scholarly journals Degradation of pyrene-labelled phospholipids by lysosomal phospholipases in vitro. Dependence of degradation on the length and position of the labelled and unlabelled acyl chains

1996 ◽  
Vol 315 (3) ◽  
pp. 947-952 ◽  
Author(s):  
S Lusa ◽  
M Myllarniemi ◽  
K Volmonen ◽  
M Vauhkonen ◽  
P Somerharju
Keyword(s):  
Fatty Acid ◽  
Acyl Chain ◽  
Upward Movement ◽  
Lysosomal Degradation ◽  
Acyl Chains ◽  
Rate Of Hydrolysis ◽  
Carboxy Terminal ◽  
Hydrolysis Of

The hydrolysis of pyrenylacyl phosphatidylcholines (PyrnPCs) (n indicates the number of aliphatic carbons in the pyrene-chain) by crude lysosomal phospholipases in vitro was investigated. PyrnPCs consist of several sets in which the length of the pyrene-labelled or the unlabelled acyl chain, linked to the sn-1 or sn-2 position, was systematically varied. Lysophosphatidylcholine and fatty acid were the only fluorescent breakdown products detected, thus indicating that PyrnPCs were degraded by A-type phospholipases and lysophospholipases. Of these, mainly A1-type phospholipases appear to be involved, as determined from the relative amounts of labelled fatty acid and lysolipid released from the positional isomers. Based on the effects of the length and position of the pyrene-labelled and unlabelled chains it is suggested that (1) the lysosomal A-type phospholipases acting on PyrnPCs recognize the carboxy-terminal part of the lipid acyl chains and (2) the relevant part of the binding site is relatively narrow. Thus phospholipids with added bulk in the corresponding region, such as those that are peroxidized and polymerized, may not be good substrates for the lysosomal phospholipases mentioned. The impaired hydrolysis of the most hydrophobic PyrnPCs indicates that lysosomal phospholipases may not be able to penetrate significantly into the substrate interphase, but upward movement of the lipid may be required for efficient hydrolysis. Finally, the rate of hydrolysis of many pyrenyl derivatives was found to be comparable to that of a natural phosphatidylcholine species, both in micelles and in lipoprotein particles, indicating that these derivatives can be used as faithful reporters of lysosomal degradation of natural lipids in vivo and in vitro.

Studies on the mechanism of acute inhibition of thyroglobulin hydrolysis by iodine

1985 ◽  
Vol 108 (4) ◽  
pp. 511-517 ◽  
Author(s):  
Nandalal Bagchi ◽  
Birdie Shivers ◽  
Thomas R. Brown
Keyword(s):  
Time Course ◽  
Period 2 ◽  
Iodotyrosine Deiodinase ◽  
Rate Of Hydrolysis ◽  
Underlying Mechanisms ◽  
Excess Iodide ◽  
Sites Of Action ◽  
Hydrolysis Of

Abstract. Iodine in excess is known to acutely inhibit thyroidal secretion. In the present study we have characterized the time course of the iodine effect in vitro and investigated the underlying mechanisms. Labelled thyroid glands were cultured in vitro in medium containing mononitrotyrosine, an inhibitor of iodotyrosine deiodinase. The rate of hydrolysis of labelled thyroglobulin was measured as the proportion of labelled iodotyrosines and iodothyronines recovered at the end of culture and was used as an index of thyroidal secretion. Thyrotrophin (TSH) administered in vivo acutely stimulated the rate of thyroglobulin hydrolysis. Addition of Nal to the culture medium acutely inhibited both basal and TSH-stimulated thyroglobulin hydrolysis. The effect of iodide was demonstrable after 2 h, maximal after 6 h and was not reversible upon removal of iodide. Iodide abolished the dibutyryl cAMP induced stimulation of thyroglobulin hydrolysis. Iodide required organic binding of iodine for its effect but new protein or RNA synthesis was not necessary. The inhibitory effects of iodide and lysosomotrophic agents such as NH4C1 and chloroquin on thyroglobulin hydrolysis were additive suggesting different sites of action. Iodide added in vitro altered the distribution of label in prelabelled thyroglobulin in a way that suggested increased coupling in the thyroglobulin molecule. These data indicate that 1) the iodide effect occurs progressively over a 6 h period, 2) continued presence of iodide is not necessary once the inhibition is established, 3) iodide exerts its action primarily at a post cAMP, prelysosomal site and 4) the effect requires organic binding of iodine, but not new RNA or protein synthesis. Our data are consistent with the hypothesis that excess iodide acutely inhibits thyroglobulin hydrolysis by increasing the resistance of thyroglobulin to proteolytic degradation through increased iodination and coupling.

Repeated thyrotrophin stimulation of thyroid secretion: lack of refractoriness in vivo

1985 ◽  
Vol 106 (2) ◽  
pp. 153-157
Author(s):  
N. Bagchi ◽  
T. R. Brown
Keyword(s):  
Adenylate Cyclase ◽  
Thyroid Tissue ◽  
Control Group ◽  
Cyclic Amp Accumulation ◽  
Thyroid Glands ◽  
Rate Of Hydrolysis ◽  
Thyroid Secretion ◽  
Hydrolysis Of

ABSTRACT It has been reported that prior exposure of thyroid tissue to TSH in vitro induces a state of refractoriness to new challenges of the hormone. We have investigated the effect of repeated TSH treatment on thyroid secretion to determine whether such refractoriness exists in vivo. The rate of thyroid secretion was estimated by measuring the rate of hydrolysis of labelled thyroglobulin from mouse thyroid glands in vitro. The thyroid glands were labelled in vivo with 131I and then cultured for 20 h in the presence of mononitrotyrosine, an inhibitor of iodotyrosine deiodinase. The rate of hydrolysis of labelled thyroglobulin was measured as the percentage of radioactivity released as free iodotyrosines and iodothyronines into the gland and the medium at the end of incubation. Thyrotrophin was administered in vivo at hourly intervals for 2–4 injections. The corresponding control group received saline injections every hour except for the last injection when they received TSH. The peak rates of thyroglobulin hydrolysis, measured 2 h following the last injection, were similar in animals receiving two, three or four TSH injections and were not different from those in the control groups. Serum tri-iodothyronine and thyroxine concentrations 2 h after the last injection were higher in the groups receiving multiple TSH injections. Thyroidal cyclic AMP accumulation in response to TSH was markedly depressed in the group receiving multiple injections compared with the group receiving a single injection of TSH in vivo. These data indicate that (1) the stimulatory effect of TSH on thyroidal secretion is not diminished by prior administration of the hormone in vivo, (2) repeated TSH administrations in vivo cause refractoriness of the adenylate cyclase response to TSH and (3) a dichotomy exists between the secretory response and the adenylate cyclase response to repeated administrations of TSH. J. Endocr. (1985) 106, 153–157

A new succinylcholine-based assay of plasma cholinesterase.

1984 ◽  
Vol 30 (2) ◽  
pp. 192-195 ◽  
Author(s):  
M H Abernethy ◽  
P M George ◽  
V E Melton
Keyword(s):  
Hydrogen Peroxide ◽  
Enzyme Activity ◽  
Plasma Cholinesterase ◽  
Choline Oxidase ◽  
Rate Of Hydrolysis ◽  
The Mean ◽  
Variant Enzyme ◽  
Hydrolysis Of

Abstract We describe a new method for measuring the in vitro rate of hydrolysis of the muscle relaxant succinylcholine. This substrate is hydrolyzed by plasma cholinesterase (EC 3.1.1.8). The resulting choline is determined by measuring the hydrogen peroxide formed on its oxidation by choline oxidase (EC 1.1.3.17). This is done by use of phenol and aminoantipyrine coupled to peroxidase, and yields an intense chromophore, Amax 500 nm. The assay requires 0.1 mL of plasma, and is precise and specific. The CV was 2.7% within run, 7.3% between run. For the usual (U variant) enzyme the Km is 53 mumol/L. Enzyme activity is removed by anticholinesterase antiserum, and is inhibited by dibucaine with a Ki of 2 mumol/L. Ten samples can be assayed in duplicate in an hour. This method is suited to routine use in any laboratory that has a simple spectrophotometer. The mean activity in 11 individuals with the cholinesterase phenotype UU was 105 U/L, for seven UA heterozygotes 61 U/L, and for three AA homozygotes 4 U/L. To the extent allowed by extrapolation from in vitro to in vivo results, this method should increase diagnostic accuracy and may directly predict duration of succinylcholine-induced apnea.

scholarly journals SMb20651 is another acyl carrier protein from Sinorhizobium meliloti

Microbiology ◽  
2009 ◽  
Vol 155 (1) ◽  
pp. 257-267 ◽  
Author(s):  
Ana Laura Ramos-Vega ◽  
Yadira Dávila-Martínez ◽  
Christian Sohlenkamp ◽  
Sandra Contreras-Martínez ◽  
Sergio Encarnación ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Sinorhizobium Meliloti ◽  
Fatty Acid Biosynthesis ◽  
Acyl Carrier Protein ◽  
Fatty Acyl ◽  
Acyl Carrier Proteins ◽  
Coa Ligase ◽  
Acyl Chains

Acyl carrier proteins (ACPs) are small acidic proteins that carry growing acyl chains during fatty acid or polyketide synthesis. In rhizobia, there are four different and well-characterized ACPs: AcpP, NodF, AcpXL and RkpF. The genome sequence of Sinorhizobium meliloti 1021 reveals two additional ORFs that possibly encode additional ACPs. One of these, smb20651, is located on the plasmid pSymB as part of an operon. The genes of the operon encode a putative asparagine synthetase (AsnB), the predicted ACP (SMb20651), a putative long-chain fatty acyl-CoA ligase (SMb20650) and a putative ammonium-dependent NAD+ synthetase (NadE1). When SMb20651 was overexpressed in Escherichia coli, [3H]β-alanine, a biosynthetic building block of 4′-phosphopantetheine, was incorporated into the protein in vivo. The purified SMb20651 was modified with 4′-phosphopantetheine in the presence of S. meliloti holo-ACP synthase (AcpS). Also, holo-SMb20651 was modified in vitro with a malonyl group by malonyl CoA-ACP transacylase. In E. coli, coexpression of SMb20651 together with other proteins such as AcpS and SMb20650 led to the formation of additional forms of SMb20651. In this bacterium, acylation of SMb20651 with C12 : 0 or C18 : 0 fatty acids was detected, demonstrating that this protein is involved in fatty acid biosynthesis or transfer. Expression of SMb20651 was detected in S. meliloti as holo-SMb20651 and acyl-SMb20651.

scholarly journals In Vitro and In Vivo Activities of Syn2190, a Novel β-Lactamase Inhibitor

1999 ◽  
Vol 43 (8) ◽  
pp. 1895-1900 ◽  
Author(s):  
Kouichi Nishida ◽  
Chieko Kunugita ◽  
Tatsuya Uji ◽  
Fusahiro Higashitani ◽  
Akio Hyodo ◽  
...  
Keyword(s):  
Systemic Infection ◽  
Side Chain ◽  
Infection Model ◽  
Morganella Morganii ◽  
Infection Models ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Group 1

ABSTRACT Syn2190, a monobactam derivative containing 1,5-dihydroxy-4-pyridone as the C-3 side chain, is a potent inhibitor of group 1 β-lactamase. The concentrations of inhibitor needed to reduce the initial rate of hydrolysis of substrate by 50% for Syn2190 against these enzymes were in the range of 0.002 to 0.01 μM. These values were 220- to 850-fold lower than those of tazobactam. Syn2190 showed in vitro synergy with ceftazidime and cefpirome. This synergy was dependent on the concentration of the inhibitor against group 1 β-lactamase-producing strains, such as Pseudomonas aeruginosa, Enterobacter cloacae, Citrobacter freundii, and Morganella morganii. However, against β-lactamase-derepressed mutants of P. aeruginosa, the MICs of ceftazidime plus Syn2190 were not affected by the amount of β-lactamase, and the values were the same for the parent strains. The MICs at which 50% of isolates are inhibited (MIC50s) of ceftazidime plus Syn2190 were 2- to 16-fold lower than those of ceftazidime alone for ceftazidime-resistant, clinically isolated gram-negative bacteria. Similarly, the MIC50s of cefpirome plus Syn2190 were two- to eightfold lower for cefpirome-resistant clinical isolates. The synergies of Syn2190 plus ceftazidime or cefpirome observed in vitro were also reflected in vivo. Syn2190 improved the efficacies of both cephalosporins in both a murine systemic infection model with cephalosporin-resistant rods and urinary tract infection models with cephalosporin-resistant P. aeruginosa.

scholarly journals Nitro-fatty acids as activators of hSIRT6 deacetylase activity

2020 ◽  
Vol 295 (52) ◽  
pp. 18355-18366
Author(s):  
Mara Carreño ◽  
Mariana Bresque ◽  
Matías R. Machado ◽  
Leonardo Santos ◽  
Rosario Durán ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Fatty Acid ◽  
Oxidative Dna Damage ◽  
Acyl Chain ◽  
Michael Adduct ◽  
Age Related ◽  
Glucose And Lipid Homeostasis

Sirtuin 6, SIRT6, is critical for both glucose and lipid homeostasis and is involved in maintaining genomic stability under conditions of oxidative DNA damage such as those observed in age-related diseases. There is an intense search for modulators of SIRT6 activity, however, not many specific activators have been reported. Long acyl-chain fatty acids have been shown to increase the weak in vitro deacetylase activity of SIRT6 but this effect is modest at best. Herein we report that electrophilic nitro-fatty acids (nitro-oleic acid and nitro-conjugated linoleic acid) potently activate SIRT6. Binding of the nitro-fatty acid to the hydrophobic crevice of the SIRT6 active site exerted a moderate activation (2-fold at 20 μm), similar to that previously reported for non-nitrated fatty acids. However, covalent Michael adduct formation with Cys-18, a residue present at the N terminus of SIRT6 but absent from other isoforms, induced a conformational change that resulted in a much stronger activation (40-fold at 20 μm). Molecular modeling of the resulting Michael adduct suggested stabilization of the co-substrate and acyl-binding loops as a possible additional mechanism of SIRT6 activation by the nitro-fatty acid. Importantly, treatment of cells with nitro-oleic acid promoted H3K9 deacetylation, whereas oleic acid had no effect. Altogether, our results show that nitrated fatty acids can be considered a valuable tool for specific SIRT6 activation, and that SIRT6 should be considered as a molecular target for in vivo actions of these anti-inflammatory nitro-lipids.

scholarly journals Trehalose diester glycolipids are superior to the monoesters in binding to Mincle, activation of macrophages in vitro and adjuvant activity in vivo

2016 ◽  
Vol 22 (6) ◽  
pp. 405-418 ◽  
Author(s):  
Alexandra Huber ◽  
Rie S Kallerup ◽  
Karen S Korsholm ◽  
Henrik Franzyk ◽  
Bernd Lepenies ◽  
...  
Keyword(s):  
Macrophage Activation ◽  
Acyl Chain ◽  
No Production ◽  
Synthetic Analogue ◽  
Adjuvant Activity ◽  
Protein Insertion ◽  
Acyl Chains ◽  
High Concentrations

The T-cell adjuvanticity of mycobacterial cord factor trehalose 6,6'-dimycolate (TDM) is well established. The identification of the C-type lectin Mincle on innate immune cells as the receptor for TDM and its synthetic analogue trehalose 6,6'-dibehenate (TDB) has raised interest in development of synthetic Mincle ligands as novel adjuvants. Trehalose mono- (TMXs) and diesters (TDXs) with symmetrically shortened acyl chains [denoted by X: arachidate (A), stearate (S), palmitate (P), and myristate (M)] were tested. Upon stimulation of murine macrophages, G-CSF secretion and NO production were strongly augmented by all TDXs tested, in a wide concentration range. In contrast, the TMXs triggered macrophage activation only at high concentrations. Macrophage activation by all TDXs required Mincle, but was independent of MyD88. The superior capacity of TDXs for activating macrophages was paralleled by direct binding of TDXs, but not of TMXs, to a Mincle-Fc fusion protein. Insertion of a short polyethylene glycol between the sugar and acyl chain in TDS reduced Mincle-binding and macrophage activation. Immunization of mice with cationic liposomes containing the analogues demonstrated the superior adjuvant activity of trehalose diesters. Overall, immune activation in vitro and in vivo by trehalose esters of simple fatty acids requires two acyl chains of length and involves Mincle.

scholarly journals Integrated lipidomics and proteomics reveal cardiolipin alterations, upregulation of HADHA and long chain fatty acids in pancreatic cancer stem cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Claudia Di Carlo ◽  
Bebiana C. Sousa ◽  
Marcello Manfredi ◽  
Jessica Brandi ◽  
Elisa Dalla Pozza ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Stem Cells ◽  
Fatty Acid ◽  
Cancer Stem Cells ◽  
Acyl Chain ◽  
Fatty Acid Elongase ◽  
Acyl Chains ◽  
A Chain ◽  
Pancreatic Cancer Stem Cells ◽  
Long Chain

AbstractPancreatic cancer stem cells (PCSCs) play a key role in the aggressiveness of pancreatic ductal adenocarcinomas (PDAC); however, little is known about their signaling and metabolic pathways. Here we show that PCSCs have specific and common proteome and lipidome modulations. PCSCs displayed downregulation of lactate dehydrogenase A chain, and upregulation of trifunctional enzyme subunit alpha. The upregulated proteins of PCSCs are mainly involved in fatty acid (FA) elongation and biosynthesis of unsaturated FAs. Accordingly, lipidomics reveals an increase in long and very long-chain unsaturated FAs, which are products of fatty acid elongase-5 predicted as a key gene. Moreover, lipidomics showed the induction in PCSCs of molecular species of cardiolipin with mixed incorporation of 16:0, 18:1, and 18:2 acyl chains. Our data indicate a crucial role of FA elongation and alteration in cardiolipin acyl chain composition in PCSCs, representing attractive therapeutic targets in PDAC.

scholarly journals Synthesis, Quantification, and Characterization of Fatty Acid Amides from In Vitro and In Vivo Sources

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2543
Author(s):  
Ruidong Ni ◽  
Suzeeta Bhandari ◽  
Perry R. Mitchell ◽  
Gabriela Suarez ◽  
Neel B. Patel ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Fatty Acid ◽  
Apis Mellifera ◽  
Chemical Synthesis ◽  
Acid Amide ◽  
Fatty Acid Amides ◽  
Fatty Acid Amide

Fatty acid amides are a diverse family of underappreciated, biologically occurring lipids. Herein, the methods for the chemical synthesis and subsequent characterization of specific members of the fatty acid amide family are described. The synthetically prepared fatty acid amides and those obtained commercially are used as standards for the characterization and quantification of the fatty acid amides produced by biological systems, a fatty acid amidome. The fatty acid amidomes from mouse N18TG2 cells, sheep choroid plexus cells, Drosophila melanogaster, Bombyx mori, Apis mellifera, and Tribolium castaneum are presented.

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