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PubMed1980

Effects of 2-deoxy D-glucose and other sugar analogues on acid production from sugars by human dental plaque bacteria.

Solutions (10-25 microM) of D-glucose, N-acetyl-D-glucosamine, D-fructose, sucrose, maltose, lactose and maltotriose were readily metabolised to acid (140-250 mumol H+ wet g-1h-1) by anaerobic suspensions of fresh plaque at pH 7.5. D-Mannose, D-galactose, D-glucosamine and trehalose were broken down more slowly (35-115 mumol H+ wet g-1h-1). Inhibition of this acid production occurred on adding excess amounts of 2-deoxy-D-glucose or 5-thio-D-glucose. Similarly, excess amounts of cellobiose specifically inhibited acid liberation from lactose. No acid production was detected from a number of other sugars and sugar derivatives, some of which may be useful sucrose substitutes.

Adult↗
PubMed1984

Automatic amino acid and sugar analysis of glycoproteins.

Amino acid analyzers were used for complete analyses of glycoproteins. The methods of analysis used were cation-exchange chromatography for amino acids, phosphoamino acids and amino sugars with ninhydrin as reagent, and anion-exchange chromatography for neutral sugars with copper Bicinchoninate as reagent. A separate program was developed for the analysis of charged sugar components, N-acetylneuraminic acid and amino sugars in one chromatogram. The possibility of detection of radioactively labelled components is also demonstrated. The detection limits and possibilities for column and reactor switches are discussed.

Amino Acids↗
PubMed2024

Transcriptional landscape and dynamics involved in sugar and acid accumulation during apple fruit development.

In fleshy fruit, sugars and acids are central components of fruit flavor and quality. To date, the mechanisms underlying transcriptional regulation of sugar and acid during fruit development remain largely unknown. Here, we combined ATAC-seq with RNA-seq to investigate the genome-wide chromatin accessibility and to identify putative transcription factors related to sugar and acid accumulation during apple (Malus domestica) fruit development. By integrating the differentially accessible regions and differentially expressed genes, we generated a global data set of promoter-accessibility and expression-increased genes. Using this strategy, we constructed a transcriptional regulatory network enabling screening for key transcription factors and target genes involved in sugar and acid accumulation. Among these transcription factors, 5 fruit-specific DNA binding with one finger genes were selected to confirm their regulatory effects, and our results showed that they could affect sugar or acid concentration by regulating the expression of sugar or acid metabolism-related genes in apple fruits. Our transcriptional regulatory network provides a suitable platform to identify candidate genes that control sugar and acid accumulation. Meanwhile, our data set will aid in analyzing other characteristics of apple fruit that have not been illuminated previously. Overall, these findings support a better understanding of the regulatory dynamics during apple fruit development and lay a foundation for quality improvement of apple.

Malus↗
PubMed1992

Chemical composition of Litomosoides carinii microfilarial sheaths.

Litomosoides carinii microfilariae were exsheathed by freezing and thawing, and the sheaths were separated by filtration. Samples of pure sheaths thus obtained were hydrolyzed, methanolyzed or oxidized with nitric acid under pressure at 300 degrees C, respectively, and were analyzed for amino acids, sugars, fatty acids or for metal ions and phosphorus. Almost 75% of the sheath dry weight could thus be accounted for. Amino acids (55 weight %) were the major constituents, and amongst these glutamine and proline (approximately 11% each). The detection of 2% cysteine/cystine indicated the possible presence of disulfide crosslinks. Besides amino acids, approximately 8% of sugars--roughly equimolar amounts of (N-acetyl)galactosamine and uronic acids--1.5% of monovalent cations (Na+ and K+) and 9.5% of phosphate were detected. No appreciable amounts of fatty acids, neutral sugars, neuraminic acid, or (N-acetyl)glucosamine (i.e. no chitin) were found.

Amino Acids↗
PubMed2004

Acrylamide in French fries: influence of free amino acids and sugars.

The free amino acid profile and sugar (fructose, glucose, and sucrose) composition were determined in potato samples selected to give a large range of variation (a total of 66 samples). From these samples French fries were produced in a laboratory-scale simulation of an industrial process followed by a finish fry at 180 degrees C for 3.5 min using a restaurant fryer. The final product was blast frozen and analyzed for acrylamide. Acrylamide was detected in all samples, but its concentration varied significantly from 50 to 1800 ng/g. For isotope dilution (13C3) acrylamide analysis, samples were extracted with water, cleaned up on HLB Oasis polymeric and Accucat mixed mode anion and cation exchange SPE columns, and analyzed by LC-MS/MS. Statistical analysis of the data indicates that the effect of sugars and asparagine on the concentration of acrylamide in French fries is positive and significant (p < 0.001). It appears that one of the ways acrylamide formation in French fries can be effectively controlled is by the use of raw products with low sugar (and to a lesser degree, asparagine) content.

Acrylamide↗
PubMed2000

Capillary electrophoresis for the determination of major amino acids and sugars in foliage: application to the nitrogen nutrition of Sclerophyllous species.

Amino acids and sugars are probably the most commonly measured solutes in plant fluids and tissue extracts. Chromatographic techniques used for the measurement of such solutes require complex derivatization procedures, analysis times are long and separate analyses are required for sugars and amino acids. Two methods were developed for the analysis of underivatized sugars and amino acids by capillary electrophoresis (CE). Separation of a range of sugars and amino acids was achieved in under 30 min, with good reproducibility and linearity. In general, there was close agreement between amino acid analyses by CE and HPLC with post-column derivatization. An alternative, more rapid method was optimized for the common neutral sugars. Separation of a mixture of fructose, glucose, sucrose, and fucose (internal standard) was achieved in less than 5 min. How the source of N applied (nitrate or ammonium) and its concentration (8.0 or 0.5 mM) affects the amino acid and sugar composition of leaves from Banksia grandis Willd. and Hakea prostrata R. Br. was investigated. The amino acid pool of Banksia and Hakea were dominated by seven amino acids (aspartic acid, glutamic acid, asparagine, glutamine, serine, proline, and arginine). Of these, asparagaine and glutamine dominated at low N-supply, whereas at high N-supply the concentration of arginine increased and dominated amino-N. Plants grown with nitrate had a greater concentration of proline relative to plants with ammonium. In Banksia the concentration of amides was greatest and arginine least with a nitrate N-source, whereas in Hakea amides were least and arginine greatest with nitrate N-source. The concentration of sugars was greater in Banksia than Hakea and in both species at greater N-supply.

Amino Acids↗
PubMed2003

Cyclic homooligomers of furanoid sugar amino acids.

Cyclic homooligomers of mannose-derived furanoid sugar amino acid 1 [H-Maa(Bn(2))-OH] were synthesized by using BOP reagent in the presence of DIPEA under dilute conditions that converted the sugar amino acid monomer directly into its cyclic homooligomers 3a and 4a. The glucose-based sugar amino acid 2 [H-Gaa(Bn(2))-OH] under the same reaction conditions gave a bicyclic lactam 5a as the major product. Cyclic homooligomers of 2 were prepared by cyclizing their linear precursors 6 and 7 leading to the formation of cyclic peptides 8a and 9a, respectively. Conformational analysis by NMR and constrained MD studies revealed that all the cyclic products, 3, 4, 8, and 9, had symmetrical structures. The deprotected cyclic trimer of Maa 3b displayed a conformation in which all the C=O and the N-H bonds of the molecule point in opposite directions. In the deprotected cyclic tetramer of Maa 4b, the COs and NHs were in the plane of the ring with the former pointing to outside and the latter inside the ring. The structure of the cyclic Gaa dimer 8b displayed an unusual six-membered intramolecular hydrogen bond between NH(i)() --> C3-O(i)()(-)(1) and a syn orientation between the C2-H and CO. In this molecule, the C2-hydrogens and the COs can be seen on one side of the ring while the NHs point to the other side. Addition of the bicyclic lactam 5b resulted in the influx of Na(+) ions across the lipid bilayer leading to the dissipation of valinomycin-mediated K(+) diffusion potential.

Amino Acids, Neutral↗
PubMed1987

Assimilate Unloading from Maize (Zea mays L.) Pedicel Tissues : II. Effects of Chemical Agents on Sugar, Amino Acid, and C-Assimilate Unloading.

Sugar, amino acid, and (14)C-assimilate release from attached maize (Zea mays L.) pedicels was studied following treatment with several chemical inhibitors. In the absence of these agents, sugar release was nearly linear over a 7-hour period. At least 13 amino acids were released with glutamine comprising over 30% of the total. Release was not affected by potassium concentration, 10-minute pretreatments with p-chloromercuribenzene sulfonic acid (PCMBS) or dithiothreitol, and low concentrations of CaCl(2). Three hours or more exposure to PCMBS, dinitrophenol, N-ethylmaleimide, or 2,4,6-trinitrobenzene sulfonic acid strongly inhibited (14)C-assimilate, sugar, and amino acid release from the pedicel. These treatments also reduced (14)C-assimilate movement into the kernel bases. It is, therefore, likely that reduced unloading, caused by these relatively long-term exposures to chemical inhibitors, was related to reduced translocation of assimilates into treated kernels. Whether this effect is due to disruption of kernel metabolism and sieve element function or reduced assimilate unloading and subsequent accumulation of unlabeled assimilates within the pedicel tissues cannot be determined at this time.

Journal Article↗
PubMed2004

Formation of a stable 14-helix in short oligomers of furanoid cis-beta-sugar-amino acid.

Oligomers of a new class of sugar amino acids (SAA) using a xylofuranoic acid has been shown to generate a robust 14-helix. The design involved the use of xylofuranose with a cis arrangement between the amine and carboxyl groups to promote the adoption of a 14-helix instead of a mixed 12/10-helix observed in a sugar oligomer using a ribofuranoic acid and beta-Ala. The observation of a stable right-handed 14-helix in a cis-SAA is unprecedented.

Amino Acids↗
PubMed2006

Synthesis of a galacto-configured C-ketoside-based gamma-sugar-amino acid and its use in peptide coupling reactions.

Gamma-sugar-amino acid analogues in the form of C-ketosides can be prepared in 5-6 steps starting from D-galactono-1,5-lactone. The key step in the synthesis is the trimethylsilyl trifluoromethanesulfonate (TMSOTf) promoted C-glycosylation of 2-deoxy-3-ulopyranosonates with trimethylsilyl cyanide. Hydrogenation of the resulting beta-cyano esters provides C-ketoside-based gamma-sugar-amino acids that serve as building blocks for the synthesis of unnatural neoglycopeptides.

Amino Acids↗
PubMed2005

Synthesis of orthogonally protected cyclic homooligomers from sugar amino acids.

Two new families of orthogonally protected cyclic homooligomers with two to four sugar units were synthesized from pyranoid sugar amino acids. Cyclic oligomers composed of amide-linked sugar amino acids (1-3) were prepared by cyclization of linear oligomers of the novel orthogonally protected pyranoid sugar amino acid 12 using a solution-phase coupling method. These orthogonally protected cyclic molecules can be selectively or fully deprotected, affording the macrocycles ready to further functionalization. The straightforward reduction of the amide bonds in the cyclic oligomers 1-3 gave the corresponding amine-linked macrocycles 4-6. This kind of amine-linked carbohydrate-based cyclic oligomer has never been reported before. These flexible molecular receptors could be studied as molecular hosts for molecular, cationic, and anionic recognition. Conformational analysis by molecular modeling (AM1) showed that all of the deprotected cyclic trimers and tetramers preferred a (4)C(1) chair conformation with oxygen atoms of the sugar ring located on the interior of the cavity and the secondary hydroxyl groups outward. In the amide-linked macrocycles, all of the amide bonds are in s-trans conformation. The estimated size of the internal cavity is about 4.5 A for the cyclic trimer and 6.9 A for the cyclic tetramer. The amine-linked macrocycles displayed similar conformational behavior with a slight decrease in internal cavity.

Amino Acids↗
PubMed2001

Cyclic homooligomers from sugar amino acids: synthesis, conformational analysis, and significance.

Sugar amino acids (SAAs) were designed as new building blocks carrying an amino group and a carboxyl group on a carbohydrate scaffold. By exploiting standard solid- and solution-phase coupling procedures, linear and cyclic homooligomers containing glucosyluronic acid methylamine (Gum) were synthesized. We achieved a high yield and a very short coupling time for the oligomerization and cyclization of sequences encompassing two, three, four, and six Gum units. The synthesis of cyclic oligomers containing only SAAs as repetitive units has not been reported before. The conformational preferences in aqueous solution of the cyclic derivatives and their applications as potential host molecules are described herein. Benzoic acid and p-nitrophenol were chosen as model guest molecules to study the formation of cyclodextrin-like inclusion complexes. The complexation behavior of the cyclic hexamer was proved from three different points of view: chemical shifts, longitudinal relaxations (T(1)), and diffusion coefficients. All of them showed different values for host and guest molecules measured independently and in the presence of each other.

Amino Acids↗
PubMed1978

Developmental aspects of maleic acid-induced inhibition of sugar and amino acid transport in the rat renal tubule.

The transport of alpha-aminoisobutyric acid and alpha-methyl-d-glucoside by isolated tubules from Sprague-Dawley rats at different stages of development follows a separate age-dependent pattern for each substrate. The effects of 6 M maleic acid on transport processes differ for amino acids and sugars and become manifest at distinct points during development. Maximum inhibition by maleic acid occurs at a time subsequent to maturity of these transport systems. In an effort to explain these transport phenomena, the uptake and metabolism of 14C-labeled maleic acid by the newborn or adult renal tubule was studied, showing significant binding by the tubule membrane, penetration of the cell by diffusion, and no conversion to 14CO2. Maleic acid has no demonstrable effect on the membrane-associated enzymes which are thought to play a role in the transport of small molecules.

Age Factors↗
PubMed2000

Biochemical and microbial changes during the storage of minimally processed cantaloupe.

The effect of storage time on pH, titratable acidity, degrees Brix, organic acids, sugars, amino acids, and color of minimally processed cantaloupe melon (Cucumis melo L. var. reticulatus Naud. cv. Mission) was determined at 4 degrees C and 20 degrees C. Changes in most of the biochemical parameters with storage time were relatively slow at the lower temperature. At 20 degrees C, a 17% loss in soluble solids and a 2-fold increase in acidity occurred after 2 days. Organic acid content also increased considerably with time at this temperature as a result of the production of lactic acid. Oxalic, citric, malic, and succinic acids were the organic acids, and glucose, fructose, and sucrose were the sugars present in the freshly cut cantaloupe. Malic acid concentration decreased concurrently with lactic acid production indicating the possible involvement of anaerobic malo-lactic fermentation along with sugar utilization by lactic acid bacteria. The effect of storage on microbial growth was determined at 4, 10, and 20 degrees C. Gram-negative stained rods grew at a slower rate at 4 degrees C and 10 degrees C than the Gram-positive mesophilic bacteria that dominated microorganism growth at 20 degrees C. Eighteen amino acids were identified in fresh cantaloupe: aspartic acid, glutamic acid, asparagine, serine, glutamine, glycine, histidine, arginine, threonine, alanine, proline, tyrosine, valine, methionine, isoleucine, leucine, phenyl alanine, and lysine. The dominant amino acids were aspartic acid, glutamic acid, arginine, and alanine. Total amino acid content decreased rapidly at 20 degrees C, but only a slight decrease occurred at 4 degrees C after prolonged storage. Changes in lightness (L), chroma, and hue at both temperatures indicate the absence of browning reactions. The results indicate the potential use of lactic acid and lactic acid bacteria as quality control markers in minimally processed fruits.

Bacteria↗
PubMed2002

Enzymatic synthesis of sugar amino acid esters in organic solvents.

The enzymatic synthesis of sugar amino acid esters in polar organic solvents was studied using surfactant-enzyme complexes, which were previously developed as a highly active biocatalyst in organic solvents. Of the several lipases and proteases tested, the surfactant-subtilisin complex exhibited the highest synthetic activity in pyridine. The amino acid was regioselectively introduced at the C-6 position of d-glucose and at the C-6' of maltose by the surfactant-subtilisin complex. This biocatalyst was found to effectively catalyze the synthesis of various sugar amino acid esters in a polar organic solvent.

Journal Article↗
PubMed1978

High-performance liquid chromatographic investigation of the amino acid, amino sugar and neutral sugar content in glycoproteins.

A methods for the simultaneous separation and determination of amino acids, amino sugars and neutral carbohydrates is described. Stepwise elution systems with sodium citrate and borate buffers have developed for the ion-exchange liquid chromatographic separation of amino acids and sugars, using 8-micrometer particle size resins and the Stein and Moore and orcinol colorimetric method for detection. With the aid of this system, the direct quantitative comparison of sugars and amino acids by liquid chromatography becomes possible for the first time.

Amino Acids↗
PubMed1979

Effects of Mn-deficit feeding to ewes on certain amino acids and sugars in cartilage of their newborn lambs.

The distribution of amino acid, amino sugar, and uronic acid in the epiphyseal cartilage of newborn lambs were examined to determine the influence of manganese (Mn) deficiency. Throughout the gestational period, one group (group I) of eight pregnant ewes was given a ration containing 60 mg of Mn/kg of feed and a second group (group II) of eight ewes was given a ration containing 5 mg of Mn/kg of feed. The neonatal lambs were killed, and the epiphyseal plates from various bones in the thoracic limb were removed and analyzed for glucosamine, galactosamine, uronic acid, and 17 amino acids. Concentrations of uronic acid and of the sulphur amino acids (methionine not significant, P greater than 0.05) were larger in the cartilage from the lambs born of group I ewes (60 mg of Mn/kg of ration) than in the cartilage from those of the Group II ewes (Mn deficiency). A tendency for higher hexosamine values was observed in the organic matrix of the group I lambs than of the group II lambs. However, concentrations of serine, histidine, and lysine were higher in the cartilage from group II lambs (Mn deficiency). Thus, the role of Mn in the prevention of joint abnormalities may be its influence on the mucopolysaccharide and protein composition of the epiphyseal plate.

Amino Acids↗
PubMed1999

Synthesis of sugar fatty acid esters by modified lipase.

A simple synthesis of sugar fatty acid esters was developed in a nonaqueous solution using lipase modified by synthetic detergent. Esterification of sugar was accelerated by continuous removal of water from the reaction mixture with a molecular sieve. When glucose and palmitic acid (1:1 by mole) were used as the starting substrates, more than 90% of glucose was converted to its ester in this system. The resultant product was 6-O-palmitoylglucose. Other mono- or disaccharides were also esterified by the modified lipase with high yield. It was shown that the modified lipase might act as a catalyst for the synthesis of sugar fatty acid esters.

Carbohydrates↗