Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
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Although smooth muscle and endothelial cells in pig coronary artery are morphologically and functionally distinct, ascorbate uptake has been characterized only in smooth muscle cells. Ascorbate transporters in kidney and intestinal epithelial cells differ from those in smooth muscle. We examined ascorbate transport and mRNA expression of sodium-dependent vitamin C transporters (SVCT) by RT-PCR in the pig coronary artery endothelial cell cultures. When 14C-ascorbate uptake in endothelial cells was examined as 14C or by HPLC, the two values did not differ from each other. 14C-ascorbate uptake was Na(+)-dependent, stereoselective for L-ascorbate and inhibited by sulfinpyrazone. The kinetic characteristics of the uptake were: Km = 27 +/- 3 microM (Hill coefficient = 1) for ascorbate and Km = 73 +/- 14 mM (Hill coefficient = 2) for Na+. Surprisingly, endothelial cells had similar kinetic parameters as smooth muscle cells, except for a slightly lower uptake velocity in endothelial cells. Comparison with the smooth muscle showed that both tissue types expressed mRNA for SVCT2. Endothelial cells differ from epithelial cells which express mainly SVCT1 but resemble smooth muscle cells in this respect.
Mol Cell Biochem 2005 Mar
PMID:Ascorbate uptake in pig coronary artery endothelial cells. 1588 54

We compared the interactions of purines and purine analogues with representative fungal and bacterial members of the widespread Nucleobase-Ascorbate Transporter (NAT) family. These are: UapA, a well-studied xanthine-uric acid transporter of A. nidulans, Xut1, a novel transporter from C. albicans, described for the first time in this work, and YgfO, a recently characterized xanthine transporter from E. coli. Using transport inhibition experiments with 64 different purines and purine-related analogues, we describe a kinetic approach to build models on how NAT proteins interact with their substrates. UapA, Xut1 and YgfO appear to bind several substrates via interactions with both the pyrimidine and imidazol rings. Fungal homologues interact with the pyrimidine ring of xanthine and xanthine analogues via H-bonds, principally with N1-H and =O6, and to a lower extent with =O2. The E. coli homologue interacts principally with N3-H and =O2, and less strongly with N1-H and =O6. The basic interaction with the imidazol ring appears to be via a H-bond with N9. Interestingly, while all three homologues recognize xanthines with similar high affinities, interaction with uric acid or/and oxypurinol is transporter-specific. UapA recognizes uric acid with high affinity, principally via three H-bonds with =O2, =O6 and =O8. Xut1 has a 13-fold reduced affinity for uric acid, based on a different set of interactions involving =O8, and probably H atoms from positions N1, N3, N7 or N9. YgfO does not recognize uric acid at all. Both Xut1 and UapA recognize oxypurinol, but use different interactions reflected in a nearly 26-fold difference in their affinities for this drug, while YgfO interacts with this analogue very inefficiently.
Mol Membr Biol
PMID:Comparative substrate recognition by bacterial and fungal purine transporters of the NAT/NCS2 family. 1609 68

In a system which consisted of luminol (3-aminophthalhydrazide), cobalt sulfate (CoSO4), alkaline buffer and the mixture of NaSO3 and sodium bisulfite (NaHSO3) (sulfite and bisulfite=3:1, m/m), a strong chemiluminescence (CL) was observed using a BPCL ultra-weak luminometer. The CL signals resulted from 3-aminophthalate (the product of oxidized luminol), and were affected by the buffer pH, buffer medium and the concentrations of luminol, CoSO4 and the NaSO3-NaHSO3 mixture. The observation that the CL intensities were inhibited by superoxide dismutase (SOD), Vitamin C (Vc) and glutathione (GSH) in a dose-dependent manner suggested that superoxide radical (O2*-) was involved in the CL reaction and responsible for oxidation of luminol.
Spectrochim Acta A Mol Biomol Spectrosc 2006 May 01
PMID:Inhibition of superoxide dismutase, Vitamin C and glutathione on chemiluminescence produced by luminol and the mixture of sulfite and bisulfite. 1615 Jun 38

The present investigation was carried out to evaluate the antioxidant nature of ethanolic extract of Terminalia arjuna bark (EETA) on N-nitrosodiethylamine (DEN) induced liver cancer in male Wistar albino rats. Liver cancer was induced by single intraperitonial injection of DEN (200 mg/kg). After 2 weeks of DEN administration, Phenobarbital (PB) was given to promote the cancer for up to 14 successive weeks. EETA extract (400 mg/kg) was given post-orally for 28 days to hepatocellular carcinoma-bearing rats. After the experimental period, all the animals were sacrificed and serum, liver and kidney samples were collected for further biochemical analysis. The levels of lipid peroxides (LPO) under basal and also in the presence of inducers (H(2)O(2), ascorbate and FeSO(4)) were estimated in serum, liver and kidney of control and experimental animals. Enzymic antioxidants, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and non-enzymic antioxidants like Vitamin C (Vit-C) and Vitamin E (Vit-E) levels were determined in all the groups of animals. A significant increase in LPO levels were observed while the levels of enzymic and non-enzymic antioxidants were decreased, when subjected to DEN induction. These altered enzyme levels were ameliorated significantly by administration of EETA at the concentration of 400 mg/kg in drug-treated animals. This protective effect of EETA was associated with inhibition of LPO induced by DEN and to maintain the antioxidant enzyme levels. Our results show an antioxidant activity of T. arjuna bark against DEN-induced liver cancer.
Mol Cell Biochem 2006 Jan
PMID:Antioxidant activity of Terminalia arjuna bark extract on N-nitrosodiethylamine induced hepatocellular carcinoma in rats. 1632 60

A new solid substrate-room temperature phosphorescence quenching method for the determination of trace copper has been established. It is based on the fact that beryllon (R) can emit strong and stable solid substrate-room temperature phosphorescence on the filter paper, and Vitamin C (Vc) reduces R to non-phosphorescent compound that leads to solid substrate-room temperature phosphorescence (SS-RTP) quenching of R, and alpha,alpha'-dipyridyl can activate copper catalyzing Vitamin C reducing R. The DeltaI(p) of the system with alpha,alpha'-dipyridyl is 3.3 times higher than that without alpha,alpha'-dipyridyl, which shows the reaction of alpha,alpha'-dipyridyl activating copper catalyzing Vitamin C reducing R. The reducing value of phosphorescence intensity (DeltaI(p)) is directly proportional to the content of Cu(II) in the range of 0.040-4.0 fg spot(-1) (corresponding concentration: 0.10-10.0 pg ml(-1), sample volume: 0.40 microlspot(-1)). The regression equation of working curve can be expressed as DeltaI(p)=69.99+41.00 m Cu(2+) (fg spot(-1)) (r=0.9980, n=6), and the detection limit is 0.0088 fg spot(-1)(corresponding concentration: 2.2 x 10(-14) g ml(-1)). This sensitive and accurate method with good repeatability and high selectivity has been applied to the determination of trace copper in real samples with satisfactory results. The reaction mechanism for the determination of trace copper by solid substrate-room temperature phosphorescence quenching method based on the activating effect of alpha,alpha'-dipyridyl on Vitamin C reducing beryllon is also discussed.
Spectrochim Acta A Mol Biomol Spectrosc 2006 Jul
PMID:Determination of trace copper by solid substrate-room temperature phosphorescence quenching method based on activating effect of alpha,alpha'-dipyridyl on Vitamin C reducing beryllon. 1633 48

The vibrational characteristics (vibrational frequencies, infrared intensities and Raman activities) for the hydrogen-bonded system of Vitamin C (L-ascorbic acid) with five water molecules have been predicted using ab initio SCF/6-31G(d,p) calculations and DFT (BLYP) calculations with 6-31G(d,p) and 6-31++G(d,p) basis sets. The changes in the vibrational characteristics from free monomers to a complex have been calculated. The ab initio and BLYP calculations show that the complexation between Vitamin C and five water molecules leads to large red shifts of the stretching vibrations for the monomer bonds involved in the hydrogen bonding and very strong increase in their IR intensity. The predicted frequency shifts for the stretching vibrations from Vitamin C taking part in the hydrogen bonding are up to -508 cm(-1). The magnitude of the wavenumber shifts is indicative of relatively strong OH...H hydrogen-bonded interactions. In the same time the IR intensity and Raman activity of these vibrations increase upon complexation. The IR intensity increases dramatically (up to 12 times) and Raman activity increases up to three times. The ab initio and BLYP calculations show, that the symmetric OH vibrations of water molecules are more sensitive to the complexation. The hydrogen bonding leads to very large red shifts of these vibrations and very strong increase in their IR intensity. The asymmetric OH stretching vibrations of water, free from hydrogen bonding are less sensitive to the complexation than the hydrogen-bonded symmetric OH stretching vibrations. The increases of the IR intensities for these vibrations are lower and red shifts are negligible.
Spectrochim Acta A Mol Biomol Spectrosc 2006 Feb
PMID:Theoretical study of the changes in the vibrational characteristics arising from the hydrogen bonding between Vitamin C (L-ascorbic acid) and H2O. 1642 51

In the last decade, naturally occurring antioxidants continue to play an important role in the food-supplement industry. The content of antioxidants in a plant depends on the species, temperature, humidity, period of growth, harvest month, part of the plant used and many other variables. Herein, we present a new method able to determine the all over antioxidative power (AP) of plant extracts or lyophilised plant parts based on the reducing activity against a stable test radical. The method is performed by ESR spectroscopy and is based on the well-known 1,1-diphenyl-2-picryl-hydrazil (DPPH) method with the major difference that both the antioxidative capacity and the antioxidative activity are used to characterise an antioxidant. The resulting antioxidative power is expressed in antioxidative units (AU), where 1AU corresponds to the activity of a 1 ppm solution of Vitamin C as a benchmark. This method allows a rapid, unexpensive and general applicable technique for the measurement of the antioxidative power of very different kinds of substances. The inclusion of the kinetic behaviour of the reducing process of the antioxidant for the determination of the AP allows the identification of the main antioxidant present in a sample. Herein, we present the application example of seeds, sprouts and adult parts of dandelion, amaranth, quinoa, fenugreek, broccoli, red clover and mugwort, where the AP method permits to characterise the plants with the highest antioxidant capacity and reaction velocity. The method permits to select active plant extracts for the food and nutrition industry.
Spectrochim Acta A Mol Biomol Spectrosc 2006 Mar 13
PMID:The antioxidative power AP--A new quantitative time dependent (2D) parameter for the determination of the antioxidant capacity and reactivity of different plants. 1649 Mar 83

Within the Arabidopsis family of 21 heat stress transcription factors (Hsfs) HsfA2 is the strongest expressed member under heat stress (hs) conditions. Irrespective of the tissue, HsfA2 accumulates under heat stress similarly to other heat stress proteins (Hsps). A SALK T-DNA insertion line with a complete HsfA2-knockout was analyzed with respect to the changes in the transcriptome under heat stress conditions. Ascorbate peroxidase 2 (APX2) was identified as the most affected transcript in addition to several sHsps, individual members of the Hsp70 and Hsp100 family, as well as many transcripts of genes with yet unknown functions. For functional validation, the transcription activation potential of HsfA2 on GUS reporter constructs containing 1 kb upstream promoter sequences of selected target genes were analyzed using transient reporter assays in mesophyll protoplasts. By deletion analysis the promoter region of the strongest affected target gene APX2 was functionally mapped in detail to verify potential HsfA2 binding sites. By electrophoretic mobility shift assays we identified TATA-Box proximal clusters of heat stress elements (HSE) in the promoters of selected target genes as potential HsfA2 binding sites. The results presented here demonstrate that the expression of HsfA2 in Arabidopsis is strictly heat stress-dependent and this transcription factor represents a regulator of a subset of stress response genes in Arabidopsis.
Plant Mol Biol 2006 Mar
PMID:The heat stress transcription factor HsfA2 serves as a regulatory amplifier of a subset of genes in the heat stress response in Arabidopsis. 1664 11

Powdery mildew, caused by Uncinula necator Burr, is one of the most seriously damaging diseases of grapevine all over the world. To gain the novel gene and investigate the resistance mechanism in Chinese Wild Vitis pseudoreticulata clone Baihe-35-1, mRNA differential display was employed to study the differential expression of the resistant gene to the disease of it when inoculated by Uncinula necator under natural field conditions, 5' RACE and 3' RACE have been used to clone the whole cDNA sequences of VpAPX, the novel gene related to Ascorbate Peroxidase which involved in resistant to the disease, is composed of specific sequence 1077 bp and has an open reading frame of 750 bp coding for 250 amino acid residues with a molecular weight of 27.566 kDa. The VpAPX gene was obtained by polymerase chain reaction (PCR) with the special primers synthesized according to the sequences of cDNA, and further cloned it into the pGEM-T easy vector. The cloned VpAPX gene was cut out again with two restriction enzymes and was inserted into the prokaryotic expression vector pGEX-4T-1, then transferred into E. coli BL21. As result, GST-VpAPX fusion protein was successfully expressed by induction of IPTG and purified by GST affinity resin. After injecting rabbit, the polyclonal antibodies were produced. Western blot analyses showed that the antibody reacted specifically to GST-VpAPX fusion protein and the titer for this antibody is 10(5). This research made the foundation to transform the VpAPX gene into grape plants for follow research in processing.
Mol Biol Rep 2006 Sep
PMID:cDNA clone, fusion expression and purification of the novel gene related to ascorbate peroxidase from Chinese wild Vitis pseudoreticulata in E. coli. 1685 Jan 89

Vitamin C is a major antioxidant and UV absorbent in the human lens. In the rodent lens, the levels are very low for unknown reasons. Searching for clues to explain this suppression, we investigated the comparative uptake of Vitamin C in cultured human and mouse lens epithelial cells. When compared to human HLE-B3 lens epithelial cells, (14)C-ASA uptake was 4- to 10-fold impaired in confluent mouse lens 17EM15 (p < 0.0001) and 21EM15 (p < 0.001) cells, respectively. High glucose concentrations reduced the uptake by 30-50% in all cells (p < 0.005). Incubation of cells with 6-deoxy-6-fluoro-ascorbic (F-ASA), i.e. a probe specific for the sodium-dependent Vitamin C uptake (SVCT2), revealed a 10-fold uptake suppression into mouse 17EM15 relative to human HLE-B3 and JAR choriocarcinoma cells (a control), that could be overcome by overexpressing hSVCT2 using two different promoter constructs. The relative Vitamin C uptake differences suggest either low expression of SVCT2, molecular differences between the transporters themselves or their biological regulation, since a recent study has shown that exogenous feeding of ascorbic acid to rats increased only modestly lenticular uptake (Mody et al., Acta Ophthalmol Scand 83: 228-223, 2005). Elucidation of the mechanism by which SCVT2 activity is suppressed in mouse lens may help unravel a major question of evolutionary significance for night vision in nocturnal animals.
Mol Cell Biochem 2006 Dec
PMID:Relative suppression of the sodium-dependent Vitamin C transport in mouse versus human lens epithelial cells. 1693 33


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