Presence Of Methylamine Research Articles

Thermal decomposition behavior of potassium and sodium jarosite synthesized in the presence of methylamine and alanine

Biomolecules, methylamine and alanine, found associated with natural jarosite samples peaked the interest of astrobiologists and planetary geologists. How the biomolecules are associated with jarosite remains unclear although the mechanism could be important for detecting biosignatures in the rock record on Earth and other planets. A series of thermal gravimetric experiments using synthetic K-jarosite and Na-jarosite were conducted to determine if thermal analysis could differentiate physical mixtures of alanine and methylamine with jarosite from samples where the methylamine or alanine was incorporated into the synthesis procedure. Physical mixtures and synthetic experiments with methylamine and alanine could be differentiated from one another and from the standards by thermal analysis for both the K-jarosite and Na-jarosite end-member suites. Changes included shifts in on-set temperatures, total temperature changes from on-set to final, and the presence of indicator peaks for methylamine and alanine in the physical mixture experiments.

Interaction of methylamine with extrinsic and intrinsic subunits of photosystem II

The interaction of methylamine with chloroplasts' photosystem II (PSII) was studied in isolated thylakoid membranes. Low concentration of methylamine (mM range) was shown to affect water oxidation and the advancement of the S-states. Modified kinetics of chlorophyll fluorescence rise and thermoluminescence in the presence of methylamine indicated that the electron transfer was affected at both sides of PSII, and in particular the electron transfer between Y Z and P680 +. As the concentration of methylamine was raised above 10 mM, the extrinsic polypeptides associated with the oxygen-evolving complex were lost and energy transfer between PSII antenna complexes and reaction centers was impaired. It was concluded that methylamine is able to affect both extrinsic and intrinsic subunits of PSII even at the lowest concentrations used where the extrinsic polypeptides of the OEC are still associated with the luminal side of the photosystem. As methylamine concentration increases, the extrinsic polypeptides are lost and the interaction with intrinsic domains is amplified resulting in an increased F 0.

Synthesis and conformational study of some r(2), c(4)-bis(isopropoxycarbonyl)- t(3)-aryl- c(5)-hydroxy- t(5)-methylcyclohexanones using NMR spectra

Seven r(2), c(4)-bis(isopropoxycarbonyl)- t(3)-aryl- c(5)-hydroxy- t(5)-methylcyclohexanones 7– 13 (aryl = C 6H 5, p-ClC 6H 4, p-FC 6H 4, p-OMeC 6H 4, p-Me 2NC 6H 4, m-O 2NC 6H 4 and m-C 6H 5OC 6H 4) have been synthesized by condensing isopropyl acetoacetate with aromatic aldehydes in the presence of methylamine. For all these compounds 1H and 13C NMR spectra have been recorded. For 7, HOMOCOSY, NOESY, HSQC and HMBC spectra also have been recorded. The spectral data suggest that compounds 7– 13 exist in chair conformation with axial orientation of the hydroxy group and equatorial orientations of all the other substituents. Long range coupling is observed between OH proton and H(6a) in all cases suggesting that OH group is anti to C(5) C(6) bond. In all cases four distinct doublets are observed for the methyl protons of the two isopropyl groups. In 7 and 13 four separate, closely spaced signals are observed for the methyl carbons of the two isopropyl groups. All signals could be assigned unambiguously in the case of 7. The protons of one methyl group of the isopropoxycarbonyl group at C-4 seems to be highly shielded. This suggests that these protons lie above the plane of the aryl group at C(3). This conclusion is in accordance with the structure of 7, determined by X-ray crystallography. MOPAC calculations on 7 suggest that the chair conformation with OH group anti to C(5) C(6) bond is more stable than the chair conformation with OH bond anti to C(5) CH 3 bond by 1.5 kcal mol −1.

Practical Enantioselective Synthesis of β-Substituted-β-amino Esters

[reaction: see text] A practical, large-scale synthesis of a beta-amino ester 1 was developed. A chiral imine derived from (S)-phenylglycinol and 3-trimethylsilylpropanal was coupled with the Reformatsky reagent 3 with high diastereoselectivity (de > 98%) to give (SS)-4a as the major isomer. The amino alcohol residue of the coupling product 4 was oxidatively cleaved with sodium periodate in the presence of methylamine. An unusual selective oxidative cleavage of the (SS)-isomer was observed and the imine 6 was obtained with ee > 99% while the (RS)-4b isomer was not cleaved. Reaction with p-toluenesulfonic acid monohydrate allowed for the hydrolysis of the imine and the isolation of the amine as its salt. The title compound 1 was then obtained by transesterification, desilylation, and hydrochloride salt formation in a one-pot process. The method was successfully applied toward the synthesis of a wide variety of beta-amino esters.

Fluorinated Heterocyclic Compounds. A Photochemical Approach to a Synthesis of Polyfluoroaryl‐1,2,4‐triazoles.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Long-Term Plasticity Mediated by mGluR1 at a Retinal Reciprocal Synapse

The flow of information across the retina is controlled by reciprocal synapses between bipolar cell terminals and amacrine cells. However, the synaptic delays and properties of plasticity at these synapses are not known. Here we report that glutamate release from goldfish Mb-type bipolar cell terminals can trigger fast (delay of 2-3 ms) and transient GABA(A) IPSCs and a much slower and more sustained GABA(C) feedback. Synaptically released glutamate activated mGluR1 receptors on amacrine cells and, depending on the strength of presynaptic activity, potentiated subsequent feedback. This poststimulus enhancement of GABAergic feedback lasted for up to 10 min. This form of mGluR1-mediated long-term synaptic plasticity may provide retinal reciprocal synapses with adaptive capabilities.

Transferrin Uptake by Cultured Rat Embryo Fibroblasts

The effect of different drugs which affect lysosomal function (chloroquine, methylamine) and endocytosis (colchicine) or of the iron chelators desferrioxamine B, rhodotorulic acid, bipyridyl, 2,3-dihydroxybenzoic acid, isoniazid pyridoxal hydrazone on the uptake of 59Fe-loaded 3H-labelled transferrin by cultured rat embryo fibroblasts has been studied. All these substances, except isoniazid pyridoxal hydrazone reduce the uptake of iron by fibroblasts, without any significant effect on the uptake of [3H]transferrin, nor of its specific binding to the cells. Cell fractionation experiments indicate that in the presence of methylamine and chloroquine, most of the cell associated 3H label is no longer transferred into lysosomes and remains associated with subcellular compartments which have a 5'-nucleotidase activity (a marker enzyme of plasma membrane and related structures such as endocytic vesicles). Short-term kinetic experiments with fibroblasts incubated for 1 min at 37 °C with doubly labelled transferrin show that on reincubation in fresh medium almost all of the 59Fe initially bound remains associated with the cells whereas the 3H-labelled transferrin is released with a t1/2 of about 1.5 min. In the presence of desferrioxamine B both 59Fe and transferrin, the former in part as ferrioxamine, are released from the cells with the same kinetics as is observed for transferrin in the control experiments. Similar studies with cells preincubated for 16 h with chloroquine or methylamine indicate that the release of transferrin from the cells is slowed down considerably. Chloroquine-treated cells also release large amounts of 59Fe. These results are consistent with the model for iron release from transferrin proposed previously [1] involving receptor mediated endocytosis of transferrin followed by release of iron during a rapid passage of the transferrinreceptor complex in lysosomes and recycling of the complex to the plasma membrane where the iron-depleted transferrin is released. The inhibition of iron uptake by iron chelators such as desferrioxamine is consistent with complexation of iron by the chelator subsequent to its release from transferrin inside the cells and transfer of the iron-chelate into the extracellular medium.

Synthesis and NMR spectral study of somet(3)-aryl-r(2),c(4)-bisethoxycarbonyl-t(5)-hydroxy-c(5)-methylcyclohexanones

Six t(3)-aryl-r(2),c(4)-bisethoxycarbonyl-t(5)-hydroxy-c(5)-methylcyclohexanones (6-11) were synthesized by condensing ArCHO (Ar = Ph, p-O(2)NC(6)H(4), p-CH(3)OC(6)H(4), p-ClC(6)H(4), m-O(2)NC(6)H(4) and m-C(6)H(5)O(6)H(4)) with ethyl acetoacetate in the presence of methylamine and their (1)H and (13)C NMR spectra were recorded. (1)H-(1)H COSY and NOESY spectra were recorded for 6 and 7 and also HSQC and HMBC spectra for 6 and 8. Elemental analysis was carried out for all compounds. The mass spectrum was recorded for 8. All analytical data are consistent with the proposed molecular formulae. Analysis of NMR spectral data suggests that these compounds largely adopt chair conformations with the hydroxyl group occupying an axial orientation and all the other substituents occupying equatorial orientations. Long-range coupling (2-3 Hz) between the OH proton and the axial methylene proton at C-6 is observed in 6, 7, 8 and 11.

Fluorinated Heterocyclic Compounds. A Photochemical Approach to a Synthesis of Polyfluoroaryl-1,2,4-triazoles

The reaction of some fluorinated 1,2,4-oxadiazoles in the presence of methylamine or propylamine has been investigated. The irradiation in methanol or acetonitrile leads with acceptable yields to the corresponding fluorinated 1- methyl- or 1-propyl-1,2,4-triazole.

FTIR Study of Adsorption and Reactions of Methylamine on Powdered TiO2

The adsorption, thermal reactions, and photochemistry of methylamine on TiO2 have been investigated using infrared spectroscopy. It is found that methylamine is adsorbed molecularly on TiO2 at 35 °C. Hydrogen exchange occurs between the NH2 group of adsorbed methylamine and surface OH groups. Thermal reactivity of methylamine is enhanced in the presence of O2, producing NH3(g), CO2(g), and other oxygenated compounds. UV irradiation of TiO2 in the presence of methylamine and oxygen generates NH3(g), CO2(g), H2O(g), NCO(a), and HCOO(a). Possible reaction steps for the photoproducts are discussed.

Ammonium and methylammonium uptake in a fertilizer-degrading strain of Ochrobactrum anthropi.

The transport of ammonium and methylammonium was studied in a strain of Ochrobactrum anthropi, a microorganism isolated from garden soil and able to degrade methyleneureas which are used as slow-release nitrogen fertilizer. The activity of both transport systems was determined using [14C]methylammonium. Differences between the two transport systems were observed with regard to their pH- and temperature dependence as well as their kinetic parameters and regulation during growth with various nitrogen sources. Ammonium transport was subject to repression by ammonium and to derepression in its absence, while the methylammonium carrier was induced in the presence of methylamine. The ammonium but not the methylammonium transport system was severely inhibited by ammonium, and metabolic poisons inhibited both uptake systems. The analysis of intracellular metabolites using thin-layer chromatography and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry indicated that methylammonium was rapidly metabolized to N-methylglutamate via gamma-N-methylglutamine.

Heterologous expression of correctly assembled methylamine dehydrogenase in Rhodobacter sphaeroides.

The biosynthesis of methylamine dehydrogenase (MADH) from Paracoccus denitrificans requires four genes in addition to those that encode the two structural protein subunits, mauB and mauA. The accessory gene products appear to be required for proper export of the protein to the periplasm, synthesis of the tryptophan tryptophylquinone (TTQ) prosthetic group, and formation of several structural disulfide bonds. To accomplish the heterologous expression of correctly assembled MADH, eight genes from the methylamine utilization gene cluster of P. denitrificans, mauFBEDACJG, were placed under the regulatory control of the coxII promoter of Rhodobacter sphaeroides and introduced into R. sphaeroides by using a broad-host-range vector. The heterologous expression of MADH was constitutive with respect to carbon source, whereas the native mau promoter allows induction only when cells are grown in the presence of methylamine as a sole carbon source and is repressed by other carbon sources. The recombinant MADH was localized exclusively in the periplasm, and its physical, spectroscopic, kinetic and redox properties were indistinguishable from those of the enzyme isolated from P. denitrificans. These results indicate that mauM and mauN are not required for MADH or TTQ biosynthesis and that mauFBEDACJG are sufficient for TTQ biosynthesis, since R. sphaeroides cannot synthesize TTQ. A similar construct introduced into Escherichia coli did not produce detectable MADH activity or accumulation of the mauB and mauA gene products but did lead to synthesizes of amicyanin, the mauC gene product. This finding suggests that active recombinant MADH is not expressed in E. coli because one of the accessory gene products is not functionally expressed. This study illustrates the potential utility of R. sphaeroides and the coxII promoter for heterologous expression of complex enzymes such as MADH which cannot be expressed in E. coli. These results also provide the foundation for future studies on the molecular mechanisms of MADH and TTQ biosynthesis, as well as a system for performing site-directed mutagenesis of the MADH gene and other mau genes.

Affinity chromatography purification of mitochondrial inner membrane proteins with calcium transport activity

Immobilized calcium affinity chromatography was used to obtain a preparation enriched in calcium transporters from Triton X-100 extracts of rat liver mitochondria inner membranes (PPCT). The PPCT were reconstituted into performed asolectin liposomes which contained 120 mM KCl as internal high K + medium. 45Ca 2+ uptake into proteoliposomes was studied under conditions favoring electrophoretic uptake, and H i +/ 45Ca 0 2+ or Na i +/ 45Ca 0 2+ exchange, to test for the presence of the three calcium transport modes present in mitochondria. 45Ca 2+ uptake in liposomes was studied in parallel. Na i +/ 45Ca o 2+ exchange activity was not detectable. H i +/ 45Ca o 2+ exchange activity measured in the presence of a pH gradient (acid inside) obtained after suspension in low K medium in the presence of nigericin, was 100–200 nmoles 45Ca 2+ per mg protein in 30 s. 45Ca 2+ uptake in voltage-dependent assays (a K + diffusion membrane potential induced by valinomycin in the presence of methylamine) was not electrophoretic since it was stimulated by carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) and probably due to secondary Ca 2+/H + countertransport. H i +/ 45Ca o 2+ uptake showed a saturable component at around 80 μM Ca and was coupled to increase in internal pH in pyranine-loaded PPCT proteoliposomes. 45Ca 2+ uptake in PPCT proteoliposomes could also be driven by a pH gradient obtained by raising external pH in high K + medium. The results are consistent with the presence of a functional nH +/Ca 2+ antiporter. Polyclonal antibodies raised against the PPCT were able to immunoprecipitate the H +/ 45Ca 2+ uptake activity and recognized two major bands in the PPCT with molecular masses of about 66 kDa and 55 kDa. This is the first report of a partial purified protein(s) which may represent the H +/Ca 2+ exchanger of the inner mitochondrial membrane, and represents an important step towards its identification.

Cleaner production of phenylacetylcarbinol by yeast through productivity improvements and waste minimiaation

Abstract

Labelling the Ca2+-ATPase of skeletal-muscle sarcoplasmic reticulum with the cross-linker o-phthalaldehyde

The Ca(2+)-ATPase in the sarcoplasmic reticulum of skeletal muscle reacts with o-phthalaldehyde (OPA) to form a fluorescent isoindole product. The stoichiometry of labelling of the ATPase is 9 nmol of isoindole/mg of ATPase, corresponding to a 1:1 molar ratio of isoindole: ATPase. There is no evidence for any intermolecular cross-linking. Isoindole formation is faster in the presence of methylamine, but the stoichiometry of labelling is unchanged, whereas in the presence of 2-mercaptoethanol the level of labelling is much higher. It is concluded that OPA reacts with a single Cys residue (defining the specificity of the reaction) in a fast step, subsequent reaction with a Lys residue to form the isoindole being rate-controlling. Labelling the ATPase with OPA in the absence of methylamine leads to total loss of ATPase activity, whereas in the presence of methylamine, the decrease in ATPase activity on reaction is small. We conclude that the loss of ATPase activity probably follows from formation of the intramolecular cross-link rather than from the initial modification of the Cys residue. Reaction with OPA is not affected by the presence of ATP, ADP or Ca2+, so that the reactive Cys is not part of a ligand-binding site. The fluorescence emission spectrum of the labelled ATPase indicates a hydrophobic environment for the isoindole ring.

Manipulating cytoplasmic pH under anoxia: A critical test of the role of pH in the switch from aerobic to anaerobic metabolism

Ethanol production by maize (Zea mays L.) root tips, measured by an enzymic assay of the suspending medium, was correlated with changes in the cytoplasmic pH, determined by in-vivo 31P nuclear magnetic resonance (NMR) spectroscopy, following the onset of anoxia. Strong evidence for the role of the cytoplasmic pH in triggering the switch to ethanol production under anoxia was obtained by: (i) varying the pH of the suspending medium between pH 4 and pH 10; and (ii) using the permeant weak base methylamine to combat the acidification of the cytoplasm induced by the anoxic conditions. Experimentally, it proved to be much easier to manipulate the cytoplasmic pH under anoxia after the pH had stabilised, rather than during the initial rapid acidification that occurred following the onset of anoxia, and in the presence of methylamine, it was possible to impose a normal aerobic cytoplasmic pH value on tissue that was metabolising anaerobically. By this means it was possible to demonstrate the reversibility of the pH effect on ethanol production under anoxia and thus to provide good evidence in support of the biochemical pH-stat model of the anoxic response. The NMR measurement of the cytoplasmic pH in the presence of methylamine was achieved by using a manganese pretreatment technique to eliminate interference between the cytoplasmic and vacuolar Pi signals, and it seems likely that the experimental approach used here will have further applications in studies of the metabolic response to anoxia.

N-Methyl-β-carboline-3-carboxamide (FG 7142): An anxiogenic agent in cigarette smoke condensate and its mechanism of formation

β-Carboline-3-carboxylic acid methylamide (FG 7142), an anxiogenic agent has been found in cigarette smoke condensate, but not in the cigarette itself. When a cigarette, except its filter portion, was immersed in 20 ml of potassium phosphate buffer, pH 7·4, then heated at 60°C for 2 days with or without presence of methylamine, FG 7142 was detected only in the mixture containing methylamine. Furthermore, when the mixtures of β-carboline derivatives and various amounts of methylamine hydrochloride were heated at 60°C for 5 days, FG 7142 was formed only in the mixtures containing methylamine and 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-caroxylic acid (MTCA) or 1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (TCCA). FG 7142 was also produced in the mixture of glucose, l-tryptophan and methylamine when heated at 200°C in a dry condition. These observations suggest that FG 7142 is formed through the smoking process and that methylamine in cigarette smoke may play an important role in the formation of FG 7142.

The Effect of pH on the Covalent and Metabolic Control of C 4 Phospho enolpyruvate Carboxylase from Sorghum Leaf

The influence of pH on the in vitro activity and regulatory properties of Sorghum leaf C 4 phospho enolpyruvate carboxylase (PEPC) was investigated with respect to the phosphorylation status of the enzyme. In vitro protein phosphorylation was achieved using the catalytic subunit of a cAMP-dependent protein kinase (PKA) and a recombinant, immunopurified PEPC (0.9 mol of covalent P i/mol PEPC subunit). Between pH 6.8 and 8, velocity and IC 50 for L-malate increased for both the nonphosphorylated and the phosphorylated forms. With respect to the nonphosphorylated PEPC, the phospho-PEPC always gave high values for these kinetic parameters at the pH range investigated, especially between pH 7 and 7.3. The phosphorylation-induced stimulation of PEPC activity was four- to fivefold at pH 7.1 and approximately twofold at pH 7.3. The IC 50 for L-malate showed a two- to threefold increase at pH 7.3, but varied less at pH 7.1 upon PEPC phosphorylation. Thus, phosphorylation of PEPC caused a predominant V effect or a mixed (V/IC 50) effect at pH 7.1 or 7.3, respectively. This was also observed with the enzyme from desalted crude protein extracts from dark or light-adapted Sorghum leaves and leaf-derived mesophyll protoplasts illuminated in the presence of methylamine, a compound known to increase cytosolic pH (pHc). At pH 7.3, desensitization to L-malate pf phospho-PEPC was due to an enhanced ability of PEP to compete with the inhibitor. The positive effector glucose-6P acted similarly to phosphorylation; however a combination of both factors (glucose-6P and phosphorylation) led to a much larger increase in the IC 50 for L-malate than that observed by a single factor. These effects may account for the actual CO 2 assimilation rate of an illuminated Sorghum leaf. In reconstituted assays performed at pH 7.1 or 7.3, in the presence of PKA, the addition of 10 mM L-malate decreased the phosphorylation rate of the PEPC. This effect was strongly inhibited by the addition of glucose-6P (5 mM). It is suggested that modulation of the phosphorylation rate is partly through conformational changes in the PEPC induced by these photosynthetic metabolites. Together with previous findings indicating that the photoinduction of PEPC protein kinase was strictly dependent on cytosolic alkalization in meosphyll cell protoplasts (J. N. Pierre et al., 1992, Eur. J. Biochem. 210, 531-537), the present data support the view that cytosolic pH is an important component of the overall regulation of PEPC in C 4-photosynthesis. Finally, the role of phosphorylation appears to be a mechanism to amplify the regulatory influences of pHc and glucose-6P on PEPC activity.

On the Stability of Clathrate Hydrates Encaging Polar Guest Molecules: Contrast in the Hydrogen Bonds of Methylamine and Methanol Hydrates

Abstract The stability of clathrate hydrates encaging highly polar guests has been investigated in order to explain the experimental observation that some amines form clathrate hydrates but alcohols act as inhibitor to hydrate formation. We choose methylamine and methanol as guest species and examine the stable structure, at which the total potential energy has a minimum value. At the local minima of those two hydrates, the potential energies of water-water and guest-water, and their hydrogen bonded networks are compared. It is found that methanol does not retain the host lattice structure, while the host-network structure is kept in the presence of methylamine. It is shown that the difference in the magnitude of the partial charge on the hydrogen atom between the hydroxyl and amino groups plays a much more significant role on the stability of both clathrate hydrates than the difference in molecular geometry. This is supported from the result of a methylamine-like model that has the same partial charges on the atoms in the hydrophilic site as methanol.

C1 Inhibitor and Diagnosis of Hereditary Angioedema in Newborns

Symptoms of hereditary angioedema may present during the child's first years. Attacks may be a particular threat to the narrower airway of the child. An early diagnosis is most valuable because effective C1 inhibitor (C1 INH) concentrate is available. We present a reference area for the antigenic and functional determination of C1 INH by using uncontaminated umbilical cord blood from 80 normal newborns collected by puncturing vessels in the newly delivered placenta. We examined two full-term babies (1 and 2) from mothers with hereditary angioedema type I the same way. The concentration of C1 INH antigen was determined by radial immunodiffusion. The C1 INH functional assay was based on the addition of a known quantity of C1s, which enzymatically splits a chromogenic substrate. The test was performed in the presence of methylamine and heparin in a kinetic microtiter plate assay. Citrated plasma was used in both assays. The data obtained in the 80 cord blood samples (2.5-97.5 percentile) were 0.11-0.22 g/L for C1 INH antigen (adults, 0.15-0.33 g/L) and 47.2-85.9% for C1 INH function (percentage of adults). In cord blood, baby 1 had an antigenic value of 0.12 g/L (7.5 percentile) and C1 INH function of 61.8% (42 percentile). The corresponding values for baby 2 in cord blood were less than 0.05 g/L (0.106 g/L < 2.5 percentile) and 34.3% (12.9% < 2.5 percentile). Baby 2 had markedly lower C4 values yet much higher C4 activation products than baby 1. At 4 mo, baby 1 had an antigenic C1 INH value of 0.24 g/L.(ABSTRACT TRUNCATED AT 250 WORDS)