The requirement for bivalent cations in formation of nicotinamide–adenine dinucleotide by nicotinamide mononucleotide adenylyltransferase of pig-liver nuclei

1. The requirement for bivalent cations in catalysis of NAD formation from ATP and NMN in the presence of NMN adenylyltransferase of pig-liver nuclei was studied. Rates of NAD formation in the presence of the activating cations Cd(2+), Mn(2+), Mg(2+), Zn(2+), Co(2+) and Ni(2+) were approximately a linear function of heats of hydration of the corresponding ions. Ba(2+), Sr(2+), Ca(2+), Cu(2+) and Be(2+) did not activate the enzyme; Be(2+) inhibited the reaction in the presence of Mg(2+) and, to a greater extent, in the presence of Ni(2+). 2. Michaelis constants for NAD formation, measured in a coupled assay with NMN adenylyltransferase and alcohol dehydrogenase at pH8.0 and 25 degrees , in the presence of 3mm concentrations of the unvaried reactants, were 88+/-7mum-ATP, 42+/-4mum-NMN and 85+/-4mum-Mg(2+). The results at this pH and at pH7.5 were consistent with mechanisms in which Mg(2+)-ATP complex is a reactant and free ATP a competitive inhibitor. 3. Formation of nicotinamide-hypoxanthine dinucleotide from NMN and ITP in the presence of the transferase was also more rapid with Ni(2+) and Co(2+) than with Mg(2+).     

Plasma concentrations of amino acid and nicotinamide metabolites in rheumatoid arthritis – potential biomarkers of disease activity and drug treatment

This study aimed to evaluate changes in plasma amino acid and nicotinamide metabolites concentrations in rheumatoid arthritis (RA) in a search for potential biomarkers of the disease activity and the effect treatment. Analysis of plasma metabolite patterns with liquid chromatography/mass spectrometry revealed specific changes in RA as well as correlations with clinical parameters. Combined concentration parameter calculated as [aspartic acid]?+?[threonine]?+?[tryptophan]???[histidine]???[phenylalanine] offered the strongest correlation (p?<?0.001) with pain joint count, swollen joint count and DAS 28. Such analysis of amino acid and related metabolite pattern offers potential for diagnosis as well as for monitoring disease progression and therapy in RA.     

Nicotinate, quinolinate and nicotinamide as precursors in the biosynthesis of nicotinamide–adenine dinucleotide in barley

1. The relative efficiencies of nicotinate, quinolinate and nicotinamide as precursors of NAD(+) were measured in the first leaf of barley seedlings. 2. In small amounts, both [(14)C]nicotinate and [(14)C]quinolinate were quickly and efficiently incorporated into NAD(+) and some evidence is presented suggesting that NAD(+) is formed from each via nicotinic acid mononucleotide and deamido-NAD. 3. [(14)C]Nicotinamide served equally well as a precursor of NAD(+) and although significant amounts of [(14)C]NMN were detected, most of the [(14)C]NAD(+) was derived from nicotinate intermediates formed by deamination of [(14)C]nicotinamide. 4. Radioactive NMN was also a product of the metabolism of [(14)C]nicotinate and [(14)C]quinolinate but most probably it arose from the breakdown of [(14)C]NAD(+). 5. In barley leaves where the concentration of NAD(+) is markedly increased by infection with Erysiphe graminis, the pathways of NAD(+) biosynthesis did not appear to be altered after infection. A comparison of the rates of [(14)C]NAD(+) formation in infected and non-infected leaves indicated that the increase in NAD(+) content was not due to an increased rate of synthesis.     

Occurrence and metabolism of 1′,4′-trans-diol of abscisic acid

The 1′,4′-trans-diol of abscisic acid was first identified in higher plants with GC-ECD and GC-SIM. The ²H-labelled derivative was converted into abscisic acid (ABA) in pea and avocado, but ²H-labelled ABA was not converted into the diol. These results suggest that the diol is one of the precursors of ABA in higher plants.     

Effects of capric acid on rumen methanogenesis and biohydrogenation of linoleic and α-linolenic acid

Capric acid (C10:0), a medium chain fatty acid, was evaluated for its anti-methanogenic activity and its potential to modify the rumen biohydrogenation of linoleic (C18:2n-6) and α-linolenic acids (C18:3n-3). A standard dairy concentrate (0.5 g), supplemented with sunflower oil (10 mg) and linseed oil (10 mg) and increasing doses of capric acid (0, 10, 20 and 30 mg), was incubated with mixed rumen contents and buffer (1 : 4 v/v) for 24 h. The methane inhibitory effect of capric acid was more pronounced at the highest (30 mg) dose compared to the medium (20 mg) (-85% v. -34%), whereas the lower dose (10 mg) did not reduce rumen methanogenesis. A 23% decrease in total short-chain fatty acid (SCFA) production was observed, accompanied by shifts towards increased butyrate at 20 mg and increased propionate at 30 mg of capric acid (P < 0.001). Capric acid linearly decreased the extent of biohydrogenation of C18:2n-6 and C18:3n-3, by up to 60% and 86%, respectively. This reduction was partially due to a lower extent of lipolysis when capric acid was supplemented. Capric acid at 20 and 30 mg completely inhibited the production of C18:0 (P < 0.001), resulting in an accumulation of biohydrogenation intermediates, mainly C18:1t10 + t11 and C18:2t11c15. In contrast to effects on rumen fermentation (methane production and proportions of SCFA), 30 mg of capric acid did not induce major changes in rumen biohydrogenation as compared to the medium (20 mg) dose. This study revealed the dual action of capric acid, being inhibitory to both methane production and biohydrogenation of C18:2n-6 and C18:3n-3.     

The activities of nicotinamide mononucleotied adenylyltransferase and of nicotinamide–adenine dinucleotide kinase in the livers of rats subjected to different hormonal treatments

1. The activities of NMN adenylyltransferase and of NAD(+) kinase have been measured in the livers of adrenalectomized or alloxan-diabetic rats and in the livers of rats treated with glucagon, pituitary growth hormone or thyroxine. 2. The activities of these enzymes have been compared with the effects of the same treatments on the nicotinamide nucleotide concentrations in the liver. 3. Alloxandiabetes (+37%) and thyroxine (+27%) both increased the activity of NMN adenylyltransferase. The other treatments were without effect on this enzyme. 4. Only thyroxine increased the activity of NAD(+) kinase significantly (+26%) although both adrenalectomy and glucagon tended to increase its activity. 5. The activity of NAD(+) glycohydrolase was measured in the livers of diabetic rats, and in the livers of rats treated with either growth hormone or thyroxine. Of these treatments, only growth hormone altered the enzyme activity (+26%, calculated on a total hepatic activity basis). 6. Female rats had a greater hepatic NAD(+)-kinase activity than males but there was no sex difference with respect to NMN adenylyltransferase. 7. The lack of correlation between the maximum potential activity of these three enzymes and the known changes of the nicotinamide nucleotides in each of the hormone conditions is discussed.     

Properties and regulation of leaf nicotinamide–adenine dinucleotide phosphate–malate dehydrogenase and `malic'' enzyme in plants with the C4-dicarboxylic acid pathway of photosynthesis

1. NADP-malate dehydrogenase and ;malic' enzyme in maize leaf extracts were separated from NAD-malate dehydrogenase and their properties were examined. 2. The NADP-malate dehydrogenase was nicotinamide nucleotide-specific but otherwise catalysed a reaction comparable with that with the NAD-specific enzyme. By contrast with the latter enzyme, a thiol was absolutely essential for maintaining the activity of the NADP-malate dehydrogenase, and the initial velocity in the direction of malate formation, relative to the reverse direction, was faster. 3. For the ;malic' enzyme reaction the K(m) for malate was dependent on pH and the pH optimum varied with the malate concentration. At their respective optimum concentrations the maximum velocity for this enzyme was higher with Mg(2+) than with Mn(2+). 4. The NADP-malate dehydrogenase in green leaves was rapidly inactivated in the dark and was reactivated when plants were illuminated. Reactivation of the enzyme extracted from darkened leaves was achieved simply by adding a thiol compound. 5. The activity of both enzymes was low in etiolated leaves of maize plants grown in the dark but increased 10-20-fold, together with chlorophyll, when leaves were illuminated. 6. The activity of these enzymes in different species with the C(4)-dicarboxylic acid pathway was compared and their possible role in photosynthesis was considered.     

Quantitative analysis and comparative decarboxylation of aminomalonic acid, β-carboxyaspartic acid,and γ-carboxyglutamic acid

Methods for quantitative analysis of the carboxylated amino acids, aminomalonic acid, β-carboxyaspartic acid, and γ-carboxyglutamic acid, are presented. These substances are acid labile and thus can be measured only after alkaline hydrolysis of proteins and peptides. Half-times for decarboxylation in 1 m HCl at 100°C are: aminomalonic acid (1.2 min); β-carboxyaspartic acid (1.7 min); and γ-carboxyglutamic acid (8.6 min). This property is useful for unequivocal identification in complex hydrolysates.     

Relationship between transport and metabolism of α-naphthaleneacetic acid, β-naphthaleneacetic acid and α-decalylacetic acid in segments of Coleus

Summary Transportand metabolism of -naphthaleneacetic acid -naphthaleneacetic acid, and -decalylacetic acid, all labelled with ¹⁴C in the carboxyl, group, were studied. Only -naphthaleneacetic acid is transported in a polar way. Most of the radioactivity in the tissue is in a low molecular form, either free or as immobilization products. The immobilization of -naphthaleneacetic acid is similar to that of -naphthaleneacetic acid. Immobilization of -decalylacetic acid is typically different. Bioassays showed -naphthaleneacetic acid as the sole biologically active component. It is concluded that stereo requirements necessary for biological activity are also required for polar auxin transport. It is further concluded that the observed specificity of the transport system is not related to the formation of immobilization products.     

Involvement of sialic acid in the regulation of γ--aminobutyric acid uptake activity of γ-aminobutyric acid transporter 1

The γ-aminobutyric acid (GABA) transporters (GATs) have long been recognized for their key role in the uptake of neurotransmitters. The GAT1 belongs to the family of Na(+)- and Cl(-)-coupled transport proteins, which possess 12 putative transmembrane (TM) domains and three N-glycosylation sites on the extracellular loop between TM domains 3 and 4. Previously, we demonstrated that terminal trimming of N-glycans is important for the GABA uptake activity of GAT1. In this work, we examined the effect of deficiency, removal or oxidation of surface sialic acid residues on GABA uptake activity to investigate their role in the GABA uptake of GAT1. We found that the reduced concentration of sialic acid on N-glycans was paralleled by a decreased GABA uptake activity of GAT1 in Chinese hamster ovary (CHO) Lec3 cells (mutant defective in sialic acid biosynthesis) in comparison to CHO cells. Likewise, either enzymatic removal or chemical oxidation of terminal sialic acids using sialidase or sodium periodate, respectively, resulted in a strong reduction in GAT1 activity. Kinetic analysis revealed that deficiency, removal or oxidation of terminal sialic acids did not affect the K(m) GABA values. However, deficiency and removal of terminal sialic acids of GAT1 reduced the V(max) GABA values with a reduced apparent affinity for extracellular Na(+). Oxidation of cell surface sialic acids also strongly reduced V(max) without affecting both affinities of GAT1 for GABA and Na(+), respectively. These results demonstrated for the first time that the terminal sialic acid of N-linked oligosaccharides of GAT1 plays a crucial role in the GABA transport process.     

Structure–activity relationship investigation of tertiary amine derivatives of cinnamic acid as acetylcholinesterase and butyrylcholinesterase inhibitors: compared with that of phenylpropionic acid,sorbic acid and hexanoic acid

In the present investigation, 48 new tertiary amine derivatives of cinnamic acid, phenylpropionic acid, sorbic acid and hexanoic acid (4d–6g, 10d–12g, 16d–18g and 22d–24g) were designed, synthesized and evaluated for the effect on AChE and BChE in vitro. The results revealed that the alteration of aminoalkyl types and substituted positions markedly influences the effects in inhibiting AChE. Almost of all cinnamic acid derivatives had the most potent inhibitory activity than that of other acid derivatives with the same aminoalkyl side chain. Unsaturated bond and benzene ring in cinnamic acid scaffold seems important for the inhibitory activity against AChE. Among them, compound 6g revealed the most potent AChE inhibitory activity (IC₅₀ value: 3.64?µmol/L) and highest selectivity over BChE (ratio: 28.6). Enzyme kinetic study showed that it present a mixed-type inhibition against AChE. The molecular docking study suggested that it can bind with the catalytic site and peripheral site of AChE.     

Relation between the oxidation state of nicotinamide–adenine dinucleotide and the metabolism of spermatozoa

1. The existing procedures for extraction of oxidized and reduced nicotinamide coenzymes were adapted to spermatozoa to overcome the coenzyme-degrading activity of seminal plasma. 2. The content of total NAD(+) and NADH was determined in the spermatozoa of ram, bull, boar, stallion and cock. NADP(+) and NADPH were not detected in ram spermatozoa. 3. The oxidation state of sperm NAD depended on the seminal plasma, the removal of which produced a change in the percentage oxidation state of the coenzyme, 100x[NAD(+)/(NAD(+)+NADH)], without altering the total content of NAD(+)+NADH. 4. In suspensions of washed ram spermatozoa, incubated anaerobically at 25 degrees C, the percentage oxidation state of NAD declined with increasing spermatozoa concentration. 5. When ram or boar spermatozoa that had been previously washed and resuspended in Ringer phosphate medium, were incubated anaerobically at 25 degrees C with various substances, pronounced effects on the percentage oxidation state of NAD could be observed with l-lactate, pyruvate, oxaloacetate, dihydroxyacetone, formaldehyde and glyceraldehyde; sorbitol and acetoacetate acted only on ram spermatozoa; fructose, glucose, mannose and acetaldehyde acted predominantly on boar spermatozoa. Formaldehyde lowered the (NAD(+)+NADH) content of ram spermatozoa, but none of the other substances had a comparable effect. 6. The percentage oxidation state of sperm NAD was not influenced by exogenous cysteine, cystine, ergothioneine or ascorbate. 7. A highly active sorbitol dehydrogenase could be prepared from ram, but not from boar, spermatozoa. 8. Sorbitol, acetoacetate and 3-hydroxybutyrate effectively supported the respiration of ram, but not boar, spermatozoa. 9. ;Cold shock', resulting from sudden cooling of spermatozoa, abolished motility completely and irreversibly but produced only a slow and partial decrease in the total NAD content. Slight over-heating, sufficient to produce loss of motility, had no adverse effect on the total NAD content. 10. Storage of ram sperm at 14 degrees C produced only a small decrease of NAD after 2 days, but subsequently the loss became greater.     

One-pot synthesis of bioactive cyclopentenones from α-linolenic acid and docosahexaenoic acid

Oxidation products of the poly-unsaturated fatty acids (PUFAs) arachidonic acid, α-linolenic acid and docosahexaenoic acid are bioactive in plants and animals as shown for the cyclopentenones prostaglandin 15d-PGJ₂ and PGA₂, cis-(+)-12-oxophytodienoic acid (12-OPDA), and 14-A-4 neuroprostane. In this study an inexpensive and simple enzymatic multi-step one-pot synthesis is presented for 12-OPDA, which is derived from α-linolenic acid, and the analogous docosahexaenoic acid (DHA)-derived cyclopentenone [(4Z,7Z,10Z)-12-[[-(1S,5S)-4-oxo-5-(2Z)-pent-2-en-1yl]-cyclopent-2-en-1yl] dodeca-4,7,10-trienoic acid, OCPD]. The three enzymes utilized in this multi-step cascade were crude soybean lipoxygenase or a recombinant lipoxygenase, allene oxide synthase and allene oxide cyclase from Arabidopsis thaliana. The DHA-derived 12-OPDA analog OCPD is predicted to have medicinal potential and signaling properties in planta. With OCPD in hand, it is shown that this compound interacts with chloroplast cyclophilin 20-3 and can be metabolized by 12-oxophytodienoic acid reductase (OPR3) which is an enzyme relevant for substrate bioactivity modulation in planta.     

Effects of 2α-DHET and its optical isomers on muscarinic and nicotinic receptors

The agent 2α-(2′, 2′-disubstituted-2′-hydroxy-ethoxy) tropane (2α-DHET), its optical isomers and atropine were compared in their ability to inhibit specific [³H]QNB binding to muscarinic receptors of guinea pig ileum and to antagonize oxotremorine- and nicotine—induced contractions of isolated guinea pig ileum. A good correlation was observed between the affinities to muscarinic receptors and the antimuscarinic potencies in isolated guinea pig ileum. The binding data for 2α-DHET and its isomers were also consistent with their central and peripheral pharmacological activity in vivo. Compounds with 2′R configuration are more suitable to the stereostruture of the binding sites of muscarinic receptors than that of 2′S configuration.     

Upregulation of UGT1A1 expression by ursolic acid and oleanolic acid via the inhibition of the PKC/NF-κB signaling pathway

BackgroundIsomeric ursolic acid (UA) and oleanolic acid (OA) compounds have recently garnered great attention due to their biological effects. Previously, it had been shown that UA and OA can exert important pharmacological action via the protein kinase C (PKC) and nuclear factor-κB (NF-κB) signaling, and that they can induce the expression of UDP-glucuronosyltransferase 1A1 (UGT1A1) in HepG2 cells. This study aims to investigate the role of PKC/NF-κB signaling in regulating the expression of UGT1A1 and examine how UA and OA induce UGT1A1 based on this signaling pathway.MethodsHepG2 cells, hp65-overexpressed HepG2 cell and lentivirus-hp65-shRNA silenced HepG2 cells were stimulated with PKC/NF-κB specific agonists and inhibitors for 24 h in the presence or absence of UA and OA. The expression of UGT1A1, PKC, and NF-κB were determined by qRT-PCR, western blot, and dual-luciferase reporter gene assays.ResultsPKC/NF-κB activation downregulates UGT1A1 expression. This effect is countered by UA and OA treatment. Phorbol 12-myristate 13-acetate (PMA) and lipopolysaccharide (LPS), the agonists of PKC and NF-κB signaling, respectively, significantly inhibit hp65-mediated UGT1A1 luciferase activity. UA, OA, and the PKC/NF-κB inhibitors suppress this effect. PMA and LPS do not affect UGT1A1 activity in p65-silenced HepG2 cells; however, UA and OA mildly influence UGT1A1 expression in these cells.ConclusionThe activation of PKC/NF-κB signaling can significantly downregulate UGT1A1 expression. By inhibiting the PKC/NF-κB signaling pathway, UA and OA promote UGT1A1 expression in HepG2 cells.     

Eicosapentaenoic acid and docosahexaenoic acid reduce interleukin-1β-mediated cartilage degradation

Introduction  

In inflammatory joint disease, such as osteoarthritis (OA), there is an increased level of proinflammatory cytokines, such as interleukin (IL)-1β. These cytokines stimulate the production of matrix metalloproteinases (MMPs), which leads to the degradation of the cartilage extracellular matrix and the loss of key structural components such as sulphated glycosaminoglycan (sGAG) and collagen II. The aim of this study was to examine the therapeutic potential of n-3 polyunsaturated fatty acids (PUFAs) in an in vitro model of cartilage inflammation.     

The purification and properties of the respiratory-chain reduced nicotinamide–adenine dinucleotide dehydrogenase of Torulopsis utilis

1. An NADH-ferricyanide reductase activity has been isolated from the respiratory chain of Torulopsis utilis by using detergents. The isolated enzyme contains non-haem iron, acid-labile sulphide and FMN in the molar proportions 27.5:28.4:1. The preparation is free of FAD and largely free of cytochrome. 2. The enzyme catalyses ferricyanide reduction by NADPH at about 1% of the rate with NADH, and reacts poorly with acceptors other than ferricyanide. The rates of reduction of some acceptors are, as percentages of the rate with ferricyanide: menadione, 0.35%; lipoate, 0.01%; cytochrome c, 0.065%; dichlorophenolindophenol, 0.35%; ubiquinone-1, 0.08%. 3. Several properties of submitochondrial particles of T. utilis (non-haem iron, acid-labile sulphide, FMN and an NADH-reducible electron-paramagnetic-resonance signal) were found to co-purify with the NADH-ferricyanide reductase activity. Thus about 70% of the FMN and, within the limits of accuracy of the experiments, 100% of the non-haem iron and acid-labile sulphide of submitochondrial particles derived from T. utilis cells grown under conditions of glycerol limitation (but relatively low iron availability) can be attributed to the NADH-ferricyanide reductase. 4. It was also shown that the component of submitochondrial particles specifically bleached at 460nm by NADH [species 1 of Ragan & Garland (1971)] co-purifies with the NADH-ferricyanide reductase. 5. This successful purification of an NADH dehydrogenase from T. utilis forms a starting point for investigating the molecular properties of phenotypically modified mitochondrial NADH oxidation pathways that lack energy conservation between NADH and the cytochromes.