scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Selenium-mediated differential response of beta-glucosidase and beta-galactosidase of germinating Trigonella foenum-graecum.

01 Jan 1998-Biological Trace Element Research (Biol Trace Elem Res)-Vol. 64, Iss: 1, pp 247-258
TL;DR: The study reveals a differential response to Se among the β-galactosidase and β-glucosid enzyme of T. foenumgraecum with increase in the levels of β-GalactOSidase activity.
Abstract: Beta-glucosidase and beta-galactosidase activity profile tested in different seeds during 24 h germination revealed reasonably high levels of activity in Vigna radiata, Cicer arietinum, and Trigonella foenum-graecum. In all seeds tested, beta-galactosidase activity was, in general, higher than that of beta-glucosidase. T. foenum-graecum seedlings exhibited maximal total and specific activities for both the enzymes during 72 h germination. Se supplementation as Na2SeO3 up to 0.75 ppm was found to be beneficial to growth and revealed selective enhancement of beta-galactosidase activity by 40% at 0.5 ppm Se. The activities of both the enzymes drastically decreased at 1.0 ppm level of Se supplementation. On the contrary, addition of Na2SeO3 in vitro up to 1 ppm to the enzyme extracts did not influence these activities. Hydrolytic rates of beta-glucosidase in both control and Se-supplemented groups were enhanced by 20% with 0.05 M glycerol in the medium and 30% at 0.1 M glycerol. The rates were marginally higher in Se-supplemented seedlings than the controls, irrespective of added glycerol in the medium. In contrast, hydrolysis by beta-galactosidase showed a trend of decrease in Se-supplemented seedlings compared to the control, when glycerol was present in the medium. Addition of Se in vitro in the assay medium showed no difference in the hydrolytic rate by beta-galactosidase when compared to control, while the activity of beta-glucosidase declined by 50%. Se-grown seedlings showed an enhancement of transglucosidation rate by 40% in the presence of 0.1 M glycerol. The study reveals a differential response to Se among the beta-galactosidase and beta-glucosidase of T. foenum-graecum with increase in the levels of beta-galactosidase activity.
Citations
More filters
Journal ArticleDOI
TL;DR: In this article, the complementary role of selenium and sulfur specific chromatographic detection by HPLC with interfaced inductively coupled plasma mass spectrometry (ICP-MS) detection and by derivatization GC with interfacing atomic spectral emission was investigated.

124 citations

Journal ArticleDOI
TL;DR: In this article, the effect of se fertilization on sage (Salvia officinalis L.) under different salt stresses was examined and the results showed that Se treatments caused significant improvements in the dry weight (DW) of sage under salt stress.

12 citations

Journal ArticleDOI
TL;DR: In this article, the authors evaluated 11 concentrations of Se (0, 0.1; 0.5; 1, 5, 10, 20, 40, 80, 400, 800 mg.L-1) to determine the low and high (toxicity) critical levels to seed germination of cowpea (Vigna unguiculata).
Abstract: Selenium (Se) is considered a beneficial chemical element for plants, but in high concentrations it may present symptoms of toxicity. The present study aimed to evaluate 11 concentrations of Se (0; 0.1; 0.5; 1; 5; 10; 20; 40; 80; 400; 800 mg.L-1) to determine the low and high (toxicity) critical levels to seed germination of cowpea (Vigna unguiculata). In addition, alterations in the rate of photosynthetic pigments, lipid peroxidation and sugars during the initial growth development of seedlings were analysed. Seeds exposed to 800 mg.L-1 of Se showed a decrease of 20% of seed germination index compared to the control treatment. The decrease in seedling growth reflected in the increase of total sugars and sucrose concentration in both the shoot and root in response to exposure to Se concentration. There was a decrease in the concentration of leaf chlorophyll, carotenoids and pheophytin from seedlings exposed to high Se concentration. The rate of lipid peroxidation and the hydrogen peroxide concentration in the shoot was reduced up to the concentration of 1 mg.L-1 with subsequent increase in response to Se concentration applied. In the roots, the lipid peroxidation rate increased at concentrations higher than 80 mg.L-1. The highest oxidation rate of the cellular lipid membrane in response to Se occurred in the shoot, due to oxidation reactions in the chloroplast. Degradation of photosynthetic pigments and accumulation of total sugars and sucrose can be considered efficient biomarkers to indicate the toxicity of Se in cowpea seedlings and probably in other crops.

11 citations

Journal ArticleDOI
TL;DR: Observations provide evidence that Se accumulation in seeds is not likely to hamper breeding efforts for Se enrichment in B. oleracea at Se levels similar to this study.
Abstract: Breeding plants to be more efficient at micronutrient accumulation is a proposed strategy for fighting worldwide malnutrition of humans. Selection for increased selenium (Se) in Brassica oleracea L. is possible. However, when present at high levels, micronutrients such as Se can affect seed germination and subsequently hamper breeding efforts. The objectives of this study were: (1) to evaluate the accumulation of Se in seeds of B. oleracea; and (2) to determine effects that Se accumulation may have on seed germination. Plants of a rapid‐cycling B. oleracea population were grown in nutrient solutions with sodium selenate (Na2SeO4) concentrations up to 7 mg L−1 (2.93 mg Se L−1). Seeds and leaves were harvested from the selenized plants and analyzed for Se content using atomic absorption spectrophotometry. Germination percentage and rate were determined by sowing seeds in moistened towels, placing them in an incubator at 21°C, and observing radicle emergence. Selenium accumulated in the seeds, but a...

6 citations

Journal ArticleDOI
TL;DR: Although ethylene was required for dormancy breakage the compounds triggering the highest ethylene productions were not necessarily the same ones leading to the largest Ief(s), Hence it was concluded that the index is an overall integrating parameter, encompassing uptake of the compound, arrival to target cells and also post-ethylene biosynthesis effects.
Abstract: Selenium compounds break dormancy of seeds of Townsville stylo (Stylosanthes humilis) through the induction of ethylene production. This was supported by the fact that antiethylenic substances inhibited germination of Se-treated dormant seeds. Under these conditions germination was restored by ethylene-producing compounds. Efficacy of the compounds was monitored through an Efficiency Index (Ief) which takes into account not only the maximal germination but also the optimal concentration responsible for eliciting the process. The most efficient compounds were SeCl4, SeO2 and Na2SeO3 and the least efficient were selenourea, H2SeO4 and selenomethionine. Although ethylene was required for dormancy breakage the compounds triggering the highest ethylene productions were not necessarily the same ones leading to the largest Ief(s). Hence it was concluded that the index is an overall integrating parameter, encompassing uptake of the compound, arrival to target cells and also post-ethylene biosynthesis effects.

4 citations


Cites background from "Selenium-mediated differential resp..."

  • ...However, Se promoted a beneficial effect on germination of Vigna radiata seeds (Lalitha and Easwari, 1995) and, at low concentrations, favoured the germination of seeds of Trigonella foenum-graecum by increasing the activity of hydrolytic enzymes (Sreekala and Lalitha, 1998)....

    [...]

References
More filters
Journal Article
TL;DR: Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.

289,852 citations

Journal ArticleDOI

25,389 citations


"Selenium-mediated differential resp..." refers methods in this paper

  • ...1 M glycerol for 2 h and the nitrophenol moiety released was estimated as described above, while the level of reducing sugars in each case was also determined according to the method of Miller (21)....

    [...]

Journal ArticleDOI
09 Feb 1973-Science
TL;DR: When hemolyzates from erythrocytes of selenium-deficient rats were incubated in vitro in the presence of ascorbate or H2O2, added glutathione failed to protect the hemoglobin from oxidative damage.
Abstract: When hemolyzates from erythrocytes of selenium-deficient rats were incubated in vitro in the presence of ascorbate or H(2)O(2), added glutathione failed to protect the hemoglobin from oxidative damage. This occurred because the erythrocytes were practically devoid of glutathione-peroxidase activity. Extensively purified preparations of glutathione peroxidase contained a large part of the (75)Se of erythrocytes labeled in vivo. Many of the nutritional effects of selenium can be explained by its role in glutathione peroxidase.

6,893 citations

Journal ArticleDOI
TL;DR: With the steady increase in sequence and structural data, it is suggested that the enzyme classification system should perhaps be revised.
Abstract: The amino acid sequences of 301 glycosyl hydrolases and related enzymes have been compared. A total of 291 sequences corresponding to 39 EC entries could be classified into 35 families. Only ten sequences (less than 5% of the sample) could not be assigned to any family. With the sequences available for this analysis, 18 families were found to be monospecific (containing only one EC number) and 17 were found to be polyspecific (containing at least two EC numbers). Implications on the folding characteristics and mechanism of action of these enzymes and on the evolution of carbohydrate metabolism are discussed. With the steady increase in sequence and structural data, it is suggested that the enzyme classification system should perhaps be revised.

3,338 citations


"Selenium-mediated differential resp..." refers background in this paper

  • ...Glycosyl hydrolases with their ubiquitous distribution are also actively involved in the metabolism of complex carbohydrates during germination (15,16)....

    [...]

Journal ArticleDOI
TL;DR: A general picture of a minimal reaction mechanism, in good agreement with functional and structural data, is proposed and a reasonable model of glutathione binding is presented.
Abstract: The crystal structure of bovine erythrocyte glutathione peroxidase has been refined by a combined procedure of restrained crystallographic refinement and energy minimization at 0.20 nm resolution. The final R value at this resolution is 0.178. The r.m.s. deviation of main-chain atoms of the two independently refined monomers is 0.019 nm. The structure at 0.28 nm resolution, which has been determined by multiple isomorphous replacement, served as a starting model. The refined model allowed a detailed survey of the hydrogen-bonding pattern and of the subunit contact areas in the molecule. The model contains 165 solvent molecules per dimer, all taken as water molecules. The mobility of the structure was derived from the individual atomic temperature factors. The complete tetramer, including the active sites, seems to be rather rigid, except for narrow loops near to the N-terminal ends and some β turns exposed to solvent. The active centres of glutathione peroxidase are found in flat depressions on the molecular surface. The catalytically active selenocysteine residues could be located at the N-terminal ends of α helices forming βαβ substructures together with two adjacent parallel β strands. In the vicinity of the reactive group some aromatic amino acid side-chains could be localized. Especially Trp-148, which could be hydrogen bonded to SeCys-35, may play a functional role during catalysis. The results of substrate and inhibitor binding studies in solution and in the crystalline state could be interpreted by an apparent half-site reactivity of glutathione peroxidase. The enzyme seems to react in the sense of negative cooperativity with dimers being the functional units. Based on difference Fourier analyses of appropriate derivatives a reasonable model of glutathione binding is presented. Among the residues which could be of functional importance are Arg-40, Gln-130 and Arg-167, presumably forming salt bridges and a hydrogen bond to the glutathione molecule. In conclusion, a general picture of a minimal reaction mechanism, which is in good agreement with functional and structural data, is proposed. The main reaction of the catalytic cycle presumably shuttles between the selenolate and the selenenic acid state of SeCys-35.

629 citations