Search results for "substrate"
showing 10 items of 1018 documents
Theoretical insights in enzyme catalysis
2004
In this tutorial review we show how the methods and techniques of computational chemistry have been applied to the understanding of the physical basis of the rate enhancement of chemical reactions by enzymes. This is to answer the question: Why is the activation free energy in enzyme catalysed reactions smaller than the activation free energy observed in solution? Two important points of view are presented: Transition State (TS) theories and Michaelis Complex (MC) theories. After reviewing some of the most popular computational methods employed, we analyse two particular enzymatic reactions: the conversion of chorismate to prephenate catalysed by Bacillus subtilis chorismate mutase, and a m…
Studies on erythrocyte acetylcholinesterase in essential hypertension.
1982
There is accumulating evidence that acetylcholinesterase (AChE might be involved in the transport of sodium across biological membranes. Consequently, because in primary hypertension abnormalities in the transport of sodium by red blood cells have been documented. AChE activities were measured in hemoglobin-free red-blood-cell membranes of patients with essential hypertension. In the absence of any effectors, the Michaelis constant of AChE for acetylcholine (Km) was 1.57 . 10(-5) mol/l, both in normotensives and in hypertensives. Sodium inhibited AChE at low substrate concentrations, whereas the enzyme was activated by sodium at moderate and high substrate levels. With increasing sodium, th…
Compost di qualità per la coltivazione del peperoncino ornamentale in vaso
2010
In two years (2008 and 2009), the research centre Co.Ri.SSIA evalueted the suitability of compost obtained from organic municipal waste used a growth substrate for three varieties of ornamental chili pepper (Capsicum annuum). Research was carried out at the Orleans Experimental Farm at the University of Palermo. In addition to the control standard substrate (a 70:30 mix by volume of peat and perlite), three substrates were tested, formed by varying percentage mixes of compost, peat and perlite. During the initial cultivation stage, chemical and physical analyses were carried out on the different substrates. Subsequently, morphometric data were collected in order to evaluate the plant orname…
Reactions of Piperazin-2-one, Morpholin-3-one, and Thiomorpholin-3-one with Triethyl Phosphite Prompted by Phosphoryl Chloride: Scope and Limitations
2019
The reaction of the title lactams with triethyl phosphite prompted by phosphoryl chloride provided six-membered ring heterocyclic phosphonates or bisphosphonates. These novel scaffolds might be of interest as building blocks in medicinal chemistry. The course of the reaction was dependent on the structure of the used substrate. Thus, morpholin-3-one and thiomorpholin-3-one readily provided the corresponding 1,1-bisphosphonates (compounds 1, 2, 7, 14 and 16), whereas the protection of their nitrogen atom resulted in the formation of dehydrophosphonates (compounds 5, 6, and 8). Piperazin-2-one reacted differently yielding mixture of cis- and trans- piperazine-2,3-diyl-bisphosphonates (compoun…
Zirconocene complexes bearing novel 3-dimethylamino-1,2-dihydropentalene derived ligand systems.
2010
Coupling of the N,N-dimethylacrylamides 6a-c with cyclopentadienide resulted in the formation of the substituted 3-dimethylamino-1,2-dihydropentalnenes 2a-c. Deprotonation followed by metallation with CpZrCl(3)·DME gave the substituted zirconocenes 12a-c. The reaction of 3-dimethylamino-1-methyl-dihydropentalene 2a with ZrCl(2)(NMe(2))(2)·2THF resulted in a unique coupling between a pair of the aminodihydropentalene derivatives to yield an unsymmetrically bridged novel ansa-zirconocene framework (9a). Treatment of the 1,1-dimethyl-substituted substrate 2b with this Zr-amido reagent in contrast resulted in a clean deprotonation and formation of the unbridged bis(dimethylaminohydropentalenyl)…
Domain structure of epitaxial SrRuO3 thin films
2005
Growth of multidomains in epitaxial thin-film oxides is known to have a detrimental effect on some functional properties, and, thus, efforts are done to suppress them. It is commonly accepted that optimal properties of the metallic and ferromagnetic $\mathrm{SrRu}{\mathrm{O}}_{3}$ (SRO) epitaxies can only be obtained if vicinal $\mathrm{SrTi}{\mathrm{O}}_{3}$ (001) (STO) substrates are used. It is believed that this results from the suppression of multidomain structure in the SRO film. Here we revise this important issue. Nanometric films of SRO have been grown on STO(001) vicinal substrates with miscut $({\ensuremath{\theta}}_{V})$ angles in the $\ensuremath{\sim}0.04\ifmmode^\circ\else\te…
Polymer Halide Perovskites-Waveguides Integrated in Nanocellulose as a Wearable Amplifier-Photodetector System
2018
Semiconductor organometallic halide (CH 3 NH 3 PbX 3 , X=Cl, Br, I) perovskites (MHP) have emerged as a very high promising material for optoelectronics. Their large absorption coefficients, high electronic mobilities, excellent quantum yield of emission at room temperature and tunable band-gap with the composition resulted in a new generation of photovoltaics and electronic devices. In this work, HPVK materials are successfully incorporated on a nanocellulose (NC) substrate with the intention to exploit the interesting properties of HPVK materials to construct wearable devices. In particular, a bilayer Poly(methyl methacrylate) /HPVK deposited on NC resulted in a suitable waveguide to demo…
Formation of mono- and diglucuronides and other glycosides of benzo(a)pyrene-3,6-quinol by V79 cell-expressed human phenol UDP-glucuronosyltransferas…
1995
Glucuronidation of quinols of polycyclic aromatic hydrocarbons (PAHs) represents an important detoxication pathway preventing toxic quinone/quinol redox cycles. Therefore, mono- and diglucuronide formation of benzo(a)pyrene-3,6-quinol was investigated and compared to that of structurally related 3,6-dihydroxychrysene and simple phenols (1-naphthol and 4-methylumbelliferone) using V79 cell-expressed human UGT1.6 (= P1) and human UGT1.7 (= P4). Properties of human UGT1.6 were compared to those of the rat ortholog. Cofactors related to UDP-glucuronic acid such as UDP-galacturonic acid and UDP-glucose were also studied. It was found that rat and human UGT1.6 and human UGT1.7 catalyse monoglucur…
GH57 amylopullulanase from Desulfurococcus amylolyticus JCM 9188 can make highly branched cyclodextrin via its transglycosylation activity.
2018
Abstract Desulfurococcus amylolyticus is an anaerobic and hyperthermophilic crenarchaeon that can use various carbohydrates as energy sources. We found a gene encoding a glycoside hydrolase family 57 amylolytic enzymes (DApu) in a putative carbohydrate utilization gene cluster in the genome of D. amylolyticus . This gene has an open reading frame of 1,878 bp and consists of 626 amino acids with a molecular mass of 71 kDa. Recombinant DApu (rDApu) completely hydrolyzed pullulan to maltotriose by attacking α-1,6-glycosidic linkages, and was able to produce glucose and maltose from soluble starch and amylopectin. Although rDApu showed no activity toward α-cyclodextrin (CD) and β-CD, maltooctao…
Macrofungal diversity and ecology in two Mediterranean forest ecosystems.
2014
The macrofungal species richness and community assemblages in Italian native woodlands of oaks and Carpinus betulus and non-native woodlands of Pinus spp., Cupressus sempervirens and Eucalyptus camaldulensis were examined through the collection of basidiomata and ascomata over 1 year. The sampling in Collestrada (Umbria) and Pizzo Manolfo (Sicily) forests revealed 216 species of macrofungi. The results indicate differences in macromycete richness and diversity patterns between the two sites. The dominant tree species of the two sites were different; thus, the Collestrada forests had higher mycorrhizal species richness, while the Pizzo Manolfo forest had a higher relative number of saprotrop…