A techno-economic assessment of the generation and usage of biogenic gases in Chile as a substitute of natural gas

The study uses a novel techno-economic approach to calculate the economic potential of biomass in Chile. The pathway of electricity generation and that of upgraded biogas were assessed and compared. Both routes were evaluated employing proven technologies. Through a mathematical procedure relying on limits of potential, supply-cost curves were constructed. The results, technical potential, were integrated into a geographical information system (GIS) to show the energy distribution nationwide

Challenges for Sustainable Biomass Utilisation : Proceedings of the Chilean-German Biociclo Workshop (Karlsruhe, 26.03.2009)

The energetic use of biomass can provide solutions for the growing worldwide demand for energy and fuel. This book contains the contributions for the final workshop of the "Biociclo" research exchange between the Universidad de Concepción and the Universität Karlsruhe. It reflects interdisciplinarity of the workshop\u27s participants with contributed papers about Biomass Utilization Paths in Chile, Pyrolysis and Life-Cycle Assessment of Biomass and Logistic Concepts of Biomass Utilization Concepts

L'industrie lithique épigravettienne de Saint-Antoine - Locus 2 (Vitrolles, Hautes-Alpes) : première analyse

International audienc

Family 1 Glycosyltransferase UGT706F8 from Zea mays Selectively Catalyzes the Synthesis of Silibinin 7-O-β-d -Glucoside

Regioselective glycosylation is a chemical challenge, leading to multistep syntheses with protecting group manipulations, ultimately resulting in poor atom economy and compromised sustainability. Enzymes allow eco-friendly and regioselective bond formation with fully deprotected substrates in a single reaction. For the selective glucosylation of silibinin, a pharmaceutical challenged with low solubility, enzyme engineering has previously been employed, but the resulting yields and k$_{cat}$ were limited, prohibiting the application of the engineered catalyst. Here, we identified a naturally regioselective silibinin glucosyltransferase, UGT706F8, a family 1 glycosyltransferase from Zea mays. It selectively and efficiently (k$_{cat}$ = 2.1 ± 0.1 s$^{–1}$; KM = 36.9 ± 5.2 $μ$M; TTN = 768 ± 22) catalyzes the quantitative synthesis of silibinin 7-O-β-d-glucoside. We solved the crystal structure of UGT706F8 and investigated the molecular determinants of regioselective silibinin glucosylation. UGT706F8 was the only regioselective enzyme among 18 glycosyltransferases found to be active on silibinin. We found the temperature optimum of UGT706F8 to be 34 °C and the pH optimum to be 7–8. Our results indicate that UGT706F8 is an efficient silibinin glycosyltransferase that enables biocatalytic production of silbinin 7-O-β-d-glucoside

Family 1 Glycosyltransferase UGT706F8 from <i>Zea mays</i> Selectively Catalyzes the Synthesis of Silibinin 7-<i>Ο</i>-<i>β</i>-D-Glucoside

Regioselective glycosylation is a chemical challenge, leading to multistep syntheses with protecting group manipulations, ultimately resulting in poor atom economy and compromised sustainability. Enzymes allow eco-friendly and regioselective bond formation with fully deprotected substrates in a single reaction. For the selective glucosylation of silibinin, a pharmaceutical challenged with low solubility, enzyme engineering has previously been employed, but the resulting yields and k$_{cat}$ were limited, prohibiting the application of the engineered catalyst. Here, we identified a naturally regioselective silibinin glucosyltransferase, UGT706F8, a family 1 glycosyltransferase from Zea mays. It selectively and efficiently (k$_{cat}$ = 2.1 ± 0.1 s$^{–1}$; KM = 36.9 ± 5.2 $μ$M; TTN = 768 ± 22) catalyzes the quantitative synthesis of silibinin 7-O-β-d-glucoside. We solved the crystal structure of UGT706F8 and investigated the molecular determinants of regioselective silibinin glucosylation. UGT706F8 was the only regioselective enzyme among 18 glycosyltransferases found to be active on silibinin. We found the temperature optimum of UGT706F8 to be 34 °C and the pH optimum to be 7–8. Our results indicate that UGT706F8 is an efficient silibinin glycosyltransferase that enables biocatalytic production of silbinin 7-O-β-d-glucoside

GASP: A pan-specific predictor of family 1 glycosyltransferase specificity enabled by a pipeline for substrate feature generation and large-scale experimental screening

Glycosylation represents a major chemical challenge; while it is one of the most common reactions in Nature, conventional chemistry struggles with stereochemistry, regioselectivity and solubility issues. In contrast, family 1 glycosyltransferase (GT1) enzymes can glycosylate virtually any given nucleophilic group with perfect control over stereochemistry and regioselectivity. However, the appropriate catalyst for a given reaction needs to be identified among the tens of thousands of available sequences. Here, we present the Glycosyltransferase Acceptor Specificity Predictor (GASP) model, a data-driven approach to the identification of reactive GT1:acceptor pairs. We trained a random forest-based acceptor predictor on literature data and validated it on independent in-house generated data on 1001 GT1:acceptor pairs, obtaining an AUROC of 0.79 and a balanced accuracy of 72%. GASP is capable of parsing all known GT1 sequences, as well as all chemicals, the latter through a pipeline for the generation of 153 chemical features for a given molecule taking the CID or SMILES as input (freely available at https://github.com/degnbol/GASP). GASP had an 83% hit rate in a comparative case study for the glycosylation of the anti-helminth drug niclosamide, significantly outperforming a hit rate of 53% from a random selection assay. However, it was unable to compete with a hit rate of 83% for the glycosylation of the plant defensive compound DIBOA using expert-selected enzymes, with GASP achieving a hit rate of 50%. The hierarchal importance of the generated chemical features was investigated by negative feature selection, revealing properties related to cyclization and atom hybridization status to be the most important characteristics for accurate prediction. Our study provides a ready-to-use GT1:acceptor predictor which in addition can be trained on other datasets enabled by the automated feature generation pipelines

L’horizon anthropologique des transferts culturels

Les imbrications entre les aires culturelles européennes, en particulier entre la France et l'Allemagne, peuvent s'analyser à la lumière des modèles développés par les anthropologues sur des terrains aussi éloignés que l'Australie, l'Inde, l'Afrique, la Chine ou l'Amérique du Sud. Mais la genèse des modèles anthropologiques a elle-même une histoire allemande, franco-allemande. Dans ces deux dimensions, l'anthropologie a partie liée avec la question des transferts culturels. Cherchant à mieux reconnaître la place de cette question dans la science de l'homme en société, les contributions du présent volume explorent, de Guillaume de Humboldt, Alexandre de Humboldt ou Herder à Karl Lamprecht en passant par Krause, Bastian, Max Müller, Frobenius, Franz Boas, quelques jalons d'une pensée de l'altérité et surtout des rencontres entre cultures. Elles essaient de clarifier les concepts, métissage, hybridation, traduction, qui servent à penser ces rencontres. Elles remettent en cause l'approche empirique d'une histoire croisée des influences, corrigent les avatars essentialistes de l'histoire sociale comparée. Elles démontent les analyses historiques qui, pour étudier les métissages, présupposent naïvement l'existence première de systèmes homogènes. L'histoire des modèles anthropologiques de rencontres entre cultures révèle que la question des transferts culturels, bien qu'elle plonge ses racines dans l'histoire franco-allemande, peut s'élargir à des espaces qui n'ont plus rien à voir avec ses cloisonnements