Search results for "Serp"
showing 10 items of 205 documents
“Calcina e gesso e polvere di marmo”. Giacomo Serpotta e la plastica dello stucco tra Seicento e Settecento
2020
Il contributo prende in rassegna alcune delle principali opere prodotte dal maggiore stuccatore del Settecento siciliano, Giacomo Serpotta. Il percorso cronologico prende le mosse dalle esperienze della tradizione con gli apparati cinqucenteschi dei Ferraro e del padre Gaspare, proseguendo con le pietre miliari in cui la tecnica di Serpotta e la sua visione compositiva si evolvono. Sono affrontati anche alcuni aspetti tecnici costitutivi e costruttivi degli apparati.
Revising Ovid’s Metamorphoses: Dramatizing the Mythical in Mary Shelley’s Proserpine
2017
This contribution intends to assess the web of intertextual references in Mary Shelley’s drama Proserpine (1820), an early example of Romantic interest in revisionist mythology. The few critical efforts on the text focus on its transposition of the Ovidian narrative and its proto-feminist instances of mythical revisionism. Shelley’s adaptation primarily concerns characterization, structure and intended audience. In light of Ostriker’s (1984) suggestion that revisionist myth-making in women’s literary production constitutes a significant reshaping of shared culture and personal identity, Proserpine generally reads as a tale of defiance against patriarchal violence. The thoroughness of the ex…
Following the Phoenician example: western Mediterranean colonization by <em>Spirobranchus</em> cf. <em>tetraceros</em> (Annel…
2020
A newly established population of the fouling polychaete Spirobranchus cf. tetraceros is reported from the western Mediterranean (Valencia Port). Despite previous intensive surveys, this is the first record for the taxon in the Iberian Peninsula. Molecular analyses revealed that S. cf. tetraceros from Valencia are genetically identical to specimens from Heraklion, Crete, but different from those collected in the Red Sea and S. tetraceros sensu stricto from the type locality in Australia. Mediterranean and Red Sea S. cf. tetraceros form a well-supported monophyletic clade but are clearly distinct from New South Wales specimens of S. tetraceros. Our new molecular evidence supports the hypothe…
Crystallization and preliminary X-ray analysis of native and selenomethionyl vinorine synthase from Rauvolfia serpentina.
2005
Vinorine synthase (VS) is a central enzyme of the biosynthesis of the antiarrhythmic drug ajmaline and is a member of the BAHD superfamily of acyltransferases. So far, no three-dimensional structure with significant sequence homology with VS is known. Crystals of VS and selenomethionyl-labelled VS from the medicinal plant Rauvolfia serpentina have been obtained by the hanging-drop technique at 305 K with ammonium sulfate and PEG 400 as precipitants. VS crystals diffract to 2.8 Å and belong to space group P212121, with unit-cell parameters a = 82.3, b = 89.6, c = 136.2 Å. The selenomethionyl VS crystal was nearly isomorphous with the VS crystal.
Pigment epithelium-derived factor is a niche signal for neural stem cell renewal.
2006
Adult stem cells are characterized by self-renewal and multilineage differentiation, and these properties seem to be regulated by signals from adjacent differentiated cell types and by extracellular matrix molecules, which collectively define the stem cell "niche." Self-renewal is essential for the lifelong persistence of stem cells, but its regulation is poorly understood. In the mammalian brain, neurogenesis persists in two germinal areas, the subventricular zone (SVZ) and the hippocampus, where continuous postnatal neuronal production seems to be supported by neural stem cells (NSCs). Here we show that pigment epithelium-derived factor (PEDF) is secreted by components of the murine SVZ a…
Structure-based engineering of strictosidine synthase: auxiliary for alkaloid libraries.
2007
SummaryThe highly substrate-specific strictosidine synthase (EC 4.3.3.2) catalyzes the biological Pictet-Spengler condensation between tryptamine and secologanin, leading to the synthesis of about 2000 monoterpenoid indole alkaloids in higher plants. The crystal structure of Rauvolfia serpentina strictosidine synthase (STR1) in complex with strictosidine has been elucidated here, allowing the rational site-directed mutation of the active center of STR1 and resulting in modulation of its substrate acceptance. Here, we report on the rational redesign of STR1 by generation of a Val208Ala mutant, further describing the influence on substrate acceptance and the enzyme-catalyzed synthesis of 10-m…
Construction and expression of a dual vector for chemo-enzymatic synthesis of plant indole alkaloids inEscherichia coli
2010
A dual vector (pQE-70-STR1-SG) containing coding regions of strictosidine synthase (STR1, EC 4.3.3.2) and strictosidine glucosidase (SG, EC 3.2.1.105) from the Indian medicinal plant Rauvolfia serpentina was constructed. Functional expression of the vector in Escherichia coli cells (M15 strain) was proven by isolation of prepurified enzyme extracts, which show both STR1 and SG activities. Incubation of the enzyme in the presence of tryptamine and secologanin delivered the indole alkaloid cathenamine, demonstrating functional co-expression of both STR1- and SG-cDNAs. Cathenamine reduction by sodium borohydride leading to tetrahydroalstonine revealed the chemo-enzymatic indole alkaloid synthe…
Vomilenine Reductase — a novel Enzyme catalyzing a crucial Step in the Biosynthesis of the Therapeutically applied Antiarrhythmic Alkaloid Ajmaline
2002
Delineation of the biochemical pathway leading to the antiarrhythmic Rauvolfia alkaloid ajmaline has been an important target in biosynthetic research for many years. The biosynthetic sequence starting with tryptamine and the monoterpene secologanin consists of about 10 different steps. Most of the participating enzymes have been detected and characterized previously, except those catalyzing the reduction of the intermediate vomilenine. A novel NADPH-dependent enzyme that reduces the intermediate has been isolated from Rauvolfia serpentina cell suspension cultures. Vomilenine reductase (M(r )43 kDa, temp opt 30 degrees C, pH opt 5.7-6.2), saturates the indolenine double bond of vomilenine w…
3D-Structure and function of strictosidine synthase--the key enzyme of monoterpenoid indole alkaloid biosynthesis.
2008
Strictosidine synthase (STR; EC 4.3.3.2) plays a key role in the biosynthesis of monoterpenoid indole alkaloids by catalyzing the Pictet-Spengler reaction between tryptamine and secologanin, leading exclusively to 3alpha-(S)-strictosidine. The structure of the native enzyme from the Indian medicinal plant Rauvolfia serpentina represents the first example of a six-bladed four-stranded beta-propeller fold from the plant kingdom. Moreover, the architecture of the enzyme-substrate and enzyme-product complexes reveals deep insight into the active centre and mechanism of the synthase highlighting the importance of Glu309 as the catalytic residue. The present review describes the 3D-structure and …
L’apparizione della serpe ne La faula di Guillem de Torroella: folclore, politica e tecnica letteraria
2017
S ommario: Vissuto probabilmente fra il 1350 e il 1375, Guillem de Torroella e un nobile maiorchino coinvolto nel crollo del regno autonomo, reintegrato nella corona catalano-aragonese. Egli scrive un racconto in versi (1265, secondo l’unico manoscritto che contiene il testo per intero: 938 in lingua catalana e 327 in lingua francese). Si tratta de La faula , che narra un viaggio dell’autore sul dorso di una balena all’Isola Incantata. Qui Guillem incontra una serpe, che gli rivelera come li abbia trovato rifugio Artu dopo la battaglia di Salisbury. Per la serpe e possibile individuare fonti folcloriche locali (della zona di Girona) e le sue parole in francese sono un ulteriore indizio del …