scholarly journals Characterization of dolichol and dolichyl phosphate phosphatase from soya beans (Glycine max)

1983 ◽  
Vol 213 (2) ◽  
pp. 513-518 ◽  
Author(s):  
K Ravi ◽  
J W Rip ◽  
K K Carroll
Keyword(s):  
Enzyme Activity ◽  
Glycine Max ◽  
Phosphatidic Acid ◽  
Phosphatase Activity ◽  
Lysophosphatidic Acid ◽  
Competitive Inhibition ◽  
High Yield ◽  
Dolichyl Phosphate ◽  
Ability To Act ◽  
Phosphorylated Compounds

A series of polyprenols, ranging in length from 15 to 22 isoprene units, has been isolated from soya beans (Glycine max) and purified by high-pressure liquid chromatography. N.m.r., i.r. and mass spectra of the compounds indicated that they are alpha-saturated polyprenols of the dolichol type. The amount present in dry seeds was about 9 mg/100 g, whereas dolichyl phosphate (Dol-P) was present only in trace amounts. Dol-P phosphatase activity was detected in the microsomal fraction of 5-day-old germinating soya-bean cotyledons. The Dol-P phosphatase activity was linear with respect to time and protein concentration and exhibited a broad pH optimum (pH 7-9). Triton X-100 was necessary for significant enzyme activity. Enzyme activity was slightly enhanced by EDTA, whereas dithiothreitol was without effect. An apparent Km of 5 microM was determined for Dol-P. Bivalent metal ions were not required for enzyme activity. A number of phosphorylated compounds tested as enzyme substrates (including a number of nucleoside phosphates, glucose 6-phosphate, sodium β 1 leads to 4Glc. Because of the ease of purification of the enzyme and high yield in the absence of contaminating glycosidases and proteinases, Bacteroides fragilis is a valuable source of endo-beta-galactosidase for the structural analysis of carbohydrate chains. -glycerophosphate and Na4P2O7) did not compete with [1-3H]Dol-P as substrate. A number of phospholipids were also tested for their ability to act as Dol-P phosphatase substrates. At 1 mM concentration, phosphatidylcholine, phosphatidylethanolamine, phosphatidic acid and lysophosphatidic acid each inhibited enzymic activity. However, at 0.1 mM concentration, phosphatidylcholine and phosphatidylethanolamine were slightly stimulatory, whereas phosphatidic acid and lysophosphatidic acid were still inhibitory. Phosphatidic acid showed competitive inhibition.

scholarly journals Comparison of glycerolipid biosynthesis in non-green plastids from sycamore (Acer pseudoplatanus) cells and cauliflower (Brassica oleracea) buds

1989 ◽  
Vol 259 (3) ◽  
pp. 775-783 ◽  
Author(s):  
C Alban ◽  
J Joyard ◽  
R Douce
Keyword(s):  
Fatty Acids ◽  
Phosphatidic Acid ◽  
Brassica Oleracea ◽  
Phosphatase Activity ◽  
Lysophosphatidic Acid ◽  
Acyl Carrier Protein ◽  
Acer Pseudoplatanus ◽  
Envelope Membrane ◽  
Phosphatidate Phosphatase ◽  
Envelope Membranes

The availability of methods to fractionate non-green plastids and to prepare their limiting envelope membranes [Alban, Joyard & Douce (1988) Plant Physiol. 88, 709-717] allowed a detailed analysis of the biosynthesis of lysophosphatidic acid, phosphatidic acid, diacylglycerol and monogalactosyl-diacylglycerol (MGDG) in two different types of non-green starch-containing plastids: plastids isolated from cauliflower buds and amyloplasts isolated from sycamore cells. An enzyme [acyl-ACP (acyl carrier protein):sn-glycerol 3-phosphate acyltransferase) recovered in the soluble fraction of non-green plastids transfers oleic acid from oleoyl-ACP to the sn-1 position of sn-glycerol 3-phosphate to form lysophosphatidic acid. Then a membrane-bound enzyme (acyl-ACP:monoacyl-sn-glycerol 3-phosphate acyltransferase), localized in the envelope membrane, catalyses the acylation of the available sn-2 position of 1-oleoyl-sn-glycerol 3-phosphate by palmitic acid from palmitoyl-ACP. Therefore both the soluble phase and the envelope membranes are necessary for acylation of sn-glycerol 3-phosphate. The major difference between cauliflower (Brassica oleracea) and sycamore (Acer pseudoplatanus) membranes is the very low level of phosphatidate phosphatase activity in sycamore envelope membrane. Therefore, very little diacylglycerol is available for MGDG synthesis in sycamore, compared with cauliflower. These findings are consistent with the similarities and differences described in lipid metabolism of mature chloroplasts from ‘C18:3’ and ‘C16:3’ plants (those with MGDG containing C18:3 and C16:3 fatty acids). Sycamore contains only C18 fatty acids in MGDG, and the envelope membranes from sycamore amyloplasts have a low phosphatidate phosphatase activity and therefore the enzymes of the Kornberg-Pricer pathway have a low efficiency of incorporation of sn-glycerol 3-phosphate into MGDG. By contrast, cauliflower contains MGDG with C16:3 fatty acid, and the incorporation of sn-glycerol 3-phosphate into MGDG by the enzymes associated with envelope membranes is not limited by the phosphatidate phosphatase. These results demonstrate that: (1) non-green plastids employ the same biosynthetic pathway as that previously established for chloroplasts (the formation of glycerolipids is a general property of all plastids, chloroplasts as well as non-green plastids), (2) the envelope membranes are the major structure responsible for the biosynthesis of phosphatidic acid, diacylglycerol and MGDG, and (3) the enzymes of the envelope Kornberg-Pricer pathway have the same properties in non-green starch-containing plastids as in mature chloroplasts from C16:3 and C18:3 plants.

Enzymatic dephosphorylation of retinyl monophosphate by rat liver

1986 ◽  
Vol 64 (9) ◽  
pp. 864-868
Author(s):  
Providencia Rodríguez ◽  
Olga Bello
Keyword(s):  
Phosphatase Activity ◽  
Rat Liver ◽  
Reaction Rate ◽  
Tween 80 ◽  
Maximum Reaction Rate ◽  
Dolichyl Phosphate ◽  
Maximum Reaction ◽  
Phosphorylated Compounds ◽  
Ph Range ◽  
Triton X

Rat liver has been shown to contain an enzyme that catalyzes the dephosphorylation of retinyl monophosphate. This activity was extracted with 0.1 M Tris buffer (pH 7.5). Maximum reaction rate was observed at a pH range of 7.0–7.5. It did not require metal ions for activity and was sensitive to fluoride ion. The retinyl monophosphate phosphatase activity was proportional to time and protein and substrate concentration. Triton X-100 (range of 0.05–0.10%) increased the activity 100%, whereas other detergents (Tween 80, cholate, and deoxycholate) did not activate the enzyme. A number of phosphorylated compounds tested as inhibitors of retinyl monophosphatase activity, such as glucose 6-phosphate (20 mM), glycerophosphate (20 mM), phosphatidic acid (8 mM), and dolichyl phosphate (3 mM), did not compete with retinyl monophosphate as substrate. However, at 20 mM concentration, ATP, ADP, 5′-AMP, and pyrophosphate were inhibitors of the enzyme. It is not possible at present to give further details about the specificity of the phosphatase activity. The enzyme described could play a regulatory role in retinol-mediated glycosylations, by altering the endogenous level of retinyl monophosphate.

scholarly journals Increase in alkaline phosphatase activity in calvaria cells cultured with diphosphonates

1979 ◽  
Vol 183 (1) ◽  
pp. 73-81 ◽  
Author(s):  
R Felix ◽  
H Fleisch
Keyword(s):  
Alkaline Phosphatase ◽  
Protein Synthesis ◽  
Enzyme Activity ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Heat Inactivation ◽  
High Concentration ◽  
Control Value ◽  
Km Value ◽  
Inhibitor Of Protein Synthesis

1. Dichloromethanediphosphonate and to a lesser degree 1-hydroxyethane-1,1-diphosphonate, two compounds characterized by a P-C-P bond, increased the alkaline phosphatase activity of cultured rat calvaria cells up to 30 times in a dose-dependent fashion. 2. Both diphosphonates also slightly inhibited the protein synthesis in these cells. 3. Thymidine, an inhibitor of cell division, did not inhibit the induction of the enzyme, indicating that the increase in enzyme activity was not due to the formation of a specific population of cells with high alkaline phosphatase activity. 4. The effect on alkaline phosphatase was suppressed by the addition of cycloheximide, an inhibitor of protein synthesis. 5. After subculturing the stimulated cells in medium without diphosphonates, the enzyme activity fell almost to the control value. 6. Bovine parathyrin diminished the enzyme activity of the control cells and the cells treated with dichloromethanediphosphonate; however, at high concentration the effect of parathyrin was greater on the diphosphonate-treated cells than on the control cells. 7. The electrophoretic behaviour, heat inactivation, inhibition by bromotetramisole or by phenylalanine, and the Km value of the induced enzyme were identical with that of the control enzyme.

Acid phosphatase, alkaline phosphatase, and nitrate reductase activity of selected ectomycorrhizal fungi

1989 ◽  
Vol 67 (3) ◽  
pp. 750-753 ◽  
Author(s):  
Iwan Ho
Keyword(s):  
Alkaline Phosphatase ◽  
Enzyme Activity ◽  
Acid Phosphatase ◽  
Nitrate Reductase ◽  
Phosphatase Activity ◽  
Ectomycorrhizal Fungi ◽  
Acid Phosphatase Activity ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Phosphatase Alkaline

Seventeen isolates, encompassing five genera and eight species of ectomycorrhizal fungi, were compared for acid phosphatase, alkaline phosphatase, and nitrate reductase activity. Isolates within species differed in enzyme activity and isozyme patterns by host specificity and site (as exemplified by the genus Suillus). Host and site may have affected phosphatase enzyme activity. Generally, the Douglas-fir associates, which dominate in mesic sites, have higher acid phosphatase activity than pine associates, which mostly occupy xeric sites; however, pine associates from mesic sites also have higher acid phosphatase activity (e.g., S. tomentosus). In four isolates of Amanita muscaria, the effect of site was also apparent. Two of them, which have significantly higher acid phosphatase activity than the others, were isolated from mesic sites. The isozyme pattern of the genus Suillus appeared to be separated by host groups. Other isolates with only one species also differed more or less by host groups. They shared at least one band within host groups, except for the two isolates of Paxillus involutus from different hosts. The P. involutus S-403 isolated from an orchard showed much higher nitrate reductase activity than all other isolates. No apparent differences in nitrate reductase activity were found between the other isolates.

scholarly journals Aspectos Bionômicos de Spodoptera eridania (Cramer): Uma Praga em Expansão na Cultura da Soja na Região do Cerrado Brasileiro

2014 ◽  
Vol 7 (2) ◽  
pp. 75-80 ◽  
Author(s):  
Bruno Henrique Sardinha de Souza ◽  
Eduardo Neves Costa ◽  
Anderson Gonçalves da Silva ◽  
Arlindo Leal Boiça Júnior
Keyword(s):  
International Trade ◽  
Glycine Max ◽  
Insect Pests ◽  
High Yield ◽  
Spodoptera Eridania ◽  
Soybean Crop ◽  
Glycine Max L ◽  
Midwest Region ◽  
Soybean Plants ◽  
Economical Losses

A soja, Glycine max (L.) Merril, é uma das culturas de maior importância econômica para o Brasil, considerada uma commodity nacional devido à sua alta produtividade e participação nas exportações no mercado internacional. Dentre os insetos-pragas que causam danos para essa cultura, nos últimos anos agrícolas têm merecido destaque as lagartas de Spodoptera eridania (Cramer), as quais podem se alimentar tanto de folhas quanto das vagens das plantas de soja, causando prejuízos econômicos para os sojicultores, principalmente nas áreas do Cerrado localizadas na região Centro-Oeste do país. O objetivo da presente revisão é disponibilizar informações sobre os aspectos bionômicos de S. eridania, a fim de dar subsídios para futuras pesquisas sobre o manejo dessa praga.Bionomic Aspects of Spodoptera eridania (Cramer): A Pest in Expansion on Soybean Crop in the Region of Brazilian CerradoAbstract. Soybean, Glycine max (L.) Merril, represents one of the major economically important crops to Brazil, and is considered a national commodity because of its high yield and participation in international trade exportations. Among the insect pests that cause damage to this crop, Spodoptera eridania (Cramer) larvae highlighted in the last agricultural seasons by feeding on leaves and pods of soybean plants, and hence causing economical losses to soybean growers, especially in the Cerrado areas located in the Midwest region of the country. We aimed with this review to provide information about bionomical aspects of S. eridania in order to give subsides for further researches on the management of this pest.

The improvement of lipase secretion and stability by addition of inert compounds into Acinetobacter calcoaceticus cultures

2002 ◽  
Vol 48 (12) ◽  
pp. 1056-1061 ◽  
Author(s):  
Daniela A Martinez ◽  
B Clara Nudel
Keyword(s):  
Enzyme Activity ◽  
Gum Arabic ◽  
Acinetobacter Calcoaceticus ◽  
Glass Beads ◽  
High Yield ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene ◽  
Cell Fractions ◽  
Triton X ◽  
Effective Additive

Acinetobacter calcoaceticus BD413 produces variable amounts of an exocellular lipase that becomes rapidly inactivated upon secretion. To achieve high yield and protect the enzyme, we assayed the addition of several inert compounds to cell-free supernatants, cell fractions, and whole cultures. Glass beads, poly(ethylene glycol) 600, Triton X-100, saccharose, gum arabic, and β-cyclodextrin were among the compounds tested. β-Cyclodextrin and gum arabic (and saccharose to a lesser extent) were effective enzyme stabilizers in cell-free supernatants, while gum arabic, glass beads, and Triton X-100 improved lipase secretion from cells, and, therefore, total lipase yield (30–50%, according to the additive). In whole cultures, β-cyclodextrin was the most effective additive, particularly in combination with glass beads or gum arabic. Indeed, cultures containing β-cyclodextrin plus gum arabic were able to maintain 95% (±1.5%) of the initial lipase activity for more than 16 h, while control cultures with no additives maintained only 10% (±4%) of the enzyme activity after the same period. In conclusion, the addition of inert compounds in cultures may be considered a useful approach for achieving increased yield and lipase stabilization, amenable for downstream processing.Key words: Acinetobacter calcoaceticus, lipase, secretion, stabilization, inert additives.

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