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PubMedDate not supplied

Induction of hydroxycinnamic acid amides and tryptophan by jasmonic acid, abscisic acid and osmotic stress in barley leaves.

The effects of jasmonic acid (JA) and abscisic aid (ABA) on secondary metabolism in barley (Hordeum vulgare L.) were investigated. Treatment with JA at 100 microM for 48 h induced accumulation of four compounds in barley primary leaves. The accumulation of these compounds was also observed after treatment with ABA at 100 microM. The induced compounds were identified as p-coumaroylputrescine, p-coumaroylagmatine, p-coumaroyl-3-hydroxyagmatine and tryptophan by spectroscopic methods. The profiles of compounds induced by application of JA and ABA were different. JA exhibited stronger inducing activity for hydroxycinnamic acid amides than ABA, while ABA was more active in tryptophan accumulation. The major hydroxycinnamic acid amides in JA- and ABA-treated leaves were p-coumaroylagmatine and p-coumaroyl-3-hydroxyagmatine, respectively. These differences suggested that JA and ABA act in distinct modes. The induction of these compounds was also observed in leaf segments treated with 1 M sorbitol and glucose. These findings suggested that JA and ABA are involved in accumulation of hydroxycinnamic acid amides and tryptophan in response to osmotic stress in barley.

Abscisic Acid↗

PubMed2006

Conformational effects in enzyme catalysis: reaction via a high energy conformation in fatty acid amide hydrolase.

Quantum mechanics/molecular mechanics and molecular dynamics simulations of fatty acid amide hydrolase show that reaction (amide hydrolysis) occurs via a distinct, high energy conformation. This unusual finding has important implications for fatty acid amide hydrolase, a key enzyme in the endocannabinoid system. These results demonstrate the importance of structural fluctuations and the need to include them in the modeling of enzyme reactions. They also show that approaches based simply on studying enzyme-substrate complexes can be misleading for understanding biochemical reactivity.

Amidohydrolases↗

PubMed1988

Effects of dietary sodium restriction on peptide stimulation of aldosterone secretion by the isolated perfused rat adrenal gland in situ: a report of exceptional sensitivity to angiotensin II amide.

The effects of prior sodium depletion on the steroidogenic responses of the rat adrenal gland have been investigated using a method of perfusing the isolated adrenal gland of the rat in situ. Secretion rates of aldosterone in response to the known adrenocortical stimulants ACTH, angiotensin II amide and alpha-MSH were measured. In each case, the adrenals from sodium-deplete animals responded to a lower dose of the stimulant than the normal animals. This resulted in a 10-fold increase in sensitivity to ACTH, a 100-fold increase in sensitivity to angiotensin II amide, and a 1000-fold increased sensitivity to alpha-MSH, bringing the threshold concentration required for aldosterone secretion into the physiological range of alpha-MSH concentrations. The perfused adrenal gland is particularly sensitive to angiotensin II amide; a bolus administration of 1 amol gave a significant increase in aldosterone secretion in the sodium-deplete group. These data confirm previous reports of increased adrenal sensitivity to alpha-MSH and angiotensin II in sodium depletion, and also suggest the existence of intraglandular mechanisms for signal amplification which may be involved in mediating the adrenal response to very small concentrations of stimulant.

Adrenal Glands↗

PubMedDate not supplied

Determination of the lipophilicity of active anticonvulsant N-substituted amides of alpha-arylalkylamine-gamma-hydroxybutyric acid.

The lipophilicities of fourteen anticonvulsant active N-substituted amides of alpha-arylalkylamine-gamma-hydroxybutyric acid [I-XIV] have been determined by reversed-phase thin-layer chromatography with a mixture of methanol, TRIS buffer, and acetic acid as the solvent system. The RM value of each compound decreased linearly with increasing concentration of methanol. The partition coefficients (log P) of the amides were calculated by use of the Prolog P module of the Pallas system. Comparison of RM and log P enabled clog P values to be calculated. It was found that the anticonvulsant activity of amides [I-XIV] can be explained on the basis of their lipophilicity.

Amides↗

PubMed1999

[The influence of steric crowding on the electrochemical reduction of amide groups in a pyridylcarboxamide seriesapplication to rote ction of amines in peptide synthesis].

To gain a better understanding of the effect exerted by the 3-hydroxypicolinoyl residue on the antibiotic activity of Pristinamycin IA, the C-N bond of picolinamide was cleaved electrochemically. A mechanistic study demonstrated that the presence of the peptidic macrolactone M markedly modified the expected cathodic behavior of pyridylcarboxamides. In order to assess the influence of steric crowding exerted by M on this original behavior, we look for models using two different approachs. First, tertiary pyridylcarboxamides were used to increase steric hindrance at the amide nitrogen position; second, M was opened by ammonolysis to decrease steric crowding at the amide nitrogen position. The electrochemical behavior of the selected compounds is presented in the first and the second parts of this study. Determination of pyridine nitrogen basicity in an N-substituted-3-methoxypicolinamide series is treated in the third part as a useful probe to evaluate the intensity of steric crowding at the amide nitrogen position. Finally, in the last part of this work, we propose the use of the picolinoyl residue (C6H4N-CO-ou Pic) as a protecting group for amines in peptide synthesis.

Amides↗

PubMed2000

Subcellular organization of bile acid amidation in human liver: a key issue in regulating the biosynthesis of bile salts.

To extend our knowledge of how the synthesis of free bile acids and bile salts is regulated within the hepatocyte, bile acid-CoA:amino acid N-acyltransferase and bile acid-CoA thioesterase activities were measured in subcellular fractions of human liver homogenates. Some bile acids, both conjugated and unconjugated, have been reported to be natural ligands for the farnesoid X receptor (FXR), an orphan nuclear receptor. The conversion of [(14)C]choloyl-CoA and [(14)C]chenodeoxycholoyl-CoA into the corresponding tauro- and glyco-bile acids or the free bile acids was measured after high-pressure liquid radiochromatography. There was an enrichment of the N-acyltransferase in the cytosolic and the peroxisomal fraction. Bile acid-CoA thioesterase activities were enriched in the cytosolic, peroxisomal, and mitochondrial fractions. The highest amidation activities of both choloyl-CoA and chenodeoxycholoyl-CoA were found in the peroxisomal fraction (15-58 nmol/mg protein/min). The K(m) was higher for glycine than taurine both in cytosol and the peroxisomal fraction.These results show that the peroxisomal de novo synthesis of bile acids is rate limiting for peroxisomal amidation, and the microsomal bile acid-CoA synthetase is rate limiting for the cytosolic amidation. The peroxisomal location may explain the predominance of glyco-bile acids in human bile. Both a cytosolic and a peroxisomal bile acid-CoA thioesterase may influence the intracellular levels of free and conjugated bile acids.

Acyltransferases↗

PubMedDate not supplied

[Effects of nitriles and amides on the growth and the nitrile hydratase activity of the Rhodococcus sp. strain gt1].

Effects of some nitriles and amides, as well as glucose and ammonium, on the growth and the nitrile hydratase (EC 4.2.1.84) activity of the Rhodococcus sp. strain gt1 isolated from soil were studied. The activity of nitrile hydratase mainly depended on carbon and nitrogen supply to cells. The activity of nitrile hydratase was high in the presence of glucose and ammonium at medium concentrations and decreased at concentrations of glucose more than 0.3%. Saturated unsubstituted aliphatic nitriles and amides were found to be a good source of nitrogen and carbon. However, the presence of nitriles and amides in the medium was not absolutely necessary for the expression of the activity of nitrile hydratase isolated from the Rhodococcus sp. strain gt1.

Amides↗

PubMedDate not supplied

Synthesis and disulfide structure determination of agelenin: identification of the carboxy-terminus as an amide form.

Agelenin, a blocker of the presynaptic calcium channel, is a 35-amino acid peptide having six cysteinyl residues recently isolated from the venom of the spider Agelena opulenta. However, it has not been confirmed whether the carboxy-terminus of this peptide is a free acid or amide. To elucidate this, we synthesized both peptides by a solid phase procedure, and compared their elution profiles with that of the natural product on RP-HPLC. The retention time on HPLC as well as the biological activity of the synthetic peptide-amide was found to be identical with those of natural agelenin, confirming that the carboxy-terminus of agelenin is amidated. The disulfide structure of agelenin was also determined to be linked between 3-19, 10-24 and 18-34, by comparing the tryptic peptide linked by two disulfide bonds with those synthesized by the selective formation of disulfide bonds.

Amides↗

PubMedDate not supplied

Synthesis, physicochemical and anticonvulsant properties of some n-substituted amides of 3-spirocycloalkylpyrrolidine-2,5-dione.

The synthesis and physicochemical properties of new derivatives of N-benzyl and N-phenyl amides of 2-(3-spirocyclohexanepyrrolidine-2,5-dione) acetic acid. 4-(3-spirocyclohexanepyrrolidine-2,5-dione) benzoic acid and 4-(3-spirocyclopentanepyrrolidine-2,5-dione) benzoic acid are described. N-substituted amides were prepared by condensing the obtained acids with the corresponding phenyl- or benzylamine derivatives in DMF, in the presence of the N,N-carbonyldiimidazol (CDIM) reagent at room temperature. The compounds were evaluated for anticonvulsant activity. The portion coefficients were calculated using the Prolog P module of the Pallas system. The structure of the new amides was confirmed by elemental and spectral analyses.

Amides↗

PubMedDate not supplied

[Effect of carbohydrates and polyols on amide content and protein fragmentation in a lactoglobulin preparation].

Certain carbohydrates and polyols are used at various stages of the production of immunobiological preparations as stabilizers of biological activity, particularly in the production of lactoglobulin (against opportunistic pathogens) using membrane ultrafiltration. This study concerns the effect of these substances on changes in the amide content in proteins of this lactoglobulin. Lactoglobulin was incubated in near-physiological (0.9% NaCl, pH 5.5) 10% solutions of glucose, fructose, and sorbitol at 4 and 35 degrees C for 7, 14, and 28 days. A lactoglobulin solution in 0.9% NaCl, pH 5.5, was used as the control. All substances studied suppressed the reduction of the amide group content of asparagine and, in contrast, increased the rate of amide group removal from glutamine residues in proteins of lactoglobulin preparations.

Amides↗

PubMed1991

Biochemical studies on sulfated lactobionic acid amides.

A series of sulfated bis-lactobionic acid amides was prepared. The compounds comprise highly charged poly-anions of very low molecular weight. Usually, the compounds contain 16 sulfate groups per molecule and are homogeneous, monodisperse substances. The molecular weights range from 2388 to 2514. The compounds were evaluated for anticoagulant activity using a number of standard tests. The compounds exhibited moderate to good APTT activity. Interestingly, the anti-Xa and anti-IIa activities were very low, particularly in amidolytic assays. Using prothrombin and Factor X activation assays, it was demonstrated that these compounds were more potent in these experimental settings than in standard anti-Xa or anti-IIa assays. Compared with heparin and LMW heparins, the bis-lactobionic acid amides were particularly active as inhibitors of the intrinsic system activation of Factor X. The bis-lactobionic acid amides exhibited potent anticomplement activity, being clearly superior to heparin and LMW heparins. For the most interesting substance, LW 10082, experimental results suggest that its anticoagulant activity is independent of antithrombin II. The anticoagulant activity of LW 10082 was readily neutralized by protamine sulfate. Platelet factor 4, however, did not reduce its anticoagulant activity. Because of these favorable properties, it is hoped that LW 10082 might prove to be an interesting alternative to heparin or LMW heparin in clinical use.

Amides↗

PubMed1991

Antithrombotic and anticoagulant properties of synthetic polyanions: sulfated bis-aldonic acid amides.

Fifteen polyanionic bis-aldonic acid amides were synthesized by condensation of the corresponding aldonic acids and alpha,omega-diamines and by subsequent sulfation of the intermediates. The compounds were completely sulfated and exhibited molecular weights between 1450 and 2600 daltons. The antithrombotic activity of these synthetic heparin analogs was evaluated in a rat jugular vein clamping induced thrombosis model. Several compounds pounds were potent antithrombotic substances comparable in potency to the low molecular weight heparin Fraxiparin. Some structure activity relationships on their pharmacologic action could be deduced. The antithrombotic activity of a representative agent was confirmed using the Wessler stasis model in rabbits. In the in vitro tests the bis-aldonic acid amides exhibited moderate to low anticoagulant effects depending on the assay used. In the activated partial thromboplastin time assay, the anticoagulant potency of these compounds was between 2- and 30-fold lower than that of heparin. The anti-factor Xa activity of the experimental substances was at least 50 times lower than that of heparin, whereas the compounds were devoid of anti-factor IIa activity when measured in an amidolytic assay. The anticoagulant effects of these agents were dependent on the length of the spacing and on the type of aldonic acid moieties. These bisaldonic acid amides represent a novel class of potent antithrombotic substances without any anti-factor IIa activities and only very low anti-factor Xa activities, suggesting that these antiprotease actions are not a prerequisite for the antithrombotic action of polyanionic substances.

Amides↗

PubMed2006

Emerging methods in amide- and peptide-bond formation.

Amide bonds are the key chemical connections in proteins and peptides and have a long-established presence in small-molecule therapeutics. Despite their recognized importance, amide bond synthesis relies almost solely on variants of a single reaction: the dehydrative coupling of carboxylic acids and amines. While phenomenally successful in many applications, this process requires superstoichiometric quantities of expensive reagents and precludes chemoselective ligation reactions. This review summarizes emerging chemical alternatives to amide-bond formation with particular emphasis on the development of ligation reactions that permit the coupling of unprotected peptide fragments.

Amides↗

PubMed1991

Pharmacologic profile of the antithrombotic and bleeding actions of sulfated lactobionic acid amides.

1. The introduced bis-lactobionic acid amides represent a new group of synthetic polyanions with a molecular weight of 2387 to 2514d. The compounds are homogeneous and chemically defined. 2. The in vitro blood coagulation parameters (APTT, Heptest, anti-Xa, thrombin time, and anti-IIa) are only marginally altered by these compounds. 3. In a rat model of venous thrombosis using endothelial damage as the thrombogenic stimulus, the antithrombotic activity of the bis-lactobionic acid amides was shown in a dose- and time-dependent manner. 4. LW 10082 and LW 10121 prolong the bleeding time at dosages about 10 times less than that of heparin. The safety/efficacy index appears to be wider for these compounds than for heparin. 5. In subchronic toxicologic studies in rats, LW 10082 was well tolerated up to a dosage of 100 mg/kg body weight. 6. The anticoagulant and antithrombotic activities of the bis-lactobionic acid amides decrease gradually with the increasing number of methylene groups in the alkylene chain.

Amides↗

PubMed1990

Kinetic deuterium isotope effects on the N-demethylation of tertiary amides by cytochrome P-450.

Liver microsomal cytochrome P-450 readily N-dealkylates N,N-dimethylamides. N-Methyl-N-hydroxymethyl amides were isolated as intermediates and characterized by gas chromatography-mass spectrometry as their trimethylsilyl ethers. Intramolecular kinetic deuterium isotope effects measured for the enzymic N-demethylation of a series of 12 aromatic and aliphatic N-methyl-N-trideuteriomethyl amides, RCON(CH3)CD3, varied from 3.6 to 6.9 but were independent of both amide bond rotation rate and substrate oxidation potential. These values, which represent a lower limit to the intrinsic isotope effect (Dkintrinsic), are significantly larger than those observed for anodic N-demethylation and are consistent with a mechanism involving hydrogen atom abstraction. On the other hand, with N,N-dimethylbenzamide the intermolecular kinetic deuterium isotope effects on Vmax and Vmax/Km were found to be much smaller (1.23 and 1.75, respectively) indicating substantial suppression of the intrinsic isotope effect. Such suppression indicates the occurrence of a rate-limiting step other than the isotopically sensitive step together with a strong commitment to catalysis.

Amides↗

PubMed1989

Morphine-like activity of substituted amides & imides of [D-Ala2, Met5]-enkephalin.

Six enkephalin analogues (N-substituted amides and imides of [D-Ala2, Met5]-enkephalin) were synthesized and tested for opioid activity. All the compounds, except one i.e., compound IV, showed analgesic activity which was much higher than Met-enkephalin and morphine in mice and inhibited electrically induced contractions of isolated guineapig ileum, [D-Ala2, Met5]-enkephalin-morpholide and [D-Ala2, Met5]-enkephalin-beta-Ala-amide were the most potent analgesics and nearly 6 and 500 times as active as morphine and Met-enkephalin respectively. Both the compounds were equipotent on the guineapig ileum preparation, whereas the beta-Ala-amide was about twice as active as the morpholide in the electrically stimulated mouse vas deferens preparation.

Amides↗

PubMed1978

Specific modification of the properties of the N-hydroxylase. Relationship with carcinogenesis by aromatic amides.

N-hydroxylation represents the first and limiting step in the metabolic pathway leading to the carcinogenic activity of aromatic amines and amides. Using a method recently developed by the same authors (Analytical Biochemistry, in press), the effects of pretreatment of male adult rats with N-2-acetylaminofluorene (2AAF), N-4-acetylaminofluorene (4AAF), N-4-acetyl-aminobiphenyl, (4-AABP), and phenobarbital (PB), on the kinetic parameters of the N-hydroxylase activity have been evaluated and compared. Our resutls clearly demonstrate that both hepatocarcinogenic amides, 2-AAF and 4-AABP very significantly increase the affinity of the activating enzyme towards both substrates; on the other hand, 4-AAF and PB, which are non-carcinogenic compounds slightly decrease the affinity of the enzyme. In conclusion, the carcinogenic aromatic amides seem to specifically modify the catalytic properties of the enzyme responsible for their own metabolic activation.

2-Acetylaminofluorene↗

PubMed1989

The geometry of N-hydroxymethyl compounds. Part 3: Geometries of N-(hydroxymethyl)amides related to reactivities.

Using MNDO calculations, ground state structures of 11 N-(hydroxymethyl)amides were predicted to have pyramidal nitrogens and an s-Z conformation. The results compare favourably with ab initio calculations and with X-ray data except that MNDO tends to predict twist angles around partial double bonds which are too large. A correlation was found between N-CH2OH bond length and the logarithm of the half-life under physiological conditions. MNDO ground state structures for five N-(hydroxymethyl)amide anions were calculated to have s-E conformations and their N-CH2OH bond lengths also correlated with the half-lives of the N-(hydroxymethyl)amides. These correlations may be valuable in assessing potential anti-tumour activity.

Amides↗