deliberate planning, the environmental burdens of collecting and recycling such batteries may exceed the benefits. This article considers how EPR policies for single‐use batteries integrate performance requirements such as collection rates, recycling efficiencies, and best available techniques. It argues that for such policies to be effective, they need to be extended to address waste collection practices, the life cycle consequences of EOL management, and the quality of recovered materials. Such strategies are relevant to EPR policies for other products with marginal secondary value, including some textiles, plastics, and other types of electronic waste. 相似文献
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《Saudi Journal of Biological Sciences》2022,29(2):816-821
All active natural molecules are not fully exploited as therapeutic agents, causing delays in the advancement of anticancer drug discovery. Viridiflorol is a natural volatile element that may work as anti-cancer compound. We tested the anticancer properties of viridiflorol at different concentrations ranging from 0.03 to 300 μM in vitro on three cancer cells including breast (MCF-7), lung (A549) and brain (Daoy). The cancer cells responses were documented after treatment using MTT and Annexin V assays. Viridiflorol showed cytotoxic effects against all tested cell lines, reducing cell viability in a concentration-dependent manner with variable IC50 values. Daoy and A549 cell lines were more sensitive to viridiflorol when compared with temozolomide and doxorubicin, respectively. Viridiflorol demonstrated the highest anticancer activity against the Daoy cells with an estimated IC50 of 0.1 µM followed by MCF-7 at 10 µM, and A549 at 30 µM. In addition, upon exposure to concentrations ranging from 30 µM to 300 µM of viridiflorol, early and late apoptotic cell death was induced in a concentration dependent manner in Daoy (55.8%-72.1%), MCF-7 (36.2%-72.7%) and A459 (35%-98.9%) cell lines, respectively. In conclusion, viridiflorol demonstrates cytotoxic and apoptotic ability in three different cancer cell lines (brain, breast and lung). 相似文献
20.
王佃亮 《中国生物工程杂志》2017,37(2):127-132
细胞药物具有自身特点和优势,对肿瘤、自身免疫性疾病等疑难病症具有较好疗效,起到了其他药物难以发挥的作用。但细胞药物在研发过程中,也存在伦理、安全等问题。针对这些问题,提出了一些解决策略,并介绍了细胞药物最新临床研发情况,对其广阔的发展前景进行了展望。 相似文献