41,137 research outputs found
Structure analysis of methyl a-L-fucopiranoside by X-ray crystallography, NMR spectroscopy and molecular mechanics calculations
No full textCooperating Agents for 3D Scientific Data Interpretation
No full textMany organizations collect vast quantities of three-dimensional (3-D) scientific data in volumetric form for a range of purposes, including resource exploration, market forecasting, and process modelling. Traditionally, these data have been interpreted by human experts with only minimal software assistance. However, such manual interpretation is a painstakingly slow and tedious process. Moreover, since interpretation involves subjective judgements and each interpreter has different scientific knowledge and experience, formulation of an effective interpretation often requires the cooperation of numerous such experts. Hence, there is a pressing need for a software system in which individual interpretations can be generated automatically and then refined through the use of cooperative reasoning and information sharing. To this end, a prototype system, SurfaceMapper, has been developed in which a community of cooperating software agents automatically locate and display interpretations in a volume of 3-D scientific data. The challenges and experiences in designing and building such a system are discussed. Particular emphasis is given to the agents' interactions and an empirical evaluation of the effectiveness of different cooperation strategies is presented
Structure elucidation of methyl 3,4-O-isopropilidene-a- and b-D-galactopyranosides by NMR and X-ray analysis
No full textThe authors report the structure of methyl 3,4-O-isopropylidene-α-and -β-D-galactopyranosides. A knowledge of the conformational features of these compounds will contribute to the interpretation of the marked difference of reactivity toward t-BuOK. Both NMR and x ray analyses were performed
Efficient folding of the FcεRI α-chain membrane-proximal domain D2 depends on the presence of the N-terminal domain D1
No full textHuman high affinity receptor for IgE is a membrane glycoprotein multi-chain complex presenting two extracellular Ig modules in its α-chain (D1D2). The receptor IgE binding region is located within the membrane-proximal module D2, while the N-terminal module D1 appears to promote an optimal receptor conformation for IgE binding. To understand the structural relationship between the two modules, we dissected FcεRI α-chain into its discrete Ig units and expressed them in mammalian cells. Unexpectedly, D2 was secreted as a disulphide-linked dimer, while D1 was monomeric. Active secretion and full glycosylation of dimeric D2 suggest a native-like conformation of the protein, justifying the escape from the endoplasmic reticulum/Golgi quality control systems. We then propose a domain-swapping model for D2, in which two interdigitated polypeptide chains assume the overall conformation of two Ig modules, as observed for rat CD2 N-terminal domain. Fusion of an unrelated Ig fold moiety at the N terminus of D2 did not interfere with its dimerisation. While D1D2 assumes a correct fold, co-expression of both isolated domains in the same cell did not restore monomeric folding of D2. Thus, D1 appears to assist the appropriate folding of FcεRI α-chain, acting as an uncleavable intramolecular chaperone-like block towards D2. © 2002 Elsevier Science Ltd. All rights reserved
Long chain analogs of physostigmine as potential drugs for Alzheimer's disease: new insights into mechanism of action in the inhibition of acetylcholinesterase
No full textHeptylphysostigmine is in advanced clinical trial as a drug for Alzheimer's disease. 8-Morpholinooctylphysostigmine and 8-(cis-2,6-dimethylmorpholino)octylphysostigmine are currently undergoing pre-clinical evaluation. The mechanism of action of these compounds in the inhibition of acetylcholinesterase has been investigated. All the examined compounds display non competitive-like kinetics of inhibition. There are no reversible components in the observed inhibition: the whole inhibitory effect is due to the time-dependent pseudo-irreversible carbamylation of the active site. Yet the observed time course of the inhibition does not match a simple second order kinetics. An influence of the quaternary structure of the enzyme on the more complex kinetics of carbamylation is hypothesized. Reactivation experiments on the inhibited enzyme show long lasting inhibitory effects for these compounds. The higher duration of the anticholinesterase effect of the morpholino derivatives compared to heptylphysostigmine should provide the basis for their higher therapeutic potential
2-substituted 3-aryl- and 3-heteroarylindoles by the palladium-catalyzed reaction of o-trifluoroacetanilides with aryl bromides and triflates
No full textThe palladium-catalyzed reaction of aryl and heteroaryl bromides and triflates with o-alkynyltrifluoroacetanilides affords 2-substituted 3-aryl- and heteroarylindoles usually in excellent yield. The procedure can be applied to the synthesis of 2-substituted indole-3-carboxaldehydes
Chondroprotective action of chondroitin sulfate. Competitive action of chondroitin sulfate on the digestion of hyaluronan by bovine testicular hyaluronidase
No full textIsolation and quantitation of hyaluronan tetra- and hexasaccharide by anion exchange HPLC
No full textQuality Characteristics of Lamba as Affected by Different Cereal and Legume Flour Blends
No full textTraditional foods are preserved cultural heritage passed down from generation to generation, and their recipes have remained unchanged for centuries. Lamba is a traditional food processed from the blends of maize, cowpea and karkashi (false sesame leaves). However, if prepared and consumed, lamba enriched with different flour blends will provide a healthy alternative to consumers. This study aimed to prepare and evaluate the quality of lamba produced from wheat – cowpea – karkashi (Wck), wheat– soybeans – karkashi (Wsk) and lastly, wheat –bambara groundnut– karkashi (wbk) flour blends in three different ratios, (70:20:10, 60:30:10 and 50:40:10) where maize-cowpea -karkashi (Mck) is the control (in the ratio of 70:20:10). The total of ten (10) different samples were produced including the control. Proximate composition, functional and microbial content of lamba samples were determined. The proximate composition of the lamba such as moisture, protein, fat, ash, crude fiber and carbohydrate ranged from .40 –9.92%, 7.92 – 15.39%, 3.82 – 9.25%, 2.78 – 3.48%, 2.03 – 3.55% and 64.24 – 73.55% respectively. Subsequently, there are significant differences (p≤0.05) between the functional properties such as wettability, bulk density, water absorption capacity and swelling index of the flour blends which ranged from 50.13 – 68.18 sec, 0.60 – 0.76 g/ml, 58.93 – 105.58 %, 1.36 – 2.15% respectively. Also, wettability, bulk density, water absorption capacity and swelling index have been determined and the control sample (Mck) had the highest. Similarly, microbiological analysis shows the bacterial load ranged from 4.9 ×104 – 8.1 × 104 cfu/g and sample Wbk 3 had the highest Mck (control sample) had the lowest. However, there was no significant difference between all the remaining samples. additionally, fungal load ranged from 1.6 × 10 5 – 4.4 × 105 cfu/g and sample Wsk 2 had the highest fungal count while sample Wbk 3 had the lowest. Sensory attributes of lamba were evaluated ranging from 5.09 – 6.13 for texture, 5.01– 6.38 for aroma, 4.92 – 7.98 for taste, 4.61 – 6.08 for colour and 5.18 – 8.49 for overall acceptability. The study shows that lamba produced from different ratio of wheat, soybean, cowpea, bambara groundnut and karkashi contains higher nutritive value. It is also acceptable as compared to lamba produced from maize, cowpea and karkashi. Therefore, this study recommends that the blend of 60% wheat, 30% soybeans and 10% karkashi (Wsk 2) can be used for the production of lamba with the desired nutritional and sensory quality as alternative to soybean
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