Search results for "Alpha"
showing 10 items of 3228 documents
Alpha-(13′-hydroxy)-6-hydroxychroman, the main product of alpha-tocopherol metabolism in human hepatocytes, regulates CYP4F2 and PPAR-γ expression
2017
The enzymatic metabolism of vitamin E in liver cells generates long chain metabolites (LCMs) with proposed regulatory activity on inflammatory and atherogenic genes. In this study the LCM formation kinetics was characterized in HepG2 and HepaRG human hepatic cells, supplemented with RRR-α-tocopherol (α-TOH). α-13’OH was the main product of α-TOH metabolism, while α-13’COOH metabolite and the short chain metabolite α-CEHC, were detected only in traces, thus demonstrating the poor efficiency of vitamin E catabolism in these cells. However, this metabolism was significantly simulated when the hepatic cells were challenged with (lipo)toxic agents, such as ethanol or palmitate. Under such condit…
Inhibition of cyclodextrins on α-galactosidase.
2017
This work successfully investigated the effects of different influential factors and hydrophobic cavities of cyclodextrins (CDs) on α-galactosidase (α-Gal) by detecting α-Gal activity. The highest inhibitory concentration of three kinds of CDs (α-, β-, and γ-CD) on α-Gal was 10mM. Moreover, the highest inhibition of α-Gal was obtained under the following conditions: reaction time of 90min, temperature of 30°C, and pH 6.0. Compared with other CDs, β-CD showed more ability to interact with α-Gal due to its appropriate cavity geometric dimensions. From circular dichroism and nuclear magnetic resonance it was observed that β-CD changed the secondary structure of α-Gal and formed a hydrogen bond…
Influence of the hydrophilic face on the folding ability and stability of α-helix bundles: relevance to the peptide catalytic activity
2000
Although not the sole feature responsible, the packing of amino acid side chains in the interior of proteins is known to contribute to protein conformational specificity. While a number of amphipathic peptide sequences with optimized hydrophobic domains has been designed to fold into a desired aggregation state, the contribution of the amino acids located on the hydrophilic side of such peptides to the final packing has not been investigated thoroughly. A set of self-aggregating 18-mer peptides designed previously to adopt a high level of alpha-helical conformation in benign buffer is used here to evaluate the effect of the nature of the amino acids located on the hydrophilic face on the pa…
Determination of optical purity of phosphonic acid analogues of aromatic amino acids by capillary electrophoresis with alpha-cyclodextrin.
2000
A simple and efficient method for the determination of enantiomeric purity of structurally diverse phosphonic and phosphinic acid analogues of phenylalanine and phenylglycine using capillary electrophoresis is presented. These preliminary studies indicated that the enantiomer separation is strongly dependent on the structure of the aminophosphonic acid.
Hypusinated eIF5A is required for the translation of collagen.
2021
ABSTRACT Translation of mRNAs that encode peptide sequences with consecutive prolines (polyproline) requires the conserved and essential elongation factor eIF5A to facilitate the formation of peptide bonds. It has been shown that, upon eIF5A depletion, yeast ribosomes stall in polyproline motifs, but also in tripeptide sequences that combine proline with glycine and charged amino acids. Mammalian collagens are enriched in putative eIF5A-dependent Pro-Gly-containing tripeptides. Here, we show that depletion of active eIF5A in mouse fibroblasts reduced collagen type I α1 chain (Col1a1) content, which concentrated around the nuclei. Moreover, it provoked the upregulation of endoplasmic reticul…
Impact of Reactive Oxygen Species on the Expression of Adhesion Molecules in Vivo
2008
Many non-surgical tumor treatments induce reactive oxygen species (ROS) which result in cell damage. This study investigated the impact of ROS induction on the expression of adhesion molecules and whether alpha-tocopherol pre-treatment could have a protective effect. Experimental rat DS-sarcomas were treated with a combination of localized 44 degrees C-hyperthermia, inspiratory hyperoxia and xanthine oxidase which together lead to a pronounced ROS induction. Further animals were pre-treated with alpha-tocopherol. The in vivo expression of E- and N-cadherin, alpha-catenin, integrins alpha v, beta 3 and beta 5 as well as of the integrin dimer alpha v beta 3 was assessed by flow cytometry. The…
Glassy dynamics of simulated polymer melts: Coherent scattering and van Hove correlation functions
2001
Whereas the first part of this paper dealt with the relaxation in the β-regime, this part investigates the final relaxation (α-relaxation) of a simulated polymer melt consisting of short non-entangled chains in the supercooled state above the critical temperature of ideal mode-coupling theory (MCT). The temperature range covers the onset of a two-step relaxation behaviour down to a temperature merely 2% above . We monitor the incoherent intermediate scattering function as well as the coherent intermediate scattering function of both a single chain and the melt over a wide range of wave numbers q. Upon approaching the coherent α-relaxation time of the melt increases strongly close to the max…
Cavernolide
2000
Abstract The inhibitory effect of cavernolide, a novel C 21 terpene lactone isolated from the sponge Fasciospongia cavernosa , on PLA 2 and other enzyme activities involved in the inflammatory process was studied. Cavernolide inhibited human synovial sPLA 2 in a concentration-dependent manner with an IC 50 value of 8.8 μM. Besides, this compound decreased in the nanomolar range the myeloperoxidase degranulation process using different stimuli. Cavernolide also inhibited TNFα, NO and PGE 2 production in intact cell experiments. NO and PGE 2 reduction was the consequence of the inhibition on iNOS and COX-2 expression because it did not affect inducible nitric oxide synthase and cyclooxygenase…
Intra-Helical Salt Bridge Contribution to Membrane Protein Insertion.
2021
ABSTRACTSalt bridges between negatively (D, E) and positively charged (K, R, H) amino acids play an important role in protein stabilization. This has a more prevalent effect in membrane proteins where polar amino acids are exposed to a very hydrophobic environment. In transmembrane (TM) helices the presence of charged residues can hinder the insertion of the helices into the membrane. This can sometimes be avoided by TM region rearrangements after insertion, but it is also possible that the formation of salt bridges could decrease the cost of membrane integration. However, the presence of intra-helical salt bridges in TM domains and their effect on insertion has not been properly studied ye…
Oxygen in Medicine
2010
The implications of oxygen for medicine are basically of two kinds. First, there is the continued need by human tissues for an adequate supply of dioxygen; if that is not met, a condition called hypoxia may arise, with serious medical consequences. There are a wide number of causes for hypoxia, and a variety of medical responses.