Search results for "Arabinose"
showing 5 items of 15 documents
Extraction, Structural Characterisation, and Immunomodulatory Properties of Edible Amanita hemibapha subspecies javanica (Corner and Bas) Mucilage Po…
2021
This research aimed to extract mucilage polysaccharides (MP) from Amanita hemibapha subspecies javanica (Corner and Bas), and further fractionate them using anion-exchange chromatography, yielding two fractions (MPF1 and MPF2). The crude extract, and fractions mainly consisted of carbohydrates (83.5–93.2%) with minor amounts of proteins (5.40–7.20%), and sulphates (1.40–9.30%). Determination of the monosaccharide composition revealed that glucose was the major unit, followed by galactose, mannose, rhamnose, and arabinose. The average molecular weight (MW) of the crude extract and fractions was in the range 104.0–479.4 × 103 g/mol. Interestingly, the crude extract, and fractions did not caus…
The dnaK operon of Streptomyces coelicolor encodes a novel heat-shock protein which binds to the promoter region of the operon
1995
Transcriptional studies have demonstrated that the dnaK gene of Streptomyces coelicolor A3(2) is contained within a 4.3 kb operon. The operon is transcribed from a single (transiently) heat-inducible promoter, dnaKp, that resembles the typical vegetative (sigma 70-recognized) eubacterial consensus promoter sequence. dnaK transcription was found to be heat-inducible at all stages of development in surface-grown cultures. In addition, at the normal growth temperature of 30 degrees C, dnaK transcript levels were shown to vary at different stages of development, being more abundant in young germinating cultures and in mycelium undergoing sporogenesis. The nucleotide sequence of the dnaK operon …
Water-soluble polysaccharides from Opuntia stricta Haw. fruit peels: Recovery, identification and evaluation of their antioxidant activities
2015
Abstract Opuntia stricta Haw. is considered as one of the most common cactus plant growing in Tunisia. Extracting valuable compounds from its fruit peel, considered as by-product, is drawing more and more attention, making it on the verge of commercialization. Water-soluble polysaccharides were extracted from Opuntia stricta Haw. peels, and their chemical composition assessed using thin layer chromatography. The antioxidant activities of the extracted polysaccharides were assessed using 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity, total antioxidant activity and reducing power capacity. The extraction yield of water-soluble polysaccharides was 7.53±0.86%. The chemical comp…
Hemicellulose hydrolysis catalysed by solid acids
2013
Depolymerising hemicellulose into platform sugar molecules is a key step in developing the concept of an integrated biorefinery. This reaction is traditionally catalysed by either enzymes or homogeneous mineral acids. We compared various solid catalysts for hemicellulose hydrolysis, running reactions in water, under neutral pH and relatively mild temperature and pressure (120°C and 10 bar) conditions. Sulphonated resins are highly active, but they leach out sulphonic groups. Sulphonated silicas are less active, but more stable. They have weakly and strongly bound sites and the strongly bound ones do not leach. Zeolites are moderately active and stable. Among them, H-ferrierite especially, d…
l-Arabinose Conformers Adsorption on Ruthenium Surfaces: A DFT Study
2012
Adsorption of 5 L-arabinose tautomers – one acyclic and four cyclic (α and β, pyranose and furanose) species – on a ruthenium surface was studied as a precursor-process of the, nowadays more and more, industrially important sugar catalytic hydrogenation on metal surfaces in water medium. The study was mostly referred to a 37-atom metal catalyst fragment, even though border-effects on the adsorption processes were also checked employing a 61-atom metal fragment. In order to figure out conformational effects on the title process the tautomer flexibility was, at first, investigated by the genetic-algorithm based code Balloon, considering the conformational spaces of the different aquo tautomer…