Partial purification of galactinol synthase from leaves of Cucurbita pepo

1982 ◽  
Vol 60 (7) ◽  
pp. 1054-1059 ◽  
Author(s):  
John A. Webb
Keyword(s):  
Cucurbita Pepo ◽  
Partial Purification ◽  
Galactinol Synthase ◽  
Inositol 1 ◽  
Mature Leaves ◽  
Galactosyl Transferase ◽  
Naturally Occurring ◽  
High Concentrations ◽  
Uridine Nucleotides

An enzyme synthesizing galactinol, UDP-D-galactose:myo-inositol-1-α-D-galactosyl transferase (galactinol synthase), has been isolated and partially purified from mature leaves of Cucurbita pepo. The enzyme showed optimal activity between pH 7.5 and 8.0 and required Mn2+ and the presence throughout isolation, storage, and assay of a sulfhydryl protectant (β-mercaptoethanol). EDTA was completely inhibitory. From a range of metal ions only Mg2+ partially replaced Mn2+, while Co2+, Zn2+, Cu2+, and Ni2+ were inhibitory. The uridine nucleotides and UDP-glucose were from 40 to 80% inhibitory and probably constitute part of the in vivo control system. High concentrations of galactose, melibiose, and xylose were partially inhibitory. The enzyme appeared highly specific for myo-inositol and showed no ability for galactosyl transfer to any other naturally occurring sugar or sugar alcohol. Some reactivity was obtained with the isomeric scyllo-inositol but the product was not identified. A range of other sugar nucleotides were unreactive.

Phytoestrogens

1998 ◽  
Vol 4 (1) ◽  
pp. 18-23 ◽  
Author(s):  
Rachel Mackey ◽  
John Eden
Keyword(s):  
Epidemiological Data ◽  
Asian Populations ◽  
Colon Cancers ◽  
Naturally Occurring ◽  
Urinary Levels ◽  
High Dietary Intake ◽  
High Concentrations ◽  
Relative Potencies

Phytoestrogens are defined as naturally occurring compounds found in plants that are structurally and functionally similar to 17-ß oestradiol or that produce oestrogenic effects. They are diphenolic in structure and are most commonly found in cereals, legumes and grasses. There have been numerous classes identified, the mostly highly investigated being isoflavones and lignans. Isoflavones are attenuated oestrogens. They behave both in vivo and in vitro as agonists and antagonists. Genistein and daidzein are found in high concentrations in soy beans and soy products. Their relative potencies as compared to oestradiol are low but they exhibit equivalent levels of bioactivity when tested in high concentrations. Lignans are found in oilseeds, cereals and berries. The main urinary lignans are enterolactone and enterodiol. Most phytoestrogens are modified by gut flora from glycoside precursors to a compound with oestrogenic properties. A high dietary intake of phytoestrogens was first noted to be associated with decreased incidences of certain diseases. This epidemiological data was obtained primarily from studying Asian populations. Soy consumption is highest in Japan, where urinary levels of phytoestrogen metabolites are extremely high and there are lower rates of so-called ‘Western’ diseases, including breast, endometrial, colon cancers as well as atherosclerotic disease. Research to date has focused on the antiproliferative potential of phytoestrogens, primarily genistein both in vitro and in vivo. Their role in the relief of menopausal symptoms, their hypocholesterolaemic effects and bone resorption protection have been investigated to some extent with promising results. A brief overview of the background of, and the research into, phytoestrogens will be provided in this article.

scholarly journals The activity and kinetic properties of mevalonate kinase in superovulated rat ovary

1970 ◽  
Vol 120 (1) ◽  
pp. 145-150 ◽  
Author(s):  
A. P. F. Flint
Keyword(s):  
Luteinizing Hormone ◽  
Total Activity ◽  
Partial Purification ◽  
Kinetic Properties ◽  
Mevalonate Kinase ◽  
Farnesyl Pyrophosphate ◽  
Rat Ovary ◽  
High Concentrations ◽  
Geranyl Pyrophosphate

Methods are described for the assay and partial purification of mevalonate kinase from superovulated rat ovary. The total activity of mevalonate kinase in superovulated rat ovary was 1.6±0.14units/g wet wt.; it was unchanged by the administration of luteinizing hormone in vivo. The Km of a partially purified preparation of mevalonate kinase for dl-Mevalonate was 3.6±0.5μm; its Km for MgATP2− was 120±7.7μm. The enzyme was inhibited by geranyl pyrophosphate and farnesyl pyrophosphate, but not by isopentenyl pyrophosphate or 3,3′-dimethylallyl pyrophosphate. dl-mevalonate 5-phosphate inhibited at high concentrations. With both geranyl pyrophosphate and farnesyl pyrophosphate the inhibition was competitive with respect to MgATP2−. The Ki for inhibition by geranyl pyrophosphate was 1.3±0.2μm; the Ki for inhibition by farnesyl pyrophosphate was 1.0±0.3μm. These findings are discussed with reference to the control by luteinizing hormone of steroidogenesis from acetate.

scholarly journals Partial purification and regulatory properties of phosphofructokinase from Aspergillus niger

1983 ◽  
Vol 209 (3) ◽  
pp. 669-676 ◽  
Author(s):  
A Habison ◽  
C P Kubicek ◽  
M Röhr
Keyword(s):  
Citric Acid ◽  
Aspergillus Niger ◽  
Kinetic Studies ◽  
Maximal Activity ◽  
Distinct Species ◽  
Hill Coefficient ◽  
Partial Purification ◽  
Maximal Velocity ◽  
High Concentrations

Phosphofructokinase (EC 2.7.1.11) from a citric acid-producing strain of Aspergillus niger was partially purified by the application of affinity chromatography on Blue Dextran-Sepharose and the use of fructose 6-phosphate and glycerol as stabilizers in the working buffer. The resulting preparation was still impure, but free of enzyme activities interfering with kinetic investigations. Kinetic studies showed that the enzyme exhibits high co-operativity with fructose 6-phosphate, but shows Michaelis-Menten kinetics with ATP, which inhibits at concentrations higher than those for maximal activity. Citrate and phosphoenolpyruvate inhibit the enzyme; citrate increases the substrate (fructose 6-phosphate) concentration for half-maximal velocity, [S]0.5, and the Hill coefficient, h. The inhibition by citrate is counteracted by NH4+, AMP and phosphate. Among univalent cations tested only NH4+ activates by decreasing the [S]0.5 for fructose 6-phosphate and h, but has no effect on Vmax. AMP and ADP activate at low and inhibit at high concentrations of fructose 6-phosphate, thereby decreasing the [S]0.5 for fructose 6-phosphate. Phosphate has no effect in the absence of citrate. The results indicate that phosphofructokinase from A. niger is a distinct species of this enzyme, with some properties similar to those of the yeast enzyme and in some other properties resembling the mammalian enzyme. The results of determinations of activity at substrate and effector concentrations resembling the conditions that occur in vivo support the hypothesis that the apparent insensitivity of the enzyme to citrate during the accumulation of citric acid in the fungus is due to counteraction of citrate inhibition by NH4+.

INVESTIGATIONS INTO THE POSSIBLE EFFECTS OF NATURALLY OCCURRING STEROIDS ON BIOSYNTHESIS OF 16-ANDROSTENES AND ANDROGENS IN MICROSOMES OF BOAR TESTIS

1981 ◽  
Vol 88 (3) ◽  
pp. 409-418 ◽  
Author(s):  
G. M. COOKE ◽  
D. B. GOWER
Keyword(s):  
Microsomal Fraction ◽  
Hydroxysteroid Dehydrogenase ◽  
Side Chain ◽  
Biosynthetic Pathways ◽  
Michaelis Constant ◽  
Ph Optimum ◽  
Naturally Occurring ◽  
Chain Cleavage ◽  
High Concentrations

The possible interactions between naturally occurring steroids and three enzymes of the biosynthetic pathways of 16-androstenes and androgens in the boar testis were investigated. High concentrations (1 mmol/l) of several steroids reduced the production of 5,16-androstadien-3β-ol when a microsomal fraction of boar testis was incubated with pregnenolone at pH 7·0 (the pH optimum of this reaction was found to be 6·6). When some of these inhibitors were investigated in more detail using Lineweaver–Burk analyses, the apparent inhibition constants, Ki, increased in value with increasing concentrations of inhibitors. When testosterone was added to 5,16-androstadien-3β-ol synthetase assays, the apparent Ki for 0·1 μmol testosterone/l was 0·165 μmol/l whereas those for 1·0, 10·0 and 100·0 μmol testosterone/l were 1·65, 16·5 and 48·7 μmol/l respectively. The apparent Michaelis constant, Km, of the reaction was 0·6 μmol/l. Similar results were obtained when oestrone, 17α-hydroxyprogesterone and 4,16-androstadien-3-one were added as effectors. At physiological concentrations, these steroids would not affect the biosynthesis of 5,16-androstadien-3 β-ol in vivo. Similarly, both 5α-androst-16-en-3β-ol, quantitatively the most important 16-androstene in the boar testis and 5,16-androstadien-3β-ol were examined for their effects on the 17α-hydroxy-C21 -steroid, C-17,20 lyase (C-17,20 lyase) and 17β-hydroxysteroid dehydrogenase (17β-OHSDH) enzymes of androgen biosynthesis. Neither of these enzymes was affected by the 16-androstene steroids even at concentrations of 100 μmol/l, and the apparent Km values were 3·3 and 26·0 μmol/l for C-17,20 lyase and 17β-OHSDH respectively. This lack of interaction between these pathways implies that the high levels of 16-androstene steroids produced by the testis will not interfere with androgen production, and also that the two side-chain cleavage steps from C21 precursors to C19 steroids are catalysed by independent systems.

Erratum: Partial purification of galactinol synthase from leaves of Cucurbita pepo

1983 ◽  
Vol 61 (1) ◽  
pp. 376-376 ◽  
Author(s):  
John A. Webb
Keyword(s):  
Cucurbita Pepo ◽  
Partial Purification ◽  
Galactinol Synthase

scholarly journals Curcumin, Gut Microbiota, and Neuroprotection

Nutrients ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2426 ◽  
Author(s):  
Di Meo ◽  
Margarucci ◽  
Galderisi ◽  
Crispi ◽  
Peluso
Keyword(s):  
Neurological Diseases ◽  
Aqueous Solubility ◽  
Brain Health ◽  
Active Metabolites ◽  
Pharmacological Activities ◽  
Naturally Occurring ◽  
The Central Nervous System ◽  
High Concentrations

Curcumin, a nontoxic, naturally occurring polyphenol, has been recently proposed for the management of neurodegenerative and neurological diseases. However, a discrepancy exists between the well-documented pharmacological activities that curcumin seems to possess in vivo and its poor aqueous solubility, bioavailability, and pharmacokinetic profiles that should limit any therapeutic effect. Thus, it is possible that curcumin could exert direct regulative effects primarily in the gastrointestinal tract, where high concentrations of curcumin are present after oral administration. Indeed, a new working hypothesis that could explain the neuroprotective role of curcumin despite its limited availability is that curcumin acts indirectly on the central nervous system by influencing the “microbiota–gut–brain axis”, a complex bidirectional system in which the microbiome and its composition represent a factor which preserves and determines brain “health”. Interestingly, curcumin and its metabolites might provide benefit by restoring dysbiosis of gut microbiome. Conversely, curcumin is subject to bacterial enzymatic modifications, forming pharmacologically more active metabolites than curcumin. These mutual interactions allow to keep proper individual physiologic functions and play a key role in neuroprotection.

scholarly journals Hercynine, Ergothioneine and Redox State in Stallion’s Seminal Plasma

Antioxidants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 855
Author(s):  
Salvatore Sotgia ◽  
Andrea Taras ◽  
Angelo Zinellu ◽  
Raffaele Cherchi ◽  
Arduino A Mangoni ◽  
...  
Keyword(s):  
Seminal Plasma ◽  
Reactive Nitrogen Species ◽  
Redox State ◽  
Semen Quality ◽  
Biological Fluid ◽  
Oxygen Species ◽  
Naturally Occurring ◽  
High Concentrations ◽  
Regeneration Processes

The dependence of a stallion’s spermatozoa on oxidative phosphorylation for energy requirements results in an unconventional relationship between reactive oxygen species (ROS) production and fertility. In such a scenario, antioxidant activity must be finely controlled and not affect the essential functions of ROS. Some in vivo evidence suggests that the naturally occurring antioxidant ergothioneine (ERT) interferes with the critical roles of ROS/reactive nitrogen species (RNS) in pro-oxidant states but not in healthy tissues. The measurement of ERT in seminal plasma collected from 14 stallions (five Anglo-Arab, five Sella Italiano and four Thoroughbreds of which three are Arabian and one English) aged 16 ± 6 years (range 6–25 years) confirms that ERT is present at high concentrations in this biological fluid, between 16.80 and 971.48 µmol/L. Although the presence of high ERT concentrations in the seminal plasma of a stallion has long been known, its exact biological role is uncertain. This might be due to the peculiar antioxidant cycle of ERT, specifically its rapid recovery, which potentially masks concentration fluctuations and, therefore, the extent of its physiological effects. The measurement of the ERT precursor and redox metabolite hercynine (ERY) may overcome such issues, as ERY does not undergo regeneration processes. ERY was detectable and measurable in the seminal plasma of all stallions at a median concentration of 7.50 (IQR 15.26) nmol/L. The analysis of the association between the ERT and ERY, as well as with other established antioxidants such as glutathione and cysteine, suggests that ERT may play a major role in the antioxidant machinery of seminal plasma, and that ERY might serve as a new combined marker of oxidative stress and semen quality.

scholarly journals Partial Purification and Properties of an Alkaline α-Galactosidase from Mature Leaves of Cucurbita pepo

1983 ◽  
Vol 71 (3) ◽  
pp. 662-668 ◽  
Author(s):  
Pierre-Richard Gaudreault ◽  
John A. Webb
Keyword(s):  
Cucurbita Pepo ◽  
Partial Purification ◽  
Mature Leaves ◽  
Purification And Properties

Hair cell changes after cationic stimulation of corti's organ

1989 ◽  
Vol 47 ◽  
pp. 798-799
Author(s):  
Cesar D. Fermin ◽  
Hans-Peter Zenner
Keyword(s):  
Organ Of Corti ◽  
Cross Sectional ◽  
Surface Areas ◽  
High K ◽  
Anatomical Arrangement ◽  
Cell Cytosol ◽  
High Concentrations ◽  
K Concentration ◽  
Cell Changes

Contraction of outer and inner hair cells (OHC&IHC) in the Organ of Corti (OC) of the inner ear is necessary for sound transduction. Getting at HC in vivo preparations is difficult. Thus, isolated HCs have been used to study OHC properties. Even though viability has been shown in isolated (iOHC) preparations by good responses to current and cationic stimulation, the contribution of adjoining cells can not be explained with iOHC preparations. This study was undertaken to examine changes in the OHC after expossure of the OHC to high concentrations of potassium (K) and sodium (Na), by carefully immersing the OC in either artifical endolymph or perilymph. After K and Na exposure, OCs were fixed with 3% glutaraldehyde, post-fixed in osmium, separated into base, middle and apex and embedded in Araldite™. One μm thick sections were prepared for analysis with the light and E.M. Cross sectional areas were measured with Bioquant™ software.Potassium and sodium both cause isolated guinea pig OHC to contract. In vivo high K concentration may cause uncontrolled and sustained contractions that could contribute to Meniere's disease. The behavior of OHC in the vivo setting might be very different from that of iOHC. We show here changes of the cell cytosol and cisterns caused by K and Na to OHC in situs. The table below shows results from cross sectional area measurements of OHC from OC that were exposed to either K or Na. As one would expect, from the anatomical arrangement of the OC, OHC#l that are supported by rigid tissue would probably be displaced (move) less than those OHC located away from the pillar. Surprisingly, cells in the middle turn of the cochlea changed their surface areas more than those at either end of the cochlea. Moreover, changes in surface area do not seem to differ between K and Na treated OCs.

STEROID METABOLISM IN THE PERFUSED HUMAN PLACENTA

1978 ◽  
Vol 87 (1) ◽  
pp. 181-191 ◽  
Author(s):  
Alfred S. Wolf ◽  
Klaus A. Musch ◽  
Werner Speidel ◽  
Jürgen R. Strecker ◽  
Christian Lauritzen
Keyword(s):  
Venous Blood ◽  
Placental Lactogen ◽  
Dehydroepiandrosterone Sulphate ◽  
Metabolic Capacity ◽  
Loading Test ◽  
Lower Range ◽  
Group I ◽  
High Concentrations ◽  
Steroid Precursor

ABSTRACT A new model for the perfusion of human term-placentas has been developed for studies on the placental biogenesis of C-18 and C-19 steroids. For viability criteria, the glucose- and oxygen-consumption, regional perfusion control by dye-infusions or scanning after injection of 99Tc-labelled macroparticles, and the histological qualification were chosen. The recycled perfusate was investigated for the steroids oestrone (Oe1), oestradiol-17β (Oe2), oestriol (Oe3), 4-androstene-3,17-dione (A), testosterone (T), and human placental lactogen (HPL) by radioimmunoassay in controls and perfusions with the foetal steroid precursor dehydroepiandrosterone sulphate (DHA-S). In control perfusions, steroid hormones were found in constant ratios (Oe1:Oe2:Oe3:T:A = 30:1.5:100:0.35:1). Following the administration of 10 mg DHA-S for testing the metabolic capacity of the organ, high concentrations of Oe1 (90–720 ng/ml = 250–3970 % as compared to 100% pre-injection values) were found, shortly preceded by a rapid increase of A (66–1000 ng/ml = 100–16 000 %). A typical surge of T (5.3–147 ng/ml = 265–4640 %) preceded the normally slower increment of Oe2 (22–220 ng/ml = 1570–4330 %). The concentrations of Oe3 and HPL remained nearly unchanged. From different steroid patterns after DHA-S-load, two distinct responses of term-placentas could be differentiated: Group I (n=12) showed high concentrations of Oe1 (3200 ± 940 %), a small increase of T (1020 ± 500%), as well as low and delayed values of Oe2 (1660 ± 450%). In Group II (n = 5), values were high for T (3160 ± 1020%) and Oe2 (3300 ± 1110%), whereas Oe1 was found in a lower range (508 ± 302%). In contrast to in vivo findings in maternal venous blood after DHS-S injection to the mother, oestrone was found in perfusions as the main oestrogen fraction from DHA-S. Thus, the analysis of such metabolic differences might be of help in the interpretation of complex results from the DHA-S-loading test.

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