scholarly journals Solubilization of β-glucan synthases from the membranes of cultured ryegrass endosperm cells

1982 ◽  
Vol 203 (3) ◽  
pp. 629-636 ◽  
Author(s):  
R J Henry ◽  
B A Stone
Keyword(s):  
Lolium Multiflorum ◽  
Partial Purification ◽  
Beta Glucan ◽  
Glucan Synthase ◽  
Steryl Glucosides ◽  
Octyl Glucoside ◽  
Beta Glucans ◽  
Membrane Bound ◽  
Glucan Synthesis

beta-Glucan synthases were solubilized by treating membrane preparations from suspension-cultured ryegrass (lolium multiflorum) endosperm cells with detergents. Of the seven detergents tested only digitonin and octyl glucoside dissociated active synthases from the membranes. The digitonin-solubilized enzymes produced 1,4-beta-glucans and 1,3:1,4-beta-glucans, whereas the digitonin-insoluble enzymes produced, in addition, 1,3-beta-glucans. Chromatography of the digitonin-solubilized beta-glucan synthases on DEAE-Sepharose resulted in their partial purification. The octyl glucoside-solubilized enzymes produced more 1,3-beta-glucans than did the membrane-bound preparations. These results suggest that the 1,3-beta-glucan synthase is a separate enzyme and is not involved in 1,3:1,4-beta-glucan synthesis. Digitonin not only dissociated synthases from the membranes, but also stimulated synthase activity. This effect may be related to the inhibition by digitonin of glucosyl transfer from UDP-glucose to form steryl glucosides.

scholarly journals Localization of β-glucan synthases on the membranes of cultured Lolium multiflorum (ryegrass) endosperm cells

1983 ◽  
Vol 209 (3) ◽  
pp. 627-633 ◽  
Author(s):  
R J Henry ◽  
A Schibeci ◽  
B A Stone
Keyword(s):  
Density Gradient ◽  
Plasma Membranes ◽  
Lolium Multiflorum ◽  
Sucrose Density Gradient ◽  
Italian Ryegrass ◽  
Beta Glucan ◽  
Glucan Synthase ◽  
Intracellular Membranes

The distribution of beta-glucan synthases between plasma membranes and intracellular membranes of suspension-cultured Italian-ryegrass (Lolium multiflorum Lam.) endosperm cells was examined. Highly purified plasma membranes prepared from protoplasts were only slightly enriched in beta-glucan synthases assayed at 10 microM- and 1 mM-UDP-glucose. Most beta-glucan synthase was associated with intracellular membranes. These membranes were fractionated on a linear sucrose density gradient and were resolved into different membrane fractions containing beta-glucan synthases. Beta-Glucan synthases assayed at 10 microM-UDP-glucose were found in a fraction banding at a density of 1.11 g . cm-3, but most of the beta-glucan synthase assayed at 1 mM-DDP-glucose was at a density of 1.04 g . cm-3.

Interaction of sulfhydryl reactive reagents with components involved in (1,3)-β-glucan synthesis from Candida albicans

1995 ◽  
Vol 41 (8) ◽  
pp. 692-698 ◽  
Author(s):  
David J. Frost ◽  
Kim Brandt ◽  
Tim Kaufmann ◽  
Robert Goldman
Keyword(s):  
Candida Albicans ◽  
Binding Protein ◽  
Sulfhydryl Reagents ◽  
Gtp Binding Protein ◽  
Rapid Separation ◽  
Glucan Synthase ◽  
Gtp Binding ◽  
Catalytic Active Site ◽  
Membrane Bound ◽  
Glucan Synthesis

Glucan synthesis was sensitive to several sulfhydryl reacting compounds: mercurials, reversible disulfides, and an alkylating sulfhydryl reagent (IC50 3–45 μM). Thiol groups associated with glucan synthesis were hydrophilic in nature, since both hydrophilic and hydrophobic reagents were active. Glucan synthase complex consists of at least two components: a peripheral GTP-binding protein that can be solubilized with detergents (supernatant) and the catalytic membrane-bound component (pellet). A rapid separation technique was developed to study sulfhydryl interactions with the complex. The GTP-binding protein was solubilized with 0.6% 3-((3-cholamidopropyl)dimethylammonio)-1-propane sulfonate from isolated microsomes of Candida albicans cells grown at either 10 or 30 °C. The residual membranous fraction contained the core catalytic moiety of glucan synthase. Both fractions were devoid of glucan synthase activity until they were reconstituted by mixing the two fractions together. In reconstitution experiments, the pellet lost almost 50% activity when preincubated with 2.5 μM N-ethylmaleimide and combined with an untreated supernatant whereas only 10% activity was lost when the supernatant was treated with N-ethylmaleimide. The catalytic active site of glucan synthase was not protected with UDP-Glc when preincubated with 10 μM N-ethylmaleimide but the GTP-binding fraction was partially protected with GTPγS.Key words: Candida albicans, (1,3)-β-glucan synthase, GTP-binding proteins, solubilization, sulfhydryl reagents.

scholarly journals Cellular Accumulation, Localization, and Activity of a Synthetic Cyclopeptamine in Fungi

1998 ◽  
Vol 42 (2) ◽  
pp. 389-393 ◽  
Author(s):  
John O. Capobianco ◽  
Dorothy Zakula ◽  
David J. Frost ◽  
Robert C. Goldman ◽  
Leping Li ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Glucan Synthase ◽  
Cellular Accumulation ◽  
Drug Concentrations ◽  
Drug Reservoir ◽  
Membrane Bound ◽  
Glucan Synthesis ◽  
Major Drug

ABSTRACT A novel synthetic cyclopeptamine, A172013, rapidly accumulated by passive diffusion into Candida albicans CCH442. Drug influx could not be totally facilitated by the membrane-bound target, β-(1,3)-glucan synthase, since accumulation was unsaturable at drug concentrations up to 10 μg/ml (about 1.6 × 10−7molecules/cell), or 25× MIC. About 55 and 23% of the cell-incorporated drug was associated with the cell wall and protoplasts, respectively. Isolated microsomes contained 95% of the protoplast-associated drug, which was fully active against glucan synthesis in vitro. Drug (0.1 μg/ml) accumulation was rapid and complete after 5 min in several fungi tested, including a lipopeptide/cyclopeptamine-resistant strain of C. albicans(LP3-1). The compound penetrated to comparable levels in both yeast and hyphal forms of C. albicans, and accumulation inAspergillus niger was 20% that in C. albicans. These data indicated that drug-cell interactions were driven by the amphiphilic nature of the compound and that the cell wall served as a major drug reservoir.

scholarly journals Immunomodulating Effects of Fungal Beta-Glucans: From Traditional Use to Medicine

Nutrients ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 1333
Author(s):  
Hidde P. van Steenwijk ◽  
Aalt Bast ◽  
Alie de Boer
Keyword(s):  
Immune System ◽  
Good Health ◽  
Evidence Base ◽  
Health Claims ◽  
Bioactive Molecules ◽  
Current Status ◽  
Beta Glucan ◽  
Traditional Use ◽  
Beta Glucans ◽  
And Function

The importance of a well-functioning and balanced immune system has become more apparent in recent decades. Various elements have however not yet been uncovered as shown, for example, in the uncertainty on immune system responses to COVID-19. Fungal beta-glucans are bioactive molecules with immunomodulating properties. Insights into the effects and function of beta-glucans, which have been used in traditional Chinese medicine for centuries, advances with the help of modern immunological and biotechnological methods. However, it is still unclear into which area beta-glucans fit best: supplements or medicine? This review has highlighted the potential application of fungal beta-glucans in nutrition and medicine, reviewing their formulation, efficacy, safety profile, and immunomodulating effects. The current status of dietary fungal glucans with respect to the European scientific requirements for health claims related to the immune system and defense against pathogens has been reviewed. Comparing the evidence base of the putative health effects of fungal beta-glucan supplements with the published guidance documents by EFSA on substantiating immune stimulation and pathogen defense by food products shows that fungal beta-glucans could play a role in supporting and maintaining health and, thus, can be seen as a good health-promoting substance from food, which could mean that this effect may also be claimed if approved. In addition to these developments related to food uses of beta-glucan-containing supplements, beta-glucans could also hold a novel position in Western medicine as the concept of trained immunity is relatively new and has not been investigated to a large extent. These innovative concepts, together with the emerging success of modern immunological and biotechnological methods, suggest that fungal glucans may play a promising role in both perspectives, and that there are possibilities for traditional medicine to provide an immunological application in both medicine and nutrition.

scholarly journals beta-Furfuryl-beta-glucoside. An endogenous activator of higher plant UDP-glucose: (1—-3)-beta-glucan synthase

1991 ◽  
Vol 266 (21) ◽  
pp. 13742-13745
Author(s):  
P. Ohana ◽  
D.P. Delmer ◽  
J.C. Steffens ◽  
D.E. Matthews ◽  
R. Mayer ◽  
...  
Keyword(s):  
Higher Plant ◽  
Beta Glucan ◽  
Glucan Synthase
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