Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:EXPT00568 (ascorbate)
 23,072 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The field experiment was conducted to study the effect of various levels of chlormequat (CCC) and alar on the biochemical changes in tomato plants and fruits at different stages of growth. This experiment included spraying with chlormequat and alar separately in two equal doses (250, 500 and 1000 ppm CCC or alar 25 and 40 days after transplanting). The different levels of chlormequat decreased the accumulation of dry matter in tomato plants, but alar increased it. Chlorophyll a, b, total chlorophyll and carotenoids content of tomato plants increased by the application of CCC or alar. The highest increase of concentration of chlorophyll a, b and carotenoids in tomato plants were found by spraying with 500 ppm alar or CCC. The application of CCC and alar declined the percentage of carbohydrates and the highest decrease resulted by adding of 1000 ppm alar or CCC. Alar caused an increase in the percentage of total nitrogen at the different stages of growth. The concentration of P, K, Ca and Mg increased by the foliar spray of all treatments. Alar application at all used levels significantly increased the yield and also the weight of fruits. Highest plant productivity was obtained by using alar and CCC at 250 ppm, followed by 500 ppm. However, the highest concentration (1000 ppm) depressed the plant productivity. The concentration of juice, total soluble solids and vitamin C in tomato fruits increased at most of the levels added. But the percentage of total sugars and total acidity seemed to exert another trend. The highest concentration of N, P, K, Ca and Mg in fruits was obtained by foliar application of 500 ppm CCC or alar.
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PMID:Effect of chlormequat and alar on some biochemical constituents in tomato plants and fruits. 400 Feb 46

A method has been developed for the extraction of proteins from green plant tissues to be used in two-dimensional polyacrylamide gel electrophoresis. Three purification steps were necessary to overcome the problems due to streaking, charge heterogeneity, and other artifacts: After it was ground in liquid nitrogen, the powdered material was stirred in the presence of insoluble polyvinylpyrrolidone for binding phenols, and sodium ascorbate for binding quinones; proteins were precipitated with ammonium sulfate, and the sample was dialyzed. Hundreds of proteins could be detected after Coomassie blue staining using 200 micrograms of proteins from apical buds of Sinapis alba L.
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PMID:Method for extraction of proteins from green plant tissues for two-dimensional polyacrylamide gel electrophoresis. 402 20

In an initial communication [May, S. W., Mueller, P. W., Padgette, S. R., Herman, H. H., & Phillips, R. S. (1983) Biochem. Biophys. Res. Commun. 110, 161-168], we reported that 1-phenyl-1-(aminomethyl)ethene hydrochloride (PAME) is an olefinic substrate for dopamine beta-monooxygenase (DBM; EC 1.14.17.1) which inactivates the enzyme in an apparent mechanism-based manner. The present study further characterizes this reaction. The inactivation reaction yields kinact = 0.23 min-1 at pH 5.0 and 37 degrees C and is strictly dependent on reductant (ascorbate) and oxygen. The DBM/PAME substrate reaction (apparent kcat = 14 s-1), shown to be stimulated by fumarate, gives the corresponding epoxide as product, identified by derivatization with 4-(p-nitrobenzyl)pyridine. However, the lack of DBM inhibition by alpha-methylstyrene oxide, and the observation of identical PAME/DBM inactivation rates in the absence and presence of preformed enzymatic PAME epoxide, indicates that free epoxide is not the inactivating species. A structure-activity study revealed that 4-hydroxylation of PAME (to give 4-HOPAME) increases both kinact (0.81 min-1) and apparent kcat (56 s-1) values, while 3-hydroxylation (to give 3-HOPAME) greatly diminishes inactivation activity while retaining substrate activity (apparent kcat = 47 s-1). 4-Hydroxy-alpha-methylstyrene was found to be a DBM inhibitor (kinact = 0.53 min-1) with weak substrate activity (apparent kcat = 0.71 s-1), while 3-hydroxy-alpha-methylstyrene and alpha-(cyanomethyl) styrene were found not to exhibit detectable DBM substrate activity and only weak inhibitory activity. 3-Phenylpropargylamine hydrochloride showed no detectable DBM substrate activity but rapidly inactivated the enzyme. A new substrate activity for DBM was discovered, N-dealkylation of N-phenylethylenediamine and N-methyl-N-phenylethylenediamine, and the lack of O-dealkylation activity with phenyl 2-aminoethyl ether and 4-hydroxyphenyl 2-aminoethyl ether indicates that DBM N-dealkylation proceeds via initial one-electron abstraction from the benzylic nitrogen heteroatom. With this new substrate and inhibitor reactivity information in hand, along with the other known substrate reactions, a DBM oxygenation mechanism analogous to that for cytochrome P-450 is proposed.
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PMID:Olefin oxygenation and N-dealkylation by dopamine beta-monooxygenase: catalysis and mechanism-based inhibition. 408 93

Cytochrome c-552 was extracted from a red alga, Polysiphonia urceolata, by immersion of the frozen trichomes in deionized water. Purification was carried out by acrinol treatment, ammonium sulfate fractionation, DEAE-Sephacel chromatography, hydroxyapatite column chromatography, and Bio-Gel P-10 gel filtration. The ferrocytochrome c-552 has absorption maxima at 551.5(alpha), 522.5(beta), 416.3(gamma), 318(delta), 292, and 270 nm; those of the ferricytochrome are at 525, 408.5(gamma), and 358 nm. The pyridine ferrohemochrome showed absorption maxima at 550(alpha), 520(beta), and 414 nm(gamma). The alpha-band of the ferrocytochrome is symmetric without any shoulder at room temperature, and does not split even at liquid nitrogen temperature. The ferricytochrome showed a weak absorption shoulder at 695 nm, suggesting a methionine sulfur to be the sixth ligand of heme c iron. The cytochrome is oxidized by ferricyanide and reduced by ferrocyanide, cysteine, ascorbate, and hydrosulfite. Autoxidation was not observed. The midpoint potential (Em) of the cytochrome was determined by equilibration with the ferro- and ferricyanide system to be 0.333 volt at pH 7.0 and 25 degrees C. The isoelectric points of the ferro- and ferricytochromes were determined to be at pH 3.85 and 4.02, respectively, by the isoelectric focusing method. The molecular weight was estimated to be about 12,000 from the results of gel filtration and SDS polyacrylamide gel electrophoresis.
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PMID:Studies on algal cytochromes. V. Purification and characterization of cytochrome c-552 from a red alga, Polysiphonia urceolata. 609 51

The NADH-dependent nitrite reductase of Escherichia coli, which contains sirohaem, flavin, non-haem iron and labile sulphide, was examined by low-temperature e.s.r. spectroscopy. The enzyme, stored in the presence of nitrite and ascorbate, gave the spectrum of a nitrosyl derivative, with hyperfine splitting due to the nitrosyl nitrogen. On removal of these reagents, a series of signals centred around g = 6 was observed, typical of high-spin ferric haem. Cyanide converted this into a low-spin form. On reduction of the enzyme with NADH, an axial spectrum at g = 1.92, 2.01 was observed. The temperature-dependence of this signal is indicative of a [2Fe-2S] iron-sulphur cluster. The midpoint potential of this cluster was estimated to be -230 +/- 15 mV by two independent methods. Reduction of the enzyme with dithionite yielded further signals, which are at present unidentified, at g = 2.1-2.28. No signals were observed that could be assigned to a [4Fe-4S] cluster, such as is found in other sulphite reductases and nitrite reductases that contain sirohaem.
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PMID:Electron-spin-resonance studies of the NADH-dependent nitrite reductase from Escherichia coli K12. 629 58

Storage of milk powder under unfavourable conditions accelerates the normally slow deterioration in nutritional quality. The effects of such storage on the water-soluble vitamin composition were examined. (a) Spray-dried whole milk containing 25 g water/kg was stored at 60 degrees and 70 degrees and sampled weekly to 9 weeks. (b) Spray-dried whole milk and skimmed milk were adjusted to contain 40 and 100 g water/kg and stored at 37 degrees in nitrogen and in oxygen. Samples were taken for analysis at intervals during storage. The samples were analysed for eight B-complex vitamins and ascorbic acid, and also for total lysine, 'reactive lysine' and 'lysine as lactulosyl-lysine'. Storage at 60 degrees caused rapid destruction of folic acid (53% loss at 4 weeks) and slower loss of thiamin, vitamin B6 and pantothenic acid (18% at 8 weeks). There was no change in the content of riboflavin, biotin, nicotinic acid and vitamin B12. At 70 degrees the rate of destruction of the four labile vitamins was much increased; 18% or less survived at 4 weeks. At 37 degrees and 40 g water/kg there was little change in total and 'reactive' lysine during storage for 57 d. Lactulosyl-lysine was demonstrably present but at low concentration. There was considerable loss of folate (72%) and ascorbate (91%) during storage for 30 d in O2, but no significant loss in N2. Thiamin fell by approximately 12% in 57 d, equally in O2 and N2. The content of the remaining vitamins was unchanged. At 100 g water/kg there were progressive Maillard changes. During 27 d in N2 the colour changed from cream to pale brown, but in O2 there was no perceptible colour change. Total lysine fell by 20% in 27 d, and 'reactive lysine' by 30%. Folate was stable during 16 d in N2, but largely (94%) destroyed in O2. Ascorbic acid was also destroyed in N2 as in O2. Thiamin fell by 41% in 27 d, equally in O2 and N2. Vitamin B6 was more labile, especially in N2, falling by 71% in 16 d. With skimmed-milk powder containing 100 g water/kg, storage at 37 degrees in O2 and N2 gave much the same results as for the corresponding whole-milk powder. The presence of milk fat had no marked effect on the stability of the water-soluble vitamins. Destruction of vitamins was clearly linked to the progress of Maillard-type reactions and was strongly influenced by time and temperature of storage, moisture content and, in some instances, by the presence of O2.
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PMID:Storage of milk powders under adverse conditions. 2. Influence on the content of water-soluble vitamins. 640 21

Throughout adult life, there is progressive alteration in body composition and tissue function. There is loss of lean body mass, notably by muscle, with a gain in body fat. We do not know whether nutritional factors affect these gross changes. In the case of loss of bone density (osteoporosis), however, there is evidence that the process is retarded by raising the intake of calcium and by exercise. Aging also adversely affects tissue function at the level of the whole organ and tissue as well as at the cellular and subcellular level. Animal models show similar age-related changes, and demonstrate further that alterations in nutrient intake or exercise can alter the rate of loss of tissue and cellular function. In addition to the effects of adult aging on tissue function, certain chronic diseases and disabilities are related to aging. These conditions include atherosclerosis, hypertension, coronary thrombosis, cancer, etc. Both human epidemiological studies and animal experiments on aging suggest strongly that nutrition plays a role in the onset and development of these conditions. There is a need for more accurate assessments of the nutrient needs of people over 65 years of age. A few selected nutrients are discussed. Studies of energy intake during adult life show a progressive reduction with increasing age, due mainly to reduced physical activity. Vitamin C levels in the white blood cells of elderly women can be half those of young adults; these respond to supplementary vitamin C without evidence of clinical benefit. Nitrogen balance studies suggest that the allowance of protein for older adults is not less than for young. Finally, surveys of elderly in whole populations and in selected groups show that, by the nutritional standards of young adults, there may exist a significant amount of malnutrition in people as they grow old, though we do not know whether this affects rate of loss of tissue function with age.
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PMID:Nutrition and the elderly: a general overview. 650 37

Sex- and age-related differences in dietary and blood chemistry factors were investigated in subjects adhering to their usual lifestyles. Diet records were examined daily and blood chemistry profiles were monitored five times during the 1-yr study. As expected, high-density lipoprotein cholesterol was significantly higher in women than in men. Values of creatine phosphokinase, aspartic aminotransferase, alanine aminotransferase, glucose, triglycerides, urea nitrogen, uric acid, and total bilirubin were higher in men than in women. Glucose was lower while high-density lipoprotein cholesterol, albumin, and total protein were higher in the younger women than in older women. Alcohol consumption by men correlated positively with aspartic aminotransferase and alanine aminotransferase but not with high-density lipoprotein cholesterol. Alcohol consumption by women did correlate positively with high-density lipoprotein cholesterol but not with the aminotransferase enzymes. Correlations between serum high-density lipoprotein cholesterol and vitamin C intake were positive and significant in women. In men, high levels of high-density lipoprotein cholesterol seems to be associated with very high vitamin C intakes, but no associations were apparent at normal levels of these parameters. Serum cholesterol did not correlate significantly with dietary cholesterol, saturated fat, linoleic acid, or P/S in men or women.
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PMID:Relationships among dietary constituents and specific serum clinical components of subjects eating self-selected diets. 650 55

Inhalation of nitrogen dioxide (NO2) by mice administered orally morpholine (MOR) or dimethylamine (DMA) resulted in the biosynthesis of N-nitrosomorpholine (NMOR) or N-nitrosodimethylamine (NDMA), respectively, as determined by the analysis of frozen whole-mouse powder, using gas chromatography with a Thermal Energy Analyzer detector. Significant levels of NMOR were detected following exposure of mice to 0.38 mg/m3 NO2 for 0.5 h (26 ng NMOR/mouse) and there was a two-fold increase when NO2 exposure was extended to 4 h. NMOR levels also increased in a time-dependent manner at 28.4 and 47.3 mg/m3 NO2 exposure levels, reaching a maximum of 450 and 725 ng NMOR/mouse, respectively, at 4 h. Oral administration of sodium ascorbate (50-250 mg), ammonium sulfamate (50-100 mg) or DL-alpha-tocopherol (67-167 mg) immediately after MOR or DMA, but prior to NO2 exposure, significantly inhibited both NMOR and NDMA biosynthesis, sulfamate being the most effective (greater than 90% NMOR and NDMA inhibition), followed by ascorbate (83-90% NMOR and 58-90% NDMA inhibition) and alpha-tocopherol (22-42% NMOR and 46-69% NDMA inhibition). Low levels of NDMA were found in untreated control mice (less than 13 ng/mouse) and in most samples of commercially obtained animal feed (10-15 micrograms/kg); NMOR, however, was not detectable or was detected in negligible amounts in these cases. Various control experiments indicated that most of the recovered nitrosamine resulted from in-vivo nitrosation in mice, with only up to 1-2% of NMOR and approximately 10% of NDMA yields being attributed to artefact formation, possibly during work-up of the mouse-powder samples.
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PMID:In-vivo nitrosation of amines in mice by inhaled nitrogen dioxide and inhibition of biosynthesis of N-nitrosamines. 653 19

Male CD-1 mice were exposed to approximately 20 ppm nitrogen dioxide (NO2) for 5-6 hours, to 1 g morpholine/kg body weight by gavage, or to both. Treatments were repeated daily for 5 consecutive days. N-nitrosomorpholine (NMOR) was found in whole carcasses (16-146 ng NMOR/mouse) in all animals that had been exposed to both NO2 and to morpholine, but NMOR was not found in tissues from animals that had been exposed to either chemical alone. Approximately one-third of the NMOR was found in the gastrointestinal tract, mainly in the stomach. The coadministration of 2 g sodium ascorbate/kg body weight or 1 g alpha-tocopheryl acetate/kg body weight had no effect on the amount of NMOR that was found in any tissue. Another possible product of the interaction of NO2 and morpholine, N-nitromorpholine, was not detected in any tissue. We concluded that the repeated, concurrent exposures of mice to NO2 by inhalation and to morpholine by gavage resulted in the in vivo formation of significant quantities of NMOR. The biological significance of the observation remains unknown.
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PMID:In vivo formation of N-nitrosomorpholine in CD-1 mice exposed by inhalation to nitrogen dioxide and by gavage to morpholine. 657 44


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