61 research outputs found
Old drawback on azlactone formation revealed by a combination of theoretical and experimental studies
New insights into the formation of azlactone heterocycles bearing different substituents are hereby presented. The sum of both kinetic and thermodynamic factors contributes for the formation of 2-alkyl or 2-aryl substituted azlactones, while the cyclization of 2-alcoxy azlactones is less favored. These results are in perfect accordance with experimental observations obtained by infrared (IR) and electrospray ionization mass spectrometry (ESI(+)-MS) of the crude reaction mixture.
Structure and electronic properties of alkylthiophenes coupled by Head-to-Tail and Head-to-Head regioselectivity
Reactivity of 5a,6-anhydrotetracycline platinum(II) complex with biological nucleophiles: a theoretical study
This paper describes a theoretical analysis of the interaction between 5a,6-anhydrotetracycline platinum(II) complex (AHTC-Pt) and some biological nucleophiles; adenine (A), guanine (G), cysteine (Cys) and methionine (Met). The aquated species [Pt(AHTC)Cl(H2O)]+ was taken as reagent for the processes studied here. For DNA bases (A and G), the calculated values for ΔGa,aq at the B3LYP/6-311+G(2d,p) level were 21.7 and 20.7 kcal mol-1 for interaction with A and G, respectively, which are in accordance with the expected behavior of faster process involving G. These values are higher than the experimental activation energy for the parent compound cisplatin (18.5 kcal mol-1 for interaction with G). For the process involving the amino-acids, the barriers were 17.6 (Cys) and 18.5 kcal mol-1 (Met), which are lower than the observed values for cisplatin (20.5 and 20.2 kcal mol-1, respectively). These outcomes show that AHTC-Pt hybrid complex may be considered a promising lead compound in the development of novel anticancer drugs based on platinum complex
Lactose hydrolysis potential and thermal stability of commercial ÎČ-galactosidase in UHT and skimmed milk
A voz dos bandos: colectivos de justiça e ritos da palavra portuguesa em Timor Leste colonial
Este artigo examina as relaçÔes entre o discurso da justiça e a prĂĄtica do ritual nos bandos do governo colonial portuguĂȘs em Timor Leste, entre a segunda metade do sĂ©culo XIX e as primeiras dĂ©cadas do sĂ©culo XX. Os bandos consistiam em ordens e instruçÔes de comando emanadas pelo governador portuguĂȘs em DĂli, e comunicadas de forma cerimonial por oficiais Ă s populaçÔes dos diversos reinos timorenses dispersos pelo paĂs. Bandos eram um instrumento por excelĂȘncia de governação colonial dos assuntos indĂgenas, servindo para arbitrar conflitos, punir transgressĂ”es e, em geral, instituir realidades no mundo timorense. Contudo, esta instituição assumiu igualmente uma singular expressĂŁo nos usos timorenses, servindo bandos para comunicar tambĂ©m as ordens de autoridades tradicionais, os liurais. O artigo acompanha as variaçÔes coloniais e indĂgenas que os bandos adquiriram em Timor Leste, conceptualizando-os enquanto colectivos de justiça. Ao considerar assim os bandos como colectivos â formaçÔes heterogĂ©neas em que elementos linguĂsticos e nĂŁo linguĂsticos se combinam na produção de efeitos de poder sobre as populaçÔes â o artigo propĂ”e uma via conceptual alternativa Ă s perspectivas linguĂsticas e literĂĄrias de anĂĄlise do discurso colonial
Fenologics characteristics of the âSicilianoâ lemon tree on two rootstocks influenced by liming and boron addition
OvĂĄrio-histerectomia vĂdeo-assistida com Ășnico portal em cadelas: estudo retrospectivo de 20 casos
Adaptabilidade e estabilidade de cultivares de milho no Nordeste brasileiro no triĂȘnio 1998 a 2000
The complete genome sequence of Chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability
Chromobacterium violaceum is one of millions of species of free-living microorganisms that populate the soil and water in the extant areas of tropical biodiversity around the world. Its complete genome sequence reveals (i) extensive alternative pathways for energy generation, (ii) â500 ORFs for transport-related proteins, (iii) complex and extensive systems for stress adaptation and motility, and (iv) wide-spread utilization of quorum sensing for control of inducible systems, all of which underpin the versatility and adaptability of the organism. The genome also contains extensive but incomplete arrays of ORFs coding for proteins associated with mammalian pathogenicity, possibly involved in the occasional but often fatal cases of human C. violaceum infection. There is, in addition, a series of previously unknown but important enzymes and secondary metabolites including paraquat-inducible proteins, drug and heavy-metal-resistance proteins, multiple chitinases, and proteins for the detoxification of xenobiotics that may have biotechnological applications
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