ACC-N-Malonyltransferase activity during zygotic embryogenesis and germination of chick-pea seeds

2000 ◽  
Vol 10 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Clemente Martin-Remesal ◽  
Maria del Carmen Gomez-Jimenez ◽  
Angel J. Matilla
Keyword(s):  
Enzymatic Activity ◽  
Specific Activity ◽  
Embryonic Axis ◽  
Zygotic Embryogenesis ◽  
Chick Pea ◽  
Low Concentrations ◽  
Mtase Activity ◽  
Storage Organs ◽  
Radicle Emergence

AbstractSome physiological characteristics of ACC-Nmalonyltransferase (ACC-N-MTase) have been studied in the seeds of chick-pea (Cicer arietinum L.). This enzymatic activity was detectable during all periods of zygotic embryogenesis; however, the highest values were found in the dry seed. In dry seeds, the enzymatic activity was greater in the embryonic axis than in the cotyledons. During the onset of germination, activity increased more strongly in the cotyledons than in the embryonic axis, reaching its highest values in the storage organs coinciding with radicle emergence (18 to 24 h). Removal of the cotyledons strongly diminished enzymatic activity in the embryonic axis. Low concentrations of ethrel (50 µM) stimulated the axis ACC-N-MTase. The highest specific activity was found in the apical meristem of the embryonic axis, declining over the length of the organ. The role of ACC-N-MTase activity in the germinative process is discussed, together with the regulatory effect of ethylene on this ACCconjugating enzyme.

Activation of detergent-solubilized rat hepatic 5′-iodothyronine deiodinase by NADPH and nonglutathione cytosolic components

1988 ◽  
Vol 66 (1) ◽  
pp. 71-76
Author(s):  
Kenzo Sawada ◽  
Brian C. W. Hummel ◽  
Paul G. Walfish
Keyword(s):  
Specific Activity ◽  
Microsomal Membrane ◽  
Relative Mass ◽  
Fractional Precipitation ◽  
Iodothyronine Deiodinase ◽  
Low Concentrations ◽  
Similar Dependence ◽  
Maximal Activation ◽  
Cytosolic Factors

An investigation was made of the possible role of the hepatic microsomal membrane in the activation of 5′-iodothyronine deiodinase (5′-DI) by a cytosolic activating system consisting of fraction A (relative mass (Mr) > 60000), fraction B (Mr, approximately 13 000), and NADPH. Activation of 5′-DI in washed microsomes was compared with that of a microsome extract prepared by solubilization with 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulphonate and further purification by fractional precipitation with polyethylene glycol and by DEAE-Sephacel chromatography. All 5′-DI preparations exhibited qualitatively similar dependence upon NADPH and cytosolic factors in fractions A and B for 5′-DI activation and were relatively unresponsive to NADH. Activation of solubilized preparations, unlike that of intact microsomes, was more readily inhibited by low concentrations of detergent and not inhibited by NADPH concentrations above 0.25 mM. Attempted purification of 5′-DI failed to produce a substantial increase in specific activity of the enzyme. It is concluded that, while glutathione-independent cytosolic factors and NADPH can activate 5′-DI in the absence of an intact microsomal membrane, some membrane constituents removed during solubilization and purification of the enzyme are required for maximal activation.

scholarly journals α-galactosidase activity and carbohydrate mobilization in seeds of Dalbergia nigra (vell.) Allemão ex Benth. - fabaceae (Brazilian rosewood) during germination

CERNE ◽  
2010 ◽  
Vol 16 (3) ◽  
pp. 283-289 ◽  
Author(s):  
Lanna Clicia Carrijo ◽  
Eduardo Euclydes de Lima e Borges ◽  
Claudia Aparecida Pontes ◽  
Mariana Rocha Lopes ◽  
Arno Brune
Keyword(s):  
Enzyme Activity ◽  
Specific Activity ◽  
Continuous Light ◽  
Physical Structure ◽  
Embryonic Axis ◽  
Galactosidase Activity ◽  
Germination Process ◽  
Radicle Emergence ◽  
Dalbergia Nigra ◽  
Plant Embryo

Complex substances are converted by enzyme action into soluble molecules during the germination process, and these are in turn translocated to the growing plant embryo, serving as an energy source or physical structure. With the objective of quantifying α-galactosidase enzyme activity as well as mono-and oligosaccharide mobilization during germination, this study was conducted using Brazilian rosewood seeds. Seeds were kept in a germinator at 25ºC under continuous light for evaluation of radicle emergence (protrusion) over a period of 10 days. Mono-and oligosaccharide contents and also the specific activity of α-galactosidase enzyme were quantified on days zero, one, three and five. There was mobilization of glucose and mannose stored in cotyledons, and also of xylose in cotyledons and in the embryo in the first three days of germination. Rhamnose contents increased in cotyledons and in the embryonic axis. Raffinose was the initially used oligosaccharide, both in the embryonic axis and in cotyledons, while sucrose accumulated in both. Enzyme activity varied throughout, with greater specific activity on day one of imbibition, both in cotyledons and in the embryonic axis.

Ethylene in seed formation and germination

2000 ◽  
Vol 10 (2) ◽  
pp. 111-126 ◽  
Author(s):  
Angel J. Matilla
Keyword(s):  
Acc Oxidase ◽  
Ethylene Biosynthesis ◽  
Gas Production ◽  
Embryonic Axis ◽  
Zygotic Embryogenesis ◽  
Seed Formation ◽  
Germination Process ◽  
Breaking Dormancy ◽  
Tissue Sensitivity

AbstractAbstract In seed formation the role of ethylene has received little attention. The data available on zygotic embryogenesis suggest an association of the ethylene biosynthetic pathway and seed maturation. Over the course of dicot embryogenesis, ACC-oxidase mRNA can be expressed in the cotyledons and embryonic axis. However, as maturation proceeds, cotyledonary ACC-oxidase expression disappears. In some seeds that develop primary dormancy, ethylene synthesis can be among the prerequisites for breaking dormancy. Moreover, the persistence of dormancy may be related to the difficulty of the embryonic axis to produce the necessary ethylene levels or to low tissue sensitivity. The use of inhibitors of ethylene biosynthesis or its action has provided data implicating an ethylene requirement for seed dormancy or germination in some species. However, the role of ethylene in germination remains controversial. Some authors hold that gas production is a consequence of the germination process, while others contend that ethylene production is a requirement for germination. Furthermore, among seeds that require ethylene, some are extremely sensitive to the gas, while others require relatively high levels to trigger germination. Recent studies withXanthium pennsylvanicumseeds suggest that β-cyanoalanine-synthase is involved in ethylene-dependent germination. In addition, regulation of the partitioning ofS-adenosyl-L-methionine (AdoMet) between the ethylene vs polyamine biosynthetic pathways may be a way of controlling germination in some seeds. Such regulation may also apply to the reversal of seed thermoinhibition, which can occur when polyamine synthesis is inhibited, thereby strongly channelling AdoMet towards ethylene. The biological models and approaches that may shed additional light on the role of ethylene during seed germination are presented.

Testosterone Potentiation of Ionophore and ADP Induced Platelet Aggregation : Relationship to Arachidonic Acid Metabolism

1981 ◽  
Vol 46 (02) ◽  
pp. 538-542 ◽  
Author(s):  
R Pilo ◽  
D Aharony ◽  
A Raz
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Unsaturated Fatty Acids ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Arachidonic Acid Metabolism ◽  
Ionophore A23187 ◽  
Low Concentrations ◽  
Induced Aggregation

SummaryThe role of arachidonic acid oxygenated products in human platelet aggregation induced by the ionophore A23187 was investigated. The ionophore produced an increased release of both saturated and unsaturated fatty acids and a concomitant increased formation of TxA2 and other arachidonate products. TxA2 (and possibly other cyclo oxygenase products) appears to have a significant role in ionophore-induced aggregation only when low concentrations (<1 μM) of the ionophore are employed.Testosterone added to rat or human platelet-rich plasma (PRP) was shown previously to potentiate platelet aggregation induced by ADP, adrenaline, collagen and arachidonic acid (1, 2). We show that testosterone also potentiates ionophore induced aggregation in washed platelets and in PRP. This potentiation was dose and time dependent and resulted from increased lipolysis and concomitant generation of TxA2 and other prostaglandin products. The testosterone potentiating effect was abolished by preincubation of the platelets with indomethacin.

scholarly journals Potential Dual Role of West Nile Virus NS2B in Orchestrating NS3 Enzymatic Activity in Viral Replication

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 216
Author(s):  
Alanna C. Tseng ◽  
Vivek R. Nerurkar ◽  
Kabi R. Neupane ◽  
Helmut Kae ◽  
Pakieli H. Kaufusi
Keyword(s):  
West Nile Virus ◽  
Enzymatic Activity ◽  
Nonstructural Protein ◽  
Antiviral Drug ◽  
West Nile ◽  
Biochemical Assays ◽  
In Trans ◽  
Viral Polyprotein ◽  
Ns3 Protease

West Nile virus (WNV) nonstructural protein 3 (NS3) harbors the viral triphosphatase and helicase for viral RNA synthesis and, together with NS2B, constitutes the protease responsible for polyprotein processing. NS3 is a soluble protein, but it is localized to specialized compartments at the rough endoplasmic reticulum (RER), where its enzymatic functions are essential for virus replication. However, the mechanistic details behind the recruitment of NS3 from the cytoplasm to the RER have not yet been fully elucidated. In this study, we employed immunofluorescence and biochemical assays to demonstrate that NS3, when expressed individually and when cleaved from the viral polyprotein, is localized exclusively to the cytoplasm. Furthermore, NS3 appeared to be peripherally recruited to the RER and proteolytically active when NS2B was provided in trans. Thus, we provide evidence for a potential additional role for NS2B in not only serving as the cofactor for the NS3 protease, but also in recruiting NS3 from the cytoplasm to the RER for proper enzymatic activity. Results from our study suggest that targeting the interaction between NS2B and NS3 in disrupting the NS3 ER localization may be an attractive avenue for antiviral drug discovery.

scholarly journals Impaired platelet responses to thrombin and collagen in AKT-1–deficient mice

Blood ◽  
2004 ◽  
Vol 104 (6) ◽  
pp. 1703-1710 ◽  
Author(s):  
Juhua Chen ◽  
Sarmishtha De ◽  
Derek S. Damron ◽  
William S. Chen ◽  
Nissim Hay ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Ex Vivo ◽  
Dense Granules ◽  
Fibrinogen Binding ◽  
Downstream Effectors ◽  
Low Concentrations ◽  
Phosphoinositide 3 Kinase ◽  
Deficient Mice ◽  
Granule Release

Abstract We investigated the role of Akt-1, one of the major downstream effectors of phosphoinositide 3-kinase (PI3K), in platelet function using mice in which the gene for Akt-1 had been inactivated. Using ex vivo techniques, we showed that Akt-1-deficient mice exhibited impaired platelet aggregation and spreading in response to various agonists. These differences were most apparent in platelets activated with low concentrations of thrombin. Although Akt-1 is not the predominant Akt isoform in mouse platelets, its absence diminished the amount of total phospho-Akt and inhibited increases in intracellular Ca2+ concentration in response to thrombin. Moreover, thrombin-induced platelet α-granule release as well as release of adenosine triphosphate from dense granules was also defective in Akt-1-null platelets. Although the absence of Akt-1 did not influence expression of the major platelet receptors for thrombin and collagen, fibrinogen binding in response to these agonists was significantly reduced. As a consequence of impaired αIIbβ3 activation and platelet aggregation, Akt-1 null mice showed significantly longer bleeding times than wild-type mice. (Blood. 2004;104:1703-1710)

Acetylsalicylic acid hydrolase of gastric mucosa.

1978 ◽  
Vol 234 (6) ◽  
pp. E606
Author(s):  
J G Spenney
Keyword(s):  
Gastric Mucosa ◽  
Enzymatic Activity ◽  
Acetylsalicylic Acid ◽  
Sodium Dodecyl ◽  
Sodium Cholate ◽  
Acid Hydrolase ◽  
Sulfhydryl Reagents ◽  
Ph Optimum ◽  
Diisopropyl Fluorophosphate

Acetylsalicylic acid hydrolase activity of rabbit fundic gastric mucosa has been isolated from the soluble 100,000 X g supernate. The enzymatic activity was partially purified by ammonium sulfate precipitation. The Km for acetylsalicylate was 2 mM and pH optimum was 8.6. The activity was insensitive to ionic strength, slightly inhibited by inclusion of 100 mM Cl-, and demonstrated no requirement for Ca2+ or Mg2+. Acetylsalicylic acid esterase was markedly inhibited by sodium cholate and sodium dodecyl sulfate. The enzyme was insensitive to sulfhydryl reagents with the exception of p-chloromercuribenzenesulfonic acid, which markedly inhibited the enzyme. Diisopropyl fluorophosphate (DFP) inhibited enzymatic activity with a Ki of 9 X 10(-9)M. Eserine was also inhibitory with a Ki of 0.25 mM. Inhibition by DFP at low concentration and by eserine at millimolar concentrations suggests that this enzyme is related to the group of aliphatic esterases. Identification of potent inhibitors will enable studies to define the role of this enzyme with the use of experimental preparations in which systemic toxicity can be avoided.

Obesity and inflammatory bowel disease

2021 ◽  
Vol 75 (1) ◽  
pp. 20-28
Author(s):  
Vladimír Teplan ◽  
Milan Lukáš
Keyword(s):  
Inflammatory Bowel Disease ◽  
Adipose Tissue ◽  
Bowel Disease ◽  
Intestinal Inflammation ◽  
Perioperative Complications ◽  
Overweight And Obesity ◽  
Special Role ◽  
Low Concentrations ◽  
Inflammatory Bowel

The incidence and prevalence of overweight and obesity has dramatically increased in the last decades and is generally considered to be global pandemics. The incidence of inflammatory bowel disease (IBD) is rising parallel with overweight and obesity. Contrary to a conventional believe, about 15–40% patients with IBD are obese, which can contribute to the development and course of IBD, especially in Crohn’s disease. Although the findings of some cohort studies are still conflicting, recent results indicate a special role of visceral adipose tissue and particularly mesenteric adipose tissue known as creeping fat, leading to intestinal inflammation. The involvement of altered adipocyte function and deregulated production of adipokines such as leptin and adiponectin has been suggested in the pathogenesis of IBD. The emerging role of Western diet and microbiota can also open new possibilities in IBD management. The effect of obesity on the IBD-related therapy remains to be studied. The finding that obesity results in suboptimal response to the therapy, potentially promoting rapid clearance of biologic agents and thus leading to their low concentrations, has a great importance. Obesity also makes IBD colorectal surgery technically challenging and might increase a risk of perioperative complications.

Effects of nonsulfur and sulfur amino acids on the regulation of hepatic enzymes of cysteine metabolism

1999 ◽  
Vol 277 (1) ◽  
pp. E144-E153 ◽  
Author(s):  
Deborah L. Bella ◽  
Christine Hahn ◽  
Martha H. Stipanuk
Keyword(s):  
Amino Acids ◽  
Specific Activity ◽  
Mrna Level ◽  
Basal Diet ◽  
Cysteine Dioxygenase ◽  
Sulfur Amino Acids ◽  
Subunit Mrna ◽  
Cysteine Metabolism ◽  
Glutamylcysteine Synthetase

To determine the role of nonsulfur vs. sulfur amino acids in regulation of cysteine metabolism, rats were fed a basal diet or diets supplemented with a mixture of nonsulfur amino acids (AA), sulfur amino acids (SAA), or both for 3 wk. Hepatic cysteine-sulfinate decarboxylase (CSDC), cysteine dioxygenase (CDO), and γ-glutamylcysteine synthetase (GCS) activity, concentration, and mRNA abundance were measured. Supplementation with AA alone had no effect on any of these measures. Supplementation of the basal diet with SAA, with or without AA, resulted in a higher CDO concentration (32–45 times basal), a lower CSDC mRNA level (49–64% of basal), and a lower GCS-heavy subunit mRNA level (70–76%). The presence of excess SAA and AA together resulted in an additional type of regulation: a lower specific activity of all three enzymes was observed in rats fed diets with an excess of AA and SAA. Both SAA and AA played a role in regulation of these three enzymes of cysteine metabolism, but SAA had the dominant effects, and effects of AA were not observed in the absence of SAA.

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