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PubMed1991

Polyphosphate Hydrolysis within Acidic Vacuoles in Response to Amine-Induced Alkaline Stress in the Halotolerant Alga Dunaliella salina.

The location and mobilization of polyphosphates in response to an amine-induced alkaline stress were studied in the halotolerant alga Dunaliella salina. The following observations suggest that polyphosphates accumulate in acidic vacuoles: (a) Accumulation of large amounts of polyphosphates is manifested as intravacuolar dense osmiophilic bodies in electron micrographs. (b) Uptake of amines into the vacuoles induces massive hydrolysis of polyphosphates, demonstrated by in vivo(31)P-nuclear magnetic resonance, and by analysis of hydrolytic products on thin layer chromatograms. The analysis indicates that: (a) Polyphosphate hydrolysis is kinetically correlated with amine accumulation and with the recovery of cytoplasmic pH. (b) The major hydrolytic product is tripolyphosphate. (c) The peak position of the tripolyphosphate terminal phosphate in nuclear magnetic resonance spectra is progressively shifted as the cells recover, indicating that the pH inside the vacuoles increases while the pH in the cytoplasm decreases. (d) In lysed cell preparations, in which vacuoles become exposed to the external pH, mild alkalinization in the absence of amines induces polyphosphate hydrolysis to tripolyphosphates. It is suggested that amine accumulation within vacuoles activates a specific phosphatase, which hydrolyzes long-chain polyphosphates to tripolyphosphates. The hydrolysis increases the capacity of the vacuoles to sequester amines from the cytoplasm probably by releasing protons required to buffer the amine, and leads to recovery of cytoplasmic pH. Thus, polyphosphate hydrolysis provides a high-capacity buffering system that sustains amine compartmentation into vacuoles and protects cytoplasmic pH.

Journal Article↗
PubMed2005

Synthesis and pharmacological activities of amine-boranes.

A number of amine-boranes and related derivatives possess a wide range of biological activities including antineoplastic, antiviral, hypolipidemic, anti-inflammatory activities, anti-osteoporotic and dopamine receptor antagonist activities. The compounds include borane complexes of alpha-amino acids, aromatic, aliphatic and heterocyclic amines, and nucleosides. The syntheses of amine-borane derivatives are generally carried out by first preparing a tertiary amine- or phosphine-cyano- or carboxyborane to serve as a borane donor for a subsequent Lewis acid exchange reaction. Borane adducts of simple aliphatic amines, heterocyclic amines and nucleic acids demonstrated potent cytotoxic activity in vitro and in vivo against murine and human tumor models. These boron-containing compounds were shown to inhibit DNA synthesis; such inhibition was caused primarily by reducing de novo purine biosynthesis via inhibition of PRPP amidotransferase, IMP dehydrogenase and dihydrofolate reductase activities. Aliphatic, heterocyclic and nucleoside amine-boranes have also been shown to possess hypolipidemic activity in mice and rats. Many boron derivatives from different chemical classes demonstrated both cytotoxic and hypolipidemic activities. They decreased low-density lipoprotein (LDL) cholesterol while increasing high-density lipoprotein (HDL) cholesterol levels. The mode of action of these compounds in the 50-100 microM concentration range appeared to be by increasing lipid excretion from the body and by inhibiting rate-limiting enzyme activities for the de novo synthesis of lipids and cholesterol (e.g., phosphatidylate phosphohydrolase, ATP-dependent citrate lyase, cytoplasmic acetyl coenzyme A [CoA] synthetase, HMG CoA reductase, and acetyl CoA carboxylase). Selected amine-boranes (e.g., trimethylamine-cyanoborane, N-methylmorpholine-cyanoborane, and the base-boronated 2'-deoxynucleosides) have anti-inflammatory, analgesic, anti-arthritic and anti-osteoporotic activities.

Animals↗
PubMed1992

A substrate-cofactor free radical intermediate in the reaction mechanism of copper amine oxidase.

Reduction of copper amine oxidase with substrate led to the appearance of a free radical which can be detected in anaerobiosis by ESR and optical spectroscopy. The origin of this radical was examined through studies of the semiquinones of 6-hydroxydopamine, an analogue of the recently identified cofactor 6-hydroxydopa. The ESR spectrum of the 6-hydroxydopamine radical was too narrow to account for the enzyme radical signal; however, after spontaneous reaction with primary amines the hyperfine splittings and spectral width obtained by modulation broadening became very similar to those observed for the oxidase radical species. This effect was ascribed to covalent binding of a nitrogen atom directly to the aromatic ring structure, suggesting that the amine oxidase radical is an amino-6-hydroxydopa semiquinone. Identical ESR spectra were obtained using the amines putrescine, cadaverine, p-[(dimethylamino)methyl]benzylamine, and ethylenediamine; these oxidase substrates gave identical enzyme radical spectra as well. The interaction between cofactor and substrate was proved unambiguously by the technique of isotopic labeling: addition of [15N2]ethylenediamine instead of the normal 14N-labeled compound changed the ESR spectra of both the enzyme radical and its 6-hydroxydopamine counterpart. The results were confirmed by optical spectroscopy measurements; 6-hydroxydopamine and oxidized 6-hydroxydopamine gave spectra identical to those of reduced and oxidized amine oxidase, respectively. The 6-hydroxydopamine radical showed a sharp peak at 440 nm; upon addition of amines the maximum shifted to 460 nm, as found for the enzyme. It is proposed that copper amine oxidase represents the first example of a mixed substrate-cofactor radical within the family of tyrosine radical enzymes.

Amine Oxidase (Copper-Containing)↗
PubMed2006

Enantioselective organocatalytic reductive amination.

The first enantioselective organocatalytic reductive amination reaction has been accomplished. The development of a new chiral phosphoric acid catalyst has provided a convenient strategy for the enantioselective construction of protected primary amines and provided a highly stereoselective method for the reductive amination of heterocyclic amines. A diverse spectrum of ketone and amine substrates can be accommodated in high yield and excellent enantioselectivity. This new protocol realizes a key benefit of reductive amination versus imine reduction, in that ketimines derived from alkyl-alkyl ketones are unstable to isolation, a fundamental limitation that is comprehensively bypassed using this direct organocatalytic reductive amination.

Amination↗
PubMed1996

Comparison of kinetic properties between plant and fungal amine oxidases.

Kinetic properties of novel amine oxidases isolated from a mold Aspergillus niger AKU 3302 were compared to those of typical plant amine oxidase from pea seedling (EC 1.4.3.6). Pea amine oxidase showed highest affinity with diamines, such as putrescine and cadaverine, while fungal enzymes oxidized preferably n-hexylamine and tyramine. All enzymes were inhibited by carbonyl reagents, copper chelating agents, some substrate analogs and alkaloids, but there were quite significant differences in the sensitivity and inhibition modes. Aminoguanidine, which strongly inhibited pea amine oxidases showed only little effect on fungal enzymes. Substrate analogs such as 1.5-diamino-3-pentanone and 1-amino-3-phenyl-3-propanone, which were potent competitive inhibitors of pea amine oxidases, inhibited fungal enzymes much more weakly and non competitively. Also various alkaloids behaving as competitive inhibitors of pea amine oxidase inhibited the fungal enzymes non competitively. Very surprising was the potent inhibition of fungal enzymes by artificial substrates of pea amine oxidases, E- and Z-1,4-diamino-2-butene. The relationships between the different inhibition modes and possible binding at the active site are discussed.

Amine Oxidase (Copper-Containing)↗
PubMed1994

Comparative mutagenicity of plant-activated aromatic amines using Salmonella strains with different acetyltransferase activities.

Plant systems can activate aromatic amines into mutagens. In the plant cell/microbe coincubation assay, we earlier demonstrated that 2-aminofluorene and m-phenylenediamine were activated by plant cells into mutagens with reversion at the hisD3052 allele in Salmonella typhimurium strain TA98 as the genetic endpoint. New derivatives have been developed which possess elevated levels of acetyl-CoA:N-hydroxyarylamine O-acetyltransferase which are very sensitive to N-hydroxylated amines [Watanabe et al., 1990: Mutat Res 234:337-348]. The objectives of this research were to examine Salmonella strains with different acetyltransferase activities in the plant cell/microbe coincubation assay with a series of structurally related aromatic amines. The hypothesis tested was whether and to what degree a plant-activated metabolite of these aromatic amines could serve as a substrate for bacterial O-acetyltransferase and induce mutation in Salmonella. Every aromatic amine examined was activated by plant cells with YG1024 (the strain with elevated O-acetyltransferase activity) as the genetic indicator organism. The rank order of the mutagenic responses of YG1024 to the plant-activated aromatic amines was 2-aminofluorene > benzidine > m-phenylenediamine > 4-aminobiphenyl > 2,4-diaminotoluene > 2-naphthylamine. This rank order was expressed by TA98 but to a much lower degree. There was a very slight mutagenic response observed in TA98/1,8-DNP6 (a strain lacking O-acetyltransferase activity) with the plant-activated metabolites of benzidine and 4-aminobiphenyl. We conclude that the plant-activated aromatic amines are substrates for bacterial O-acetyltransferases.

2-Naphthylamine↗
PubMedDate not supplied

Sensory and pulmonary irritation of aliphatic amines in mice: a structure-activity relationship study.

The expiratory bradypnea indicative of upper airway irritation in mice was evaluated during a 15-min oronasal exposure to increasing concentrations of sixteen aliphatic amines. The airborne concentration resulting in a 50% decrease in the respiratory rate of mice (RD50) was calculated for each test compound. Moreover, the sixteen amines were tested for pulmonary irritation by measuring the decrease in respiratory rate of (non-anaesthetized) tracheally cannulated mice (RD50 TC). The RD50 and RD50 TC values and their ratios were related to n-octanol/water partition coefficients (log P). The RD50 values associated with exposure to saturated amines ranged from 17 to 300 ppm. The RD50TC values for these saturated amines ranged from 35 to 489 ppm. The RD50 and RD50TC values of saturated amines were closely related to the n-octanol/water partition coefficient, indicating that the more lipophilic amines are more irritant for the upper and lower respiratory tracts. The RD50TC/RD50 values were much less closely related to the n-octanol/water partition coefficient. Based on the results, tentative standards are suggested for the studied amines.

Administration, Inhalation↗
PubMed1992

Changes in brain amine levels associated with the morphological and behavioural development of the worker honeybee.

Changes in biogenic amine levels associated with the morphological and behavioural development of the worker honeybee are examined. A significant increase in amine levels in the head of the honeybee is associated with transition from the larval to pupal stage. Adult emergence is also accompanied by a significant increase in 5-HT levels in the brain, but no significant change in brain dopamine (DA) levels. NADA (N-acetyldopamine) levels increase during larval and pupal development, but in contrast to both DA and 5-HT, drop significantly during the transition from pupa to adult. Levels of DA in the brain of nectar and pollen forager bees, presumed to be among the oldest adults sampled, were found to be significantly higher than in nurses, undertakers or food storers. These results suggest that an age-dependent change in amine levels occurs in the brain of the worker bee. In the optic lobes, levels of DA and 5-HT were found to be significantly higher in pollen forager bees than in all other behavioural groups. Significant differences in amine levels in the optic lobes of nectar foragers and pollen foragers indicate that some differences in amine levels occur independent of worker age. The functional significance of differences in brain amine levels and whether or not biogenic amines play a direct role in the control of honeybee behaviour has yet to be established.

Aging↗
PubMed1977

Identification of two populations of biogenic amine-containg cells in the mouse lung.

Two distinct populations of fluorogenic amine-containing cells were observed in the lungs of nine-week old mice: one with an intense yellow emission, which possible indicates the presence of serotonin; and one emitting a yellow-green fluorescence, which probably indicates the presence of a catecholamine such as dopamine or norepinephrine. Simultaneous identification of two different fluorogenic amine-containing cells, without pre-administration of a precursor to that amine, has not previously been reported. Such evidence of amine-containing cells demonstrated the success of the perfusion-freezing technique and established that cellular storage of fluorogenic amines does occur in vivo under normal physiological conditions. The function of such amine-containing cells has not been established; however, their location and the known physiological effects of amines would suggest regional control of ventilation/perfusion of the lung.

Animals↗
PubMedDate not supplied

Cellular localization and metabolic function of n-butylamine-induced amine oxidases in the fungus Aspergillus niger AKU 3302.

Using transmission electron microscopy, the amine oxidase activity in Aspergillus niger AKU 3302 was localized to the outer side of the cell wall but not inside the cell using the cerium perhydroxide deposition method. The presence of cerium in the deposit was confirmed by energy-dispersive microanalysis of X-rays. Interestingly, immunocytochemical localization using gold labeling with a specific antibody indicated the presence of amine oxidase protein inside the cell wall and not only on the outer surface. Besides labeling of the cell wall, a high level of labeling was also observed inside the cell in what seemed to be secretory vesicle structures. It is proposed that the highly active amine oxidase AO-I is located in the cell wall and serves primarily as a detoxifying agent, preventing amines from entering and damaging the cell. The amine oxidation exhibits an interesting spatial orientation involving a release of toxic hydrogen peroxide into the extracellular space. The inactive amine oxidase protein located inside the cell is most probably the amine oxidase AO-II, found in cell homogenates. It is also likely that the less active AO-II is an improperly folded precursor of AO-I, which acquired low-level activity after cell homogenization in the presence of Cu(II) and oxygen due to autooxidative formation of topaquinone.

Amine Oxidase (Copper-Containing)↗
PubMed2006

Ferritin-catalyzed consumption of hydrogen peroxide by amine buffers causes the variable Fe2+ to O2 stoichiometry of iron deposition in horse spleen ferritin.

Ferritin catalyzes the oxidation of Fe2+ by O2 to form a reconstituted Fe3+ oxy-hydroxide mineral core, but extensive studies have shown that the Fe2+ to O2 stoichiometry changes with experimental conditions. At Fe2+ to horse spleen ferritin (HoSF) ratios greater than 200, an upper limit of Fe2+ to O2 of 4 is typically measured, indicating O2 is reduced to 2H2O. In contrast, a lower limit of Fe2+ to O2 of approximately 2 is measured at low Fe2+ to HoSF ratios, implicating H2O2 as a product of Fe2+ deposition. Stoichiometric amounts of H2O2 have not been measured, and H2O2 is proposed to react with an unknown system component. Evidence is presented that identifies this component as amine buffers, including 3-N-morpholinopropanesulfonic acid (MOPS), which is widely used in ferritin studies. In the presence of non-amine buffers, the Fe2+ to O2 stoichiometry was approximately 4.0, but at high concentrations of amine buffers (0.10 M) the Fe2+ to O2 stoichiometry is approximately 2.5 for iron loadings of eight to 30 Fe2+ per HoSF. Decreasing the concentration of amine buffer to zero resulted in an Fe2+ to O2 stoichiometry of approximately 4. Direct evidence for amine buffer modification during Fe2+ deposition was obtained by comparing authentic and modified buffers using mass spectrometry, NMR, and thin layer chromatography. Tris(hydroxymethyl)aminomethane, MOPS, and N-methylmorpholine (a MOPS analog) were all rapidly chemically modified during Fe2+ deposition to form N-oxides. Under identical conditions no modification was detected when amine buffer, H2O2, and O2 were combined with Fe2+ or ferritin separately. Thus, a short-lived ferritin intermediate is required for buffer modification by H2O2. Variation of the Fe2+ to O2 stoichiometry versus the Fe2+ to HoSF ratio and the amine buffer concentration are consistent with buffer modification.

Amines↗
PubMed1989

Peroxidase as a model for reduction of tertiary amine oxides catalyzed by rat hepatic supernatant and microsomal fractions.

Rat hepatic microsomal and 100,000 g supernatant fractions catalyzed an NADH- and FMN-dependent reduction of amine oxides. Horseradish peroxidase (HRP) served as a model for the amine oxide reductase located in rat hepatic 100,000 g supernatant fraction. The HRP-catalyzed reaction displayed saturation kinetics with respect to NADH and the amine oxide substrate; however, there was an optimum concentration for FMN after which inhibition was observed at increased concentrations of FMN. The reductase in the 100,000 g hepatic supernatant fraction closely paralleled HRP-catalyzed amine oxide reduction in coenzyme requirements, sensitivity to inhibitors, and substrate specificity. Moreover, the peroxidase activity of HRP and microsomal and 100,000 g supernatant fractions correlated with the NADH- and FMN-dependent amine oxide reductase activities of these enzyme preparations. The NADH- and FMN-dependent amine oxide reductase activity in 100,000 g supernatant fractions, however, did not parallel the aldehyde oxidase activity. Thus, the results indicate that there is an amine oxide reductase in rat hepatic 100,000 g supernatant fraction with catalytic properties that are modeled well by horseradish peroxidase.

Amines↗
PubMed1979

Modulatory role for biogenic amines in the cerebral cortex. Microiontophoretic studies.

In order to investigate the mode of action of biogenic amines in rat cerebral cortex, the unitary activity of spontaneously firing neurons and their excitatory response to acetylcholine (ACh) were examined using microiontophoretic administration of dopamine (DA), noradrenaline (NA) and serotonin (5-HT). The predominant effect of these biogenic amines on the spontaneous activity was a profound and prolonged inhibition of firing (2-4 min), which attained its maximum within 15-120 sec. This response was generally more abrupt in onset and of greater magnitude with NA and 5-HT than with DA. Most units inhibited by DA, NA and 5-HT also showed marked depression of their excitatory response to ACh when pretreated with these biogenic amines. With repetitive administration of ACh, it could be shown that the total duration of inhibition of ACh responses by DA and NA was not as prolonged as the inhibition of the spontaneous firing of the same cells. With 5-HT, the initial ACh responses of many neurons could be completely blocked, and this inhibitory effect lasted as long as the inhibition of spontaneous firing. In view of the anatomical data demonstrating a relative sparsity of monoamine nerve terminals in cerebral cortex, the strong inhibition induced by DA, NA or 5-HT may have reflected slow inactivation of the biogenic amines. However, it could also be indicative of underlying mechanisms of action dependent on metabolic changes. Indeed, the interaction between biogenic amines and ACh might imply a balance between the intracellular pools of cAMP and cGMP is directly or indirectly influenced by the biogenic amines and ACh, respectively. This hypothesis would not exclude other modes of local interaction between DA, NA, 5-HT and ACh, and appears compatible with the modulatory role of biogenic amines in cerebral cortex.

Acetylcholine↗
PubMed1992

Chromatographic methods for the analysis of heterocyclic amine food mutagens/carcinogens.

A series of potent heterocyclic amines that are mutagenic and carcinogenic have been discovered that are formed in some heated foods, most notably, meats derived from muscle. Determining the heterocyclic amine content in foods and food products is required for toxicological research, industry quality control, and possibly in the future, regulatory control. The contents of food needs to be determined using reliable analytical techniques. Since heterocyclic amines are present in foods at ng/g levels, a variety of liquid-liquid or solid-phase purification techniques are required, followed by gas or high-performance liquid chromatography. Peak detection has been successful using UV, fluorescence, and mass spectrometric detection, and biological activity using the Ames/Salmonella test. The low levels present require that chromatographic efficiency, and both detector sensitivity and selectivity be optimized. The cartridge solid-phase extraction and high-performance liquid chromatography method have been used to measure the known food-derived heterocyclic amines for several types of food, and to the authors knowledge, this is the only method undergoing intralaboratory comparison and validation. Our analysis of the literature shows that chromatographic analysis of the heterocyclic amines by high-performance liquid chromatography or gas chromatography (with derivatization) is satisfactory for heterocyclic amine analysis in foods although the methods are just now being optimized for routine use. The biggest improvements in speed and accuracy will probably come from improved extraction methods as analysis of complex food samples for heterocyclic amines will always be a challenge.

Amines↗
PubMed1994

Purification and active-site characterization of equine plasma amine oxidase.

An improved purification scheme for an amine oxidase from equine plasma (EPAO), a nonruminant source, is described and the protein's active-site is characterized. EPAO is dimeric and contains one Type-2 Cu(II) ion per monomer. The EPAO Cu(II) site is spectroscopically very similar to the Cu(II) sites in other amine oxidases. Unlike the extensively investigated nonruminant amine oxidase from porcine plasma, EPAO does not display half-of-the-sites reactivity; titrations with p-nitrophenylhydrazine and phenylhydrazine indicate two active cofactors per dimer. This cofactor is determined to be the same as that of other copper-containing amine oxidases, 6-hydroxydopa quinone (topa quinone). Upon anaerobic reduction with substrate at ambient temperature, the EPR spectrum of EPAO exhibits a sharp signal at g congruent to 2, attributable to the topa semiquinone. Equine plasma amine oxidase possesses novel in vitro substrate specificity; while other mammalian amine oxidases oxidize norepinephrine only slowly or not at all, EPAO displays significant activity toward this biogenic amine.

Amine Oxidase (Copper-Containing)↗
PubMed1991

Application of high-performance liquid chromatography to the study of biogenic amine-related enzymes.

The application of high-performance liquid chromatography to the study of biogenic amine-related enzymes is reviewed. Biogenic amines include catecholamines (dopamine, norepinephrine and epinephrine), indoleamines (serotonin and melatonin), imidazoleamines (histamine), polyamines (putrescine, spermidine and spermine) and acetylcholine. Three particular aspects are covered. The first aspect is the assay of enzyme activities of biogenic amine-related enzymes, such as tyrosine hydroxylase, tryptophan hydroxylase, aromatic L-amino acid decarboxylase, dopamine beta-hydroxylase and phenylethanolamine N-methyltransferase. The introduction of highly sensitive assays of biogenic amines with electrochemical detection or fluorescence detection have made possible the non-isotopic assay of these activities, replacing the previously used radioisotopic methods. The second aspect is the purification of these enzymes. Since biogenic amine-synthesizing enzymes are generally unstable, rapid and efficient purification of these enzymes is very useful. The third aspect is the assay of biogenic amines (for example, acetylcholine and polyamines) using post-column derivatization with biogenic amine oxidases and electrochemical detection.

Animals↗
PubMed2004

Chemical and enzymatic interactions of Direct Black 38 and Direct Brown 1 on release of carcinogenic amines.

Release of amine products from azo compounds is of considerable interest, since most of the metabolized amine products have toxic and carcinogenic characters. Moreover, most of the azo dyes are extensively used as coloring agents in inks, textiles, leathers, food and pharmaceutical industries. The present study emphasis on the quantification and comparison of amines released from water soluble dyes by (i) extra cellular protein (ECP) of Streptomyces sp. SS07 and by (ii) chemical methods. It has been observed that both the methods release considerable quantities of similar type of amine products. Release of amine compounds by ECP and chemical reduction in acid and alkaline sweat medium from a leather garment sample was also assessed. ECP (0.7852 mg protein/mg of ECP) releases benzidine and 4-amino biphenyl from Direct Black 38 and Direct Brown 1 as stable products at pH 9.2 and at 37 degrees C for a contact period of 24 h. On comparison with chemical reduction, it was observed that about 5-20% increase in the release of amine products by ECP was observed. However, more than 60% of amine products were released by chemical method from leather garment samples than direct treatment with ECP.

Amines↗
PubMed2004

New solvent systems for thin-layer chromatographic determination of nine biogenic amines in fish and squid.

Different solvent systems were evaluated for their ability to separate biogenic amines by thin-layer chromatography (TLC). Dansyl derivatives of agmatine, putrescine, tryptamine, cadaverine, spermidine, histamine, spermine, tyramine and beta-phenylethylamine were separated using the solvent system chloroform-diethyl ether-triethylamine (6:4:1), followed by chloroform-triethylamine (6:1). After separation dansyl amines were quantified by fluorescence densitometry at 330 nm. Correlation coefficients of linear regressions were higher than 0.99 for all amines, except for agmatine (0.976). Detection limits were 10ng for tryptamine, tyramine, histamine and beta-phenylethylamine, and 5 ng for the other amines. The overall repeatability of the chromatography was 1.82% when including agmatine and barely 1.02% for the other amines. The accuracy ranged from 105.97% (agmatine) to 49.92% (tryptamine). This thin-layer chromatography method was found to be an effective and precise analytical procedure to separate and determine biogenic amines. Its main advantages compared to previous procedures are that it uses less harmful solvent (diethyl ether instead of benzene) and can separate a larger group of biogenic amines.

Animals↗