scholarly journals Rat epididymal luminal fluid acid β-d-galactosidase optimally hydrolyses glycoprotein substrate at neutral pH

1992 ◽  
Vol 286 (3) ◽  
pp. 907-914 ◽  
Author(s):  
M D Skudlarek ◽  
D R P Tulsiani ◽  
M C Orgebin-Crist
Keyword(s):  
Potential Role ◽  
Physiological Role ◽  
Maximum Activity ◽  
Neutral Ph ◽  
Mammalian Tissues ◽  
Acidic Conditions ◽  
Neutral Conditions ◽  
Molecular Sieve Column ◽  
Single Enzyme

Several glycosidases, purified and characterized from mammalian tissues, have been shown to be optimally active under acidic conditions when p-nitrophenyl (PNP) or 4-methylumbelliferyl glycosides are used as substrates. Although high levels of the glycosidases are present in the epididymal lumen, their physiological role remains uncertain. To be functional, the glycosidases are expected to be enzymatically active at or near the physiological pH of luminal fluid. In this report, we demonstrate that the rat epididymal luminal fluid beta-D-galactosidase, optimally active toward PNP beta-D-galactoside at pH 3.5, shows maximum activity towards a glycoprotein substrate ([Gal-3H]fetuin) at neutral pH. Several lines of evidence, including immunoprecipitation studies using antibody to the acid beta-D-galactosidase, and substrate competition studies, indicate that PNP galactosidase and [3H]Gal galactosidase activities are caused by a single enzyme, and that the two substrates are probably cleaved by the same catalytic site(s). Competition studies with various disaccharides indicate that this enzyme is capable of cleaving a variety of galactose linkages found in both O- and N-linked oligosaccharides. Molecular-sieve column chromatography of the beta-D-galactosidase of luminal fluid under several conditions of buffer and pH show that, whereas the enzyme eluted as a tetramer (apparent M(r) 320,000) under acidic conditions (pH 3.5-4.3), only dimers and monomers (apparent M(r) 180,000 and 92,000 respectively) were observed in neutral conditions (pH 6.8). This aggregation/dissociation phenomenon is reversible. These studies indicate that beta-D-galactosidase is present in the luminal fluid in dissociated forms, and is therefore optimally active towards glycoprotein substrates at physiological pH. The potential role of the enzyme in modification of sperm surface glycoproteins is discussed.

scholarly journals Effect of 1,5-Anhydro-D-Fructose on the Inhibition of Adipogenesis in 3T3-L1 Adipocytes

2012 ◽  
Vol 7 (11) ◽  
pp. 1934578X1200701 ◽  
Author(s):  
Akiko Kojima-Yuasa ◽  
Yohei Deguchi ◽  
Yotaro Konishi ◽  
Isao Matsui-Yuasa
Keyword(s):  
Metabolic Diseases ◽  
Physiological Role ◽  
Structural Similarity ◽  
Regulation Of Transcription ◽  
Energy Sensor ◽  
Mammalian Tissues ◽  
Cellular Lipid Accumulation ◽  
Amp Activated Protein Kinase

1,5-Anhydro-D-fructose (1,5-AF) is a monosaccharide that shares a structural similarity to glucose. 1,5-AF is found in fungi, algae, Escherichia coli and rat liver and is produced by the degradation of starch and glycogen, which is catalyzed by the enzyme α-1,4-glucan lyase. However, the physiological role of 1,5-AF in mammalian tissues is not well understood. Here, we investigated the anti-obesity potential of 1,5-AF on adipogenesis in 3T3-L1 adipocytes. 1,5-AF caused a significant decrease in GPDH activity in 3T3-L1 preadipocytes and mature adipocytes without eliciting cytotoxicity, and inhibited cellular lipid accumulation through down-regulation of transcription factors such as PPARγ and C/EBPα. 1,5-AF also induced dose-dependent phosphorylation of AMP-activated protein kinase (AMPK), a cellular energy sensor. However, the total AMPK protein content remained unchanged. Furthermore, 1,5-AF increased the levels of reactive oxygen species, an important upstream signal for AMPK activation in 3T3-L1 adipocytes. Our results show that 1,5-AF exerts anti-obesity action in vitro and suggest that 1,5-AF is potentially a novel preventative agent for obesity and other metabolic diseases.

scholarly journals Activation of Southern White Rhinoceros (Ceratotherium simum simum) Estrogen Receptors by Phytoestrogens: Potential Role in the Reproductive Failure of Captive-Born Females?

Endocrinology ◽  
2012 ◽  
Vol 153 (3) ◽  
pp. 1444-1452 ◽  
Author(s):  
Christopher Tubbs ◽  
Phillip Hartig ◽  
Mary Cardon ◽  
Nicole Varga ◽  
Matthew Milnes
Keyword(s):  
Estrogen Receptors ◽  
Potential Role ◽  
Physiological Role ◽  
Reproductive Failure ◽  
Vertebrate Species ◽  
Ceratotherium Simum ◽  
White Rhinoceros ◽  
Southern White Rhinoceros ◽  
Ceratotherium Simum Simum

The captive southern white rhinoceros (SWR; Ceratotherium simum simum) population serves as an important genetic reservoir critical to the conservation of this vulnerable species. Unfortunately, captive populations are declining due to the poor reproductive success of captive-born females. Captive female SWR exhibit reproductive problems suggested to result from continual ovarian follicular activity and prolonged exposure to endogenous estrogen. However, we investigated the potential role of exogenous dietary phytoestrogens in the reproductive failure of SWR by cloning and characterizing in vitro phytoestrogen binding and activation of recombinant SWR estrogen receptors (ESR). We compared those characteristics with recombinant greater one-horned rhinoceros (GOHR; Rhinoceros unicornis) ESR, a species that receives similar captive diets yet reproduces relatively well. Our results indicate that phytoestrogens bind rhino ESR in a manner similar to other vertebrate species, but there are no differences found in phytoestrogen binding affinity of SWR ESR compared with GOHR ESR. However, species-specific differences in ESR activation by phytoestrogens were detected. The phytoestrogen coumestrol stimulated greater maximal activation of SWR ESR1 than GOHR ESR1. SWR ESR2 were also more sensitive to phytoestrogens and were activated to a greater extent by both coumestrol and daidzein. The concentrations in which significant differences in ESR activation occurred (10−7 to 10−5m) are consistent with circulating concentrations measured in other vertebrate species. Taken together, these findings suggest that phytoestrogens potentially pose a risk to the reproductive health of captive SWR. However, additional studies are needed to further clarify the physiological role of dietary phytoestrogens in the reduced fertility of this species.

scholarly journals The Role of Autophagy in Immunity and Autoimmune Diseases / Uloga Autofagije U Imunskom Odgovoru I Autoimunskim Bolestima

2014 ◽  
Vol 15 (4) ◽  
pp. 223-229
Author(s):  
Bojana Simovic Markovic ◽  
Ljubica Vucicevic ◽  
Sanja Bojic ◽  
Vladislav Volarevic
Keyword(s):  
Autoimmune Diseases ◽  
Potential Role ◽  
Current Knowledge ◽  
Inflammatory Diseases ◽  
Physiological Role ◽  
Immune Functions ◽  
Complex Relationships ◽  
Cellular Components ◽  
Chaperone Mediated Autophagy

ABSTRACT Autophagy is a catabolic mechanism in the cell that involves the degradation of unnecessary or dysfunctional cellular components by the lysosomal machinery. Recent studies have indicated that autophagy is a source of autoantigens, thus highlighting its potential role in the pathogenesis of autoimmunity. There are at least three different forms of autophagy: macroautophagy, microautophagy and chaperone-mediated autophagy (CMA). The physiological role of autophagy is to maintain cellular homeostasis by removing long-lived, damaged proteins and dysfunctional organelles and by providing energy. Aberrant autophagy may contribute to chronic inflammatory diseases and autoimmune diseases. An understanding of the complex relationships between autophagy and autophagy-related genes in each autoimmune disease creates the possibility of developing more specific and effective therapeutic strategies. Given the importance of autophagy in immune functions, this review article summarises current knowledge about the role of autophagy in the pathogenesis of autoimmune diseases.

scholarly journals The Pyruvate Carboxylase of Verticillium albo-atrum

Microbiology ◽  
2000 ◽  
Vol 81 (1) ◽  
pp. 15-19 ◽  
Author(s):  
R. E. Hartman ◽  
N. T. Keen
Keyword(s):  
Pyruvate Carboxylase ◽  
Krebs Cycle ◽  
Physiological Role ◽  
Maximum Activity ◽  
Ph Optimum ◽  
Carboxylase Activity ◽  
Metabolic Intermediates ◽  
Krebs Cycle Intermediates ◽  
Verticillium Albo Atrum

The pyruvate carboxylase of Verticillium albo-atrum had a pH optimum of 7·8 and a specific requirement for ATP. At the optimum pH, magnesium ions were required for maximum activity, while at pH 6·8 manganese was more effective than magnesium. Potassium was stimulatory while sodium was ineffective. Avidin and p-chloromercuribenzoate strongly inhibited the enzyme while biotin and dithiothreitol, respectively, reversed the effect of the inhibitors. Aspartate and oxalacetate were inhibitory while acetyl-CoA and CoA reversed the inhibition by aspartate. These cofactors were ineffective in the absence of aspartate. None of the tested metabolic intermediates was stimulatory to pyruvate carboxylase activity while NADP+ and 2,3-diphosphoglycerate were the most effective inhibitors (75%) at a concentration of 6·7 mM. Levels of pyruvate carboxylase in cells grown on glucose, acetate, malate, xylose, glycerol or aspartate differed only slightly. The data indicated that the physiological role of pyruvate carboxylase in V. albo-atrum is the anaplerotic biosynthesis of C4 Krebs-cycle intermediates from pyruvate.

scholarly journals Cis- and Trans-Encoded Small Regulatory RNAs in Bacillus subtilis

2021 ◽  
Vol 9 (9) ◽  
pp. 1865
Author(s):  
Sabine Brantl ◽  
Peter Müller
Keyword(s):  
Potential Role ◽  
Bacterial Species ◽  
Model Organism ◽  
Physiological Role ◽  
Base Pairing ◽  
Small Regulatory Rnas ◽  
Regulatory Rnas ◽  
Rna Chaperones ◽  
Cis And Trans

Small regulatory RNAs (sRNAs) that act by base-pairing are the most abundant posttranscriptional regulators in all three kingdoms of life. Over the past 20 years, a variety of approaches have been employed to discover chromosome-encoded sRNAs in a multitude of bacterial species. However, although largely improved bioinformatics tools are available to predict potential targets of base-pairing sRNAs, it is still challenging to confirm these targets experimentally and to elucidate the mechanisms as well as the physiological role of their sRNA-mediated regulation. Here, we provide an overview of currently known cis- and trans-encoded sRNAs from B. subtilis with known targets and defined regulatory mechanisms and on the potential role of RNA chaperones that are or might be required to facilitate sRNA regulation in this important Gram-positive model organism.

scholarly journals The Association between α-Synuclein and α-Tubulin in Brain Synapses

2021 ◽  
Vol 22 (17) ◽  
pp. 9153
Author(s):  
Alida Amadeo ◽  
Sara Pizzi ◽  
Alessandro Comincini ◽  
Debora Modena ◽  
Alessandra Maria Calogero ◽  
...  
Keyword(s):  
Potential Role ◽  
Physiological Role ◽  
Direct Interaction ◽  
Substantia Nigra Pars Compacta ◽  
Proximity Ligation Assay ◽  
Proximity Ligation ◽  
Cytoskeletal Component ◽  
Presynaptic Boutons

α-synuclein is a small protein that is mainly expressed in the synaptic terminals of nervous tissue. Although its implication in neurodegeneration is well established, the physiological role of α-synuclein remains elusive. Given its involvement in the modulation of synaptic transmission and the emerging role of microtubules at the synapse, the current study aimed at investigating whether α-synuclein becomes involved with this cytoskeletal component at the presynapse. We first analyzed the expression of α-synuclein and its colocalization with α-tubulin in murine brain. Differences were found between cortical and striatal/midbrain areas, with substantia nigra pars compacta and corpus striatum showing the lowest levels of colocalization. Using a proximity ligation assay, we revealed the direct interaction of α-synuclein with α-tubulin in murine and in human brain. Finally, the previously unexplored interaction of the two proteins in vivo at the synapse was disclosed in murine striatal presynaptic boutons through multiple approaches, from confocal spinning disk to electron microscopy. Collectively, our data strongly suggest that the association with tubulin/microtubules might actually be an important physiological function for α-synuclein in the synapse, thus suggesting its potential role in a neuropathological context.

scholarly journals Sulfation of Thyroid Hormone by Estrogen Sulfotransferase

1999 ◽  
Vol 84 (7) ◽  
pp. 2577-2580 ◽  
Author(s):  
M. H. A. Kester ◽  
C. H. van Dijk ◽  
D. Tibboel ◽  
A. M. Hood ◽  
N. J. M. Rose ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Potential Role ◽  
Estrogen Sulfotransferase ◽  
Hormone Metabolism ◽  
Thyroid Hormone Metabolism ◽  
Fetal Thyroid ◽  
First Time ◽  
Very High ◽  
Single Enzyme

Sulfation is one of the pathways by which thyroid hormone is inactivated. Iodothyronine sulfate concentrations are very high in human fetal blood and amniotic fluid, suggesting important production of these conjugates in utero. Human estrogen sulfotransferase (SULT1E1) is expressed among other tissues in the uterus. Here we demonstrate for the first time that SULT1E1 catalyzes the facile sulfation of the prohormone T4, the active hormone T3 and the metabolites rT3 and 3,3′-diiodothyronine (3,3′-T2) with preference for rT3 ≈ 3,3′-T2 > T3 ≈ T4. Thus, a single enzyme is capable of sulfating two such different hormones as the female sex hormone and thyroid hormone. The potential role of SULT1E1 in fetal thyroid hormone metabolism needs to be considered.

The effect of methyl lidocaine on lysophospholipid metabolism in hamster heart

1990 ◽  
Vol 68 (4) ◽  
pp. 745-750 ◽  
Author(s):  
Paul G. Tardi ◽  
Ricky Y. K. Man ◽  
Christopher R. McMaster ◽  
Patrick C. Choy
Keyword(s):  
Physiological Role ◽  
Fatty Acyl ◽  
The Other ◽  
Acylation Reaction ◽  
Alternate Pathway ◽  
Mammalian Tissues ◽  
High Concern ◽  
Acyl Chains ◽  
Hamster Heart

An important feature in the remodelling of fatty acyl chains in cellular phospholipids is the acylation of lysophospholipids. Since lysophospholipids are cytolytic al high concern rat ions, the acylation reaction may provide an alternate pathway for the removal of cellular lysophospholipids. However, the physiological role of the acylation process in the maintenance of lysophospholipid levels in mammalian tissues has not been clearly defined. In this study, methyl lidocaine was found to inhibit both lysophosphatidylcholine:acyl-CoA and lysophosphatidylethanolamine:acyl-CoA acyltransferase activities in the hamster heart, but the drug had no effect on the other lysophospholipid metabolic enzymes. When the heart was perfused with 0.5 mg methyl lidocaine/mL, acyltransferase activities were attenuated, but there was no change in the activities of phospholipase A or lysophospholipase. The levels of the major lysophospholipids in the heart were not altered by methyl lidocaine perfusion. When the hearts were perfused with labelled lysophospholipid in the presence of methyl lidocaine, there was a reduction in the formation of the phospholipid and an increase in the release of the free fatty acid. However, the labelling of lysophospholipid in the heart was not altered by methyl lidocaine. We postulate that the acylation reaction has no direct contribution to the maintenance of the lysophospholipid levels in the heart.Key words: lysophosphatidylcholine, lysophosphatidylethanolamine, acyltransferase, methyl lidocaine, hamster heart.

scholarly journals An evolutionarily conserved enzyme degrades transforming growth factor-alpha as well as insulin.

1989 ◽  
Vol 109 (3) ◽  
pp. 1301-1307 ◽  
Author(s):  
J V Garcia ◽  
B D Gehm ◽  
M R Rosner
Keyword(s):  
Growth Factor ◽  
Mammalian Cells ◽  
Transforming Growth Factor ◽  
Physiological Role ◽  
Evolutionary Conservation ◽  
Transforming Growth Factor Alpha ◽  
Evolutionarily Conserved ◽  
Factor Alpha ◽  
Single Enzyme

A single enzyme found in both Drosophila and mammalian cells is able to selectively bind and degrade transforming growth factor (TGF)-alpha and insulin, but not EGF, at physiological concentrations. These growth factors are also able to inhibit binding and degradation of one another by the enzyme. Although there are significant immunological differences between the mammalian and Drosophila enzymes, the substrate specificity has been highly conserved. These results demonstrate the existence of a selective TGF-alpha-degrading enzyme in both Drosophila and mammalian cells. The evolutionary conservation of the ability to degrade both insulin and TGF-alpha suggests that this property is important for the physiological role of the enzyme and its potential for regulating growth factor levels.

scholarly journals Caenorhabditis elegans germline development requires brap-2

2018 ◽  
Author(s):  
Dayana R D'Amora ◽  
Queenie Hu ◽  
Monica Pizzardi ◽  
Terrance Kubiseski
Keyword(s):  
Ubiquitin Ligase ◽  
Brood Size ◽  
Potential Role ◽  
Chromosomal Abnormalities ◽  
E3 Ubiquitin Ligase ◽  
Retention Factor ◽  
Germline Development ◽  
C Elegans ◽  
Mammalian Tissues

Background. Mutations in C. elegans can produce visible and quantifiable defects in morphology, lifespan, and development. BRAP2/IMP (BRCA1-associated binding protein 2) has been characterized as an E3 ubiquitin ligase, a general cytoplasmic retention factor, a potential scaffold protein, and is found to be widely expressed throughout various mammalian tissues, most highly in testes. However, its role in the development or health of these tissues has not been addressed. Results. The focus of this study is to determine the role of BRAP-2 in C. elegans germline development. We determined that brap-2 mutants display defects in germline morphology and a reduction in brood size. We also found that chromosomal abnormalities and embryonic lethality are elevated in brap-2 mutants following DNA damage, suggesting a potential role for BRAP-2 in facilitating DNA repair. Conclusions. Our findings indicate that BRAP-2 is required for C. elegans germline health and identifies a novel role for BRAP-2 in germline development.

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