Determination of Carbon and Nitrogen Isotope Fractions in Asparagine, Aspartic Acid, Threonine and Methionine

The nomenclature for compounds that are modified with isotopes is growing every day. Compounds can be modified with isotopes either individually, in a functional group or groups, or completely with all atomic centers of the element. This diversity of isotope-modified compounds increases the range of researches that can be studied using them. Compounds modified with isotopes of carbon-13 or nitrogen-15 can be converted into carbon monoxide, carbon dioxide and molecular nitrogen. Currently, only the average value of carbon-13 or nitrogen-15 isotopes can be determined. However, by directly determining the atomic share of these isotopes in organic compounds modified with isotopes, information about the isotopic centers of the element can be obtained. The atomic fraction of an element is defined as a single carbon or nitrogen isotope-modified center or centers, or all centers that are isotope-modified with that element at the same time. Carbon-13 or nitrogen-15 isotopes’ atomic fraction can be determined molecularly or with fragment ions of different elemental content, or both. This makes the method self-verifying, increasing the accuracy and reliability of the results obtained. Amino acids, such as asparagine, aspartic acid, methionine, and threonine, are essential for the human body. This proposed method of isotopic analysis will increase the possibilities for scientific research using these compounds.

Effects of the Amino Acids of Aspartate Family on the Biosynthesis of CoQ_(10) in Rhodopseudomonas palustris J001

[Objective]The study aimed to investigate the effects of the amino acids of aspartate family on the biosynthesis of CoQ10 in Rhodpseudomonas palustris J001.[Method]The impacts of amino acids of this family on the biosynthesis of CoQ10 in Rhodopseudomnas palustris J001 were investigated by feeding these amino acids at the end of the logarithmic phase during incubation,which aim was for the optimization of the fermentation medium and genetic improvement of the strain for CoQ10 production.[Result]The results showed that feeding proper amount of methione(125 mg/L)could increase CoQ10 production by 20.2%,but feeding of lysine(above 500 mg/L),threonine(above 400 mg/L)and/or isoleucine(above 400 mg/L)repressed the biosynthesis of CoQ10.The results indicated that the aspartate kinase is subject to feedback inhibition or repression by lysine,threonine and isoleucine in the strain,which was unfavorable to the formation of methioine and then caused the decrease of CoQ10 production.[Conclusion]Lysine,threonine and isoleucine auxotrophic mutants with resistance to analogues of lysine,threonine and isoleucine could increase the production of CoQ10.

Effect of single-use versus combined-use moschus and diazepam on expression of amino acid neurotransmitters in the rat corpus striatum

The present study analyzed expressional changes of excitatory neurotransmitters and inhibitory neurotransmitters in the rat corpus striatum after single-use and combined-use diazepam and Chinese herb moschus. The influence of moschus on the central nervous system was analyzed, in particular whether moschus increased penetration of other drugs into the brain. Reverse-phase high-performance liquid chromatography, which included pre-column derivation with orthophthaladehyde detection, showed varied increased levels of excitatory neurotransmitters, including aspartate and glutamate, and inhibitory neurotransmitters, including glycine and Y-aminobutyric acid, in the corpus striatum after treatment with moschus alone, diazepam alone, or a combination of both. Compared with the diazepam group, aspartate levels significantly decreased at 30 and 60-105 minutes after combined treatment with moschus, while glutamate significantly increased at 45 and 75-105 minutes, glycine levels significantly increased at 105 minutes, and γ-aminobutyric acid increased at 30 and 75-105 minutes. These findings suggested that moschus increased the inhibition effects of diazepam on the brain.

Ghrelin and gastric acid secretion

Ghrelin, a novel growth hormone-releasing peptide, was originally isolated from rat and human stomach. Ghrelin has been known to increase the secretion of growth hormone (GH), food intake, and body weight gain when administered peripherally or centrally. Ghrelin is also known to stimulate the gastric motility and the secretion of gastric acid. In the previous studies, the action of ghrelin on acid secretion was shown to be as strong as that of histamine and gastrin in in-vivo experiment. In the studies, the mechanism for the action of ghrelin was also investigated. It was shown that vagotomy completely inhibited the action of ghrelin on the secretion of gastric acid suggesting that vagal nerve is involved in the mechanism for the action of ghrelin on acid secretion. As famotidine did not inhibit ghrelin-in-duced acid secretion in the study by Masuda et al, they concluded that histamine was not involved in the action of ghrelin on acid secretion. However, we have shown that famotidine completely inhibited ghrelin-induced acid secretion and histidine decarboxylase (HDC) mRNA was increased in gastric mucosa by ghrelin injection which is inhibited by vagotomy Our results indicate that histamine is involved in the action of ghrelin on acid secretion. Furthermore synergistic action of gastrin and ghrelin on gastric acid secretion was shown. Although gastrin has important roles in postprandial secretion of gastric acid, ghrelin may be related to acid secretion during fasting period or at night. However, further studies are needed to elucidate the physiological role of ghrelin in acid secretion.

High Temperature During Rice Grain Filling Enhances Aspartate Metabolism in Grains and Results in Accumulation of AspartateFamily Amino Acids and Protein Components

Global warming causes the exacerbation of rice growing environment, which seriously affects rice growth and reproduction, and finally results in the decrease of rice yield and quality. We investigated the activities of aspartate metabolism enzymes in grains, and the contents of Aspartate-family amino acids and protein components to further understand the effects of high temperature （HT） on rice nutritional quality during rice grain filling. Under HT, the average activities of aspartate aminotransferase （AAT） and aspartokinase （AK） in grains significantly increased, the amino acid contents of aspartate （Asp）, lysine （Lys）, threonine （Thr）, methionine （Met） and isoleucine （lie） and the protein contents of albumin, globulin, prolamin and glutelin also significantly increased. The results indicated that HT enhanced Asp metabolism during rice grain filling and the enhancement of Asp metabolism might play an important role in the increase of Asp-family amino acids and protein components in grains. In case of the partial appraisal of the change of Asp-family amino acids and protein components under HT, we introduced eight indicators （amino acid or protein content, ratio of amino acid or protein, amino acid or protein content per grain and amino acid or protein content per panicle） to estimate the effects of HT. It is suggested that HT during rice grain filling was benefit for the accumulation of Asp-family amino acids and protein components. Combined with the improvement of Asp-family amino acid ratio in grains under HT, it is suggested that HT during grain filling may improve the rice nutritional quality. However, the yields of parts of Asp-family amino acids and protein components were decreased under HT during rice grain filling.

Microwave-assisted Synthesis of Modified Polyaspartic Acid in Solvent

Polyaspartic acid(PASP)is suitable for the inhibition of scale deposition from water.To enhance its in- hibition efficiency,PASP was modified by reacting aspartic acid(Asp)with glutamic acid(Glu)to provide Asp-Glu copolymer under microwave irradiation.The influence of reaction parameters on conversion,molecular weight and inhibition of CaCO3 precipitation was investigated Infra-red.(IR), 1H nuclear magnetic resonance( 1H NMR)and 13C nuclear magnetic resonance( 13C NMR)spectroscopies were used to characterize the copolymer.The results show that copolymerization of aspartic acid and glutamic acid is catalyzed by a small amount of phosphorous acid (H3PO4)in solvent,the product conversion is 98.05%under the following conditions:the molar ratio of glutamic acid to reactant[Glu/(Asp+Glu)]is 0.3 and that of catalyst(Cat)to reactant[Cat/(Glu+Asp)]is 0.05(0.65ml H3PO4),the volume of solvent dimethylformamide is 16ml,the microwave power used is 720W and the reaction for 3 min.The weight average molecular weight of copolymer synthesized under these conditions is 2709 and the inhi- bition rate for CaCO3 is 97.75%.

Bile acid increases expression of the histamine-producing enzyme,histidine decarboxylase,in gastric cells

AIM: To investigate the effect of bile acid on the expression of histidine decarboxylase (HDC), which is a major enzyme involved in histamine production, and gene expression of gastric transcription factors upon cooperative activation.

Progress of amino acid nutrition for diet protein reduction in poultry

There is growing interest among nutritionists in feeding reduced protein diets to broiler chickens.Although nearly a century of research has been conducted providing biochemical insights on the impact of reduced protein diets for broilers,practical limitation still exists.The present review was written to provide insights on further reducing dietary protein in broilers.To construct this review,eighty-nine peer reviewed manuscripts in the area of amino acid nutrition in poultry were critiqued.Hence,nutritional research areas of low protein diets,threonine,glycine,valine,isoleucine,leucine,phenylalanine,histidine,and glutamine have been assessed and combined in this text,thus providing concepts into reduced protein diets for broilers.In addition,linkages between the cited work and least cost formation ingredient and nutrient matrix considerations are provided.In conclusion,practical applications in feeding reduced protein diets to broilers are advancing,but more work is warranted.

Metal ion-binding properties of L-glutamic acid and L-aspartic acid, a comparative investigation

A comparative research has been developed for acidity and stability constants of M(Glu)1, M(Asp)2 and M(Ttr)3 complexes, which have been determined by potentiometric pH titration. Depending on metal ion-binding properties, vital differences in building complex were observed. The present study indicates that in M(Ttr) com-plexes, metal ions are arranged to the carboxyl groups, but in M(Glu) and M(Asp), some metal ions are able to build chelate over amine groups. The results mentioned-above demonstrate that for some M(Glu) and M(Asp) complexes, the stability constants are also largely determined by the affinity of metal ions for amine group. This leads to a kind of selectivity of metal ions, and transfers them through building complexes accompanied with glutamate and aspartate. For heavy metal ions, this building complex helps the absorption and filtration of the blood plasma, and consequently, the excursion of heavy metal ions takes place. This is an important method in micro-dialysis. In this study the different as-pects of stabilization of metal ion complexes regarding to Irving-Williams sequence have been investigated.

Poly(ethylenimine)-grafted-poly[(aspartic acid)-co-lysine]: A Non-viral Polymer with Potential for DNA Delivery

A biodegradable gene transfer vector, poly(ethylenimine)-grafted-poly[(aspartic acid)-co-lysine] has been developed by thermal polycondensation of aspartic acid and lysine, and branch poly(ethylenimine) (Mw less than 600) was grafted to the backbone. The polymer was characterized by 1H NMR. It appeared lower cytotoxity compared to poly(ethylenimine) (25KDa), which was quantified by MTT assay. Electrophoresis indicated that the polymer could retardate DNA at N/P ratio 1.2-1.8 (w/w). Transfection efficiency of the complexes was studied in NT2 cell lines. It was 1.5 fold higher than molecular weight PEI (Mw = 25KDa).

Detection of Serine Octamer by Desorption Electrospray Ionization Mass Spectrometry in Resultant Mixture of Aspartic Acid Exposed to Sunshine Under Natural Conditions

Serine, one of the nonessential amino acids, is of principal interest because of its capability to form magic-number ionic clusters, which provide a remarkable preference for homochirality. With L-aspartic acid as the precursor, this study provides experimental evidence for serine formation in weak acidified aqueous solutions in the presence of iron, with exposure to sunlight, which simulates the natural conditions of the prebiotic aqueous environment. The resultant mixture is directly analyzed via desorption electrospray ionization mass spectrometry（ DESI-MS）, without any sample preseparation. The serine monomer is successfully detected as protonated molecules, giving a peak at m/z 106, which is confirmed by the MS/MS fragments. Protonated serine octamer（ m/z 841 ） is also observed with significant abundance in the MS spectra and is confirmed by the MS/MS data, which shows the formation of the serine octamer by a synthesized serine in the resultant mixture. It is also found that the serine octamer yielded equivalent abundance in the DESI mass spectra in a wide pH range（pH = 1-5 ）, and that existence of ferrous salt and sunshine are essential for the conversion of aspartic acid to serine in the acidic water solution.

Synthesis,Characterization and Antibacterial Properties of Rare Earth (Ce^(3+) ,Pr^(3+) ,Nd^(3+) ,Sm^(3+) ,Er^(3+) ) Complexes with L-Aspartic Acid and o-Phenanthroline

Five novel ternary complexes of rare earth ions with L-Aspartic acid (Asp) and o-phenanthroline (Phen) were synthesized in ethanol aqueous solution. Their compositions were characterized by elemental analysis, molar conductance, FT-IR, Raman, UV-VIS and TG-DTA. The compositions of the complexes were confirmed to be: RE( Asp)3PhenCl3·3H2O (RE: Ce3+ , Pr3+ , Nd3+ , Sm3+ , Er3+ ). The antibacterial activity test shows that all these complexes exhibit excellent antibacterial ability against Escherichia coli, Staphylococcus aureus and Candida albicans. The antimicrobial spectrum of the complexes are broad.

Inhibition mechanism of aspartic acid on crystal growth of hydroxyapatite

The effects of aspartic acid on the crystal growth, morphology of hydroxyapatite(HAP) crystal were investigated, and the inhibition mechanism of aspartic acid on the crystal growth of hydroxyapatite was studied. The results show that the crystal growth rate of HAP decreases with the increase of the aspartic acid concentration, and the HAP crystal is thinner significantly compared with that without amino acid, which is mainly due to the (1 010) surface of HAP crystal being inhibited by the aspartic acids. The calculation analysis indicates that the crystal growth mechanism of HAP, following surface diffusion controlled mechanism, is not changed due to the presence of aspartic acid. AFM result shows that the front of terrace on vicinal growth hillocks is pinned, which suggests that the aspartic acid is adsorbed onto the (1 010) surface of HAP and interacts with the Ca2+ ions of HAP surface, so as to block the growth active sites and result in retarding of the growth of HAP crystal.

Effect of Chronic Noise Exposure on Expression of N-Methyl-D-Aspartic Acid Receptor 2B and Tau Phosphorylation in Hippocampus of Rats

Objective To study the effect of chronic noise exposure on expression of N-methyI-D-aspartic acid receptor 2B （NR2B） and tau phosphorylation in hippocampus of rats. Methods Twenty-four male SD rats were divided in control group and chronic noise exposure group. NR2B expression and tau phosphorylation in hippocampus of rats were detected after chronic noise exposure （100 dB SPL white noise, 4 h/dx30d） and their mechanisms underlying neuronal apoptosis in hippocampus of rats with TUNEL staining. Results The NR2B expression decreased significantly after chronic noise exposure which resulted in tau hyperphosphorylation and neural apoptosis in hippocampus of rats. Immunohistochemistry showed that the tau hyperphosphorylation was most prominent in dentate gyrus （DG） and CA1 region of rat hippocampus. Conclusion The abnormality of neurotransmitter system, especially Glu and NR2B containing NMDA receptor, and tau hyperphosphorylation in hippocampus of rats, may play a role in chronic noise-induced neural apoptosis and cognition impairment.

Effect of Xingnaojing Injection(醒脑静注射液)on Hippocampal N-methyl-D-aspartic Acid Receptors of Focal Cerebral Ischemia in Rats

Objective: To observe and elucidate the neuroprotective effect of Xingnaojing (XNJ) injection on hippocampal N-methyl-D-aspartic acid (NMDA) receptors of focal cerebral ischemia in rats. Methods: Cerebral ischemia was established by occluding the middle cerebral artery with an intraluminal suture technique in rats. Neurological deficit score, infarct volume and quantity of NMDA receptors were estimated in all groups and compared. Results: After being treated with XNJ, the score decreased in the initial 6 hours and infarct volume decreased in 24 hours. And within 24 hours, the quantity of NMDA receptors obviously decreased compared with the model group (P<0. 01) It indicated that XNJ could ameliorate neurological behavior of middle cerebral artery occlusion rats and down-regulate the expression of hippocampal NMDA receptors. Conclusion: The neuroprotective effect of XNJ on focal cerebral ischemia is possibly related to down-regulating the expression of NMDA receptors in rats.

Microwave-Assisted Synthesis of Poly(Aspartic Acid-Itaconic Acid) Copolymer and Its Characterization

Poly(aspartic acid-itaconic acid) copolymer was synthesized from aspartic acid(Asp) and itaconic acid(Ita) under microwave irradiation. The effects of microwave power, microwave irradiation time, molar ratio of itaconic acid and aspartic acid, catalyst type, catalyst and organic solvent content on copolymer yield, and the performance for inhibition of CaCO_3 fouling were investigated. It was found that the product yield achieved a highest record of 95% when the amount of catalyst Na H_2PO_4 was 0.012 mol, the amount of organic solvent propylene carbonate was 16 m L, the molar ratio of Asp/Ita was 3:1, the microwave output power was 1200 W and the irradiation time was 5.5 min. And the product performance for inhibition of calcium carbonate also reached a highest value of 94.38%. Structural characterization of the product showed that the product was the aspartic acid-itaconic acid copolymer.

Effects of Exogenous Amino Acids on the Contents of Amino Acids in Tobacco Leaves

The effect of three amino acids on the growth of flue-cured tobacco was studied with water culture. The results showed that the three amino acids improved the growth of flue-cured tobacco and increased the contents of chlorophyll a, chlorophyll b and carotenoid in tobacco. At the same time, the activities of NR (nitrate reductase), INV(invertase) and root growth activity were also significantly enhanced. The exogenous glutamic, aspartate and phenylalanine all increased the amino acid contents of tobacco leaves. Of these three amino acids, glutamic had the greatest effect, the next was aspartate, and phenylalanine had the least effect. These three amino acids all had significantly increased the accumulation of amino acids in the leaves of individual plants of tobacco; and the magnitude of accumulation indicated aspartate > glutamic > phenylalanine.

Gamma-aminobutyric acid A receptor and N-methyl-D-aspartate receptor subunit expression in rat spiral ganglion neurons

BACKGROUND： Gamma-aminobutyric acid A （GABAA） and N-methyl-D-aspartate （NMDA） receptors are significant receptors in the central nervous system. An understanding of GABAA and NMDA receptor expression in spiral ganglion neurons （SGN） provides information for the functional role of these receptors in the auditory system. OBJECTIVE： To investigate mRNA expression of GABAA receptor （GABAAR） and NMDA receptor （NMDAR） subunits in the rat SGN. DESIGN, TIME AND SETTING： This in vitro, molecular biological study was performed at the Laboratory of Otolaryngology-Head and Neck Surgery, Guangxi Medical University, China from July 2007 to May 2008. MATERIALS： Reverse Transcriptase Kit and Taq DNA polymerase were purchased from Fermentas Burlington, ON, Canada; GABAAR and NMDAR primers were purchased from Shanghai Sangon, Shanghai, China. METHODS： SGN from 3-5 day postnatal Wistar rats was collected for primary cultures, mRNA expression of GABAAR and NMDAR subunits in the SGN was determined by reverse transcription polymerase chain reaction. MAIN OUTCOME MEASURES： Expression levels of GABAAR and NMDAR subunits were determined by quantitative analysis. RESULTS： GABAAR subunits （αl 6, β1 3, and y1 3） and NMDAR subunits （NR1, NR2A, NR2B, NR2C, NR2D, NR3A, and NR3B） were detected in the SGN. In α subunit genes of GABAAR, α1 and α3 expression was similar （P 〉 0.05） and greater than the other subunits. Of the β subunit genes, β1 subunit mRNA levels were greater than β2 and β3. Of the y subunit genes, y2 subunit mRNA levels were greater than y1 and y3. NR1 mRNA expression was the greatest of NMDAR subunits. CONCLUSION： GABAAR subunits （α1 6, β1-3, and y1-3） and NMDAR subunits （NR1, NR2A, NR2B, NR2C, NR2D, NR3A, and NR3B） were expressed in the rat SGN. Through comparison of GABAAR and NMDAR subunit expression, possible GABAAR combinations, as well as highly expressed subunit combinations, were estimated, which provided information for pharmacological and electrophysiological characteristics of GABAAR in the auditory system.

EFFECTS OF DDT AND BHC ON AMINO ACID CONTENT AND ITS VARIETIES IN CHLORELLA VULGARISBEU. AND CLADOPHORA SP.

In Chlorella vulgaris Beg. and Cladophora sp. treated with different concentrations of r-BHC and p,p-DDT, the protein and free amino acid content in both were higher than those in the controls, and the free amino acid content was even higher than the protein amino acid content.

PREPARATION OF N－t－BUTYLOXYCARBONYL－O~α－9－FLUORENYLMETHYL ESTER OF ASPARTIC ACID

The preparation of the a carboxyl 9-fluorenylmethyl(FM) ester of Boc-aspartic acid is described.This new protected amino acid linked to the polymeric support by βcarboxyl group offers a convenient strategy for the synthesis of head-to-tail cyclopeptides while the peptides remained attached to the polymeric support.