scholarly journals Synthesis of Dianionic and Trianionic Chiral, Chelating Ligands Based on Amino Acids

2008 ◽  
Vol 61 (4) ◽  
pp. 297
Author(s):  
Madeleine Schultz ◽  
Jakov Kulis ◽  
Julie Murison ◽  
Genevieve W. Andrews
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Nitrilotriacetic Acid ◽  
Solution Phase ◽  
Chelating Ligands ◽  
Bidentate Ligands ◽  
Synthetic Route ◽  
Tridentate Ligands ◽  
Amide Coupling

The synthesis of two new families of amino acid-containing chiral ligands, based on methyliminodiacetic acid and nitrilotriacetic acid cores, has been accomplished using a simple protection, solution-phase amide coupling, and deprotection strategy. The amino acids glycine, leucine, aspartic acid, and phenylalanine were used to demonstrate the versatility of the synthetic route, and that no epimerization occurs. The tridentate ligands bear C3 symmetry, whereas the bidentate ligands have C1 symmetry.

scholarly journals Transforming growth factor alpha: mutation of aspartic acid 47 and leucine 48 results in different biological activities.

1988 ◽  
Vol 8 (3) ◽  
pp. 1247-1252 ◽  
Author(s):  
E Lazar ◽  
S Watanabe ◽  
S Dalton ◽  
M B Sporn
Keyword(s):  
Amino Acids ◽  
Biological Activity ◽  
Amino Acid ◽  
Growth Factor ◽  
Aspartic Acid ◽  
Transforming Growth Factor ◽  
Biologically Active ◽  
Single Amino Acid ◽  
Transforming Growth Factor Alpha ◽  
Factor Alpha

To study the relationship between the primary structure of transforming growth factor alpha (TGF-alpha) and some of its functional properties (competition with epidermal growth factor (EGF) for binding to the EGF receptor and induction of anchorage-independent growth), we introduced single amino acid mutations into the sequence for the fully processed, 50-amino-acid human TGF-alpha. The wild-type and mutant proteins were expressed in a vector by using a yeast alpha mating pheromone promoter. Mutations of two amino acids that are conserved in the family of the EGF-like peptides and are located in the carboxy-terminal part of TGF-alpha resulted in different biological effects. When aspartic acid 47 was mutated to alanine or asparagine, biological activity was retained; in contrast, substitutions of this residue with serine or glutamic acid generated mutants with reduced binding and colony-forming capacities. When leucine 48 was mutated to alanine, a complete loss of binding and colony-forming abilities resulted; mutation of leucine 48 to isoleucine or methionine resulted in very low activities. Our data suggest that these two adjacent conserved amino acids in positions 47 and 48 play different roles in defining the structure and/or biological activity of TGF-alpha and that the carboxy terminus of TGF-alpha is involved in interactions with cellular TGF-alpha receptors. The side chain of leucine 48 appears to be crucial either indirectly in determining the biologically active conformation of TGF-alpha or directly in the molecular recognition of TGF-alpha by its receptor.

scholarly journals The effect of Cladophora glomerata exudates on the amino acid composition of Cladophora fracta and Rhizoclonium sp.

2019 ◽  
Vol 17 (1) ◽  
pp. 313-324 ◽  
Author(s):  
Marta Pikosz ◽  
Joanna Czerwik-Marcinkowska ◽  
Beata Messyasz
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Amino Acid Composition ◽  
Aspartic Acid ◽  
Defense Mechanisms ◽  
Chemical Stress ◽  
Cladophora Glomerata ◽  
Adaptation To Stress ◽  
Filamentous Green Algae

AbstractFilamentous green algae (FGA) frequently forms dense mats which can be either mono- or polyspecies. While various defense mechanisms of competition in algae are known, little is known about the interactions between different species of FGA. An experiment in controlled laboratory conditions was conducted to gather data on the changes in amino acids (AA) concentrations in FGA species in the presence of exudates from different other species. The aim of the present study was to identify the AA whose concentrations showed significant changes and to assess if the changes could be adaptation to stress conditions. The major constituents of the AA pool in Cladophora glomerata, C. fracta and Rhizoclonium sp. were Glutamic acid (Glu), Aspartic acid (Asp) and Leucine (Leu). In response to chemical stress, that is the increasing presence of exudates, a significant increase in the concentrations Proline (Pro) and Tryptophan (Trp) was noted. The increase in Proline levels was observed in C. fracta and Rhizoclonium in response to chemical stress induced by C. glomerata exudates. As the concentration of exudates increased in the medium, there was a progressive shift in the pattern of AA group in FGA.

Effect of Salinity on Photosynthetic 14CO2 Fixation and Amino Acid Pools of Bellerochea yucatanensis (v. Stosch) and Thalassiosira rotula (Meunier)

1985 ◽  
Vol 40 (7-8) ◽  
pp. 527-530
Author(s):  
Günter Döhler ◽  
Joachim Zink
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Marine Diatoms ◽  
14Co2 Fixation ◽  
Low Salt ◽  
Photosynthetic Products ◽  
Sugar Phosphates ◽  
Total Amino Acids

Abstract The marine diatoms Bellerochea yucatanensis and Thalassiosira rotula were grown at different salinities (20/25, 35, and 40/45‰ salinity (S), respectively) under normal air (0.035 vol.% CO2). No significant variations in the percentage of gross photosynthetic products (e.g. total amino acids, sugar phosphates) were found as a function of salinity during growth. The bulk of the soluble 14C-radioactivity was detected in amino acids. 14C-labelling of glutamine increased markedly with salinity. Low salt - grown algae are characterized by enhanced amino acid pools, mainly of aspartic acid, asparagine and glutamine. It was found that the tested amino acids are not involved in osmoregulation.

Self-healing hydrogels triggered by amino acids

2016 ◽  
Vol 3 (12) ◽  
pp. 1699-1704 ◽  
Author(s):  
Nicola Zanna ◽  
Andrea Merlettini ◽  
Claudia Tomasini
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Chemical Properties ◽  
Aromatic Amino Acids ◽  
Self Healing ◽  
Acidic Amino Acid ◽  
Basic Amino Acids

Nine amino acids with different chemical properties have been chosen to promote the formation of hydrogels based on the bolamphiphilic gelator A: three basic amino acids (arginine, histidine and lysine), one acidic amino acid (aspartic acid), two neutral aliphatic amino acids (alanine and serine) and three neutral aromatic amino acids (phenylalanine, tyrosine and tryptophan).

scholarly journals Amino Acid Metabolism in Friedreich's Ataxia

1976 ◽  
Vol 3 (4) ◽  
pp. 373-378 ◽  
Author(s):  
B. Lemieux ◽  
A. Barbeau ◽  
V. Beroniade ◽  
D. Shapcott ◽  
G. Breton ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Plasma Levels ◽  
Genetic Defect ◽  
Friedreich’S Ataxia ◽  
Friedreich's Ataxia ◽  
Physiological Importance ◽  
And Control ◽  
Csf Concentration

SUMMARY:A study of amino acids determined by sequential Multi-sample Amino Acid Automatic Analyzer in plasma, urine and cerebrospinal fluid (CSF) in patients with Friedreich's ataxia and control subjects has revealed a number of mathematically significant variations from normal. Of practical physiological importance are the following: a high urinary excretion of alanine with slightly elevated plasma levels; a low plasma and CSF concentration of aspartic acid in the resence of normal urinary values and finally a low CSF concentration of taurine accompanied by normal plasma levels, but elevated urinary output and renal clearance rates. We postulate that the modifications in alanine and aspartic acid are less specific and probably secondary, but there could be a genetic defect in the membrane transport of taurine and the other β-amino acids in Friedreich's ataxia.

Amino Acid Metabolism in Plants. III. Purification and Some Properties of a Multispecific Aminotransferase Isolated from Bushbean Seedlings (Phaseolus vulgaris L.)

1972 ◽  
Vol 50 (7) ◽  
pp. 813-829 ◽  
Author(s):  
J. C. Forest ◽  
F. Wightman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Aspartate Aminotransferase ◽  
Soluble Protein ◽  
Specific Activity ◽  
Aromatic Amino Acids ◽  
Total Activity ◽  
Aminotransferase Activity ◽  
Aromatic Aminotransferase

The development of aromatic aminotransferase activity was examined in cotyledons, roots, and shoots of bushbean seedlings growing under light or dark conditions for the first 2 weeks after germination. All three aromatic amino acid – α-ketoglutarate aminotransferase activities were found to have similar patterns of development in comparable organs grown under the two environmental conditions, and the changes in levels of activity appeared unrelated to variations in the endogenous amounts of free aromatic amino acids in the organs of these seedlings. The highest total activity for all three transamination reactions was found in the shoots of light-grown seedlings after 14 days, whereas the aminotransferases showing highest specific activity were found in roots of both kinds of seedlings after 8 days of growth. The intracellular distribution of the three aromatic aminotransferase activities and of aspartate aminotransferase activity was investigated by differential centrifugation of root homogenates. Only a total of 10% of these two activities was found in the two particulate fractions; the soluble protein in the final supernatant fraction accounted for almost 90% of the total aromatic and aspartate aminotransferase activities.The aromatic aminotransferase in the soluble protein fraction from seedling roots was purified about 600-fold by pH precipitation, ammonium sulfate fractionation, and Sephadex chromatography, and the recovery obtained was 30–35% based on total activity. It was observed that the specific activity for aspartate–α-ketoglutarate aminotransferase increased proportionally to the increase in aromatic aminotransferase activities during the different steps of purification. Gel electrophoresis of the purified fraction revealed only one protein band which corresponded to the product-specific stained band for the three aromatic aminotransferase activities assayed on other gels. The molecular weight of the purified aminotransferase was found to be about 128 000 daltons and its Stokes radius was calculated to be 43 ± 3 Å. The pH optima for the three aromatic aminotransferase activities and for aspartate aminotransferase activity were all found to be 8.5. The purified enzyme showed no specific requirement for pyridoxal phosphate and an examination of its amino acid substrate specificity revealed that it was able to catalyze transamination of L-aspartic acid, L-phenylalanine, L-tyrosine, and L-tryptophan when α-ketoglutarate was provided as amino group acceptor. The enzyme was also found to catalyze transamination of L-glutamic acid when oxaloacetate was used as amino group acceptor, but neither pyruvate nor glyoxylate were utilized as amino acceptors for transamination of any of the amino acids examined. The enzyme was found to catalyze transamination of aspartic acid with much greater velocity than its rate of reaction with any of the three aromatic amino acids, and the inclusion of aspartic acid in a reaction medium at equimolar concentration with any one of the three aromatic amino acids resulted in strong inhibition of the aromatic aminotransferase activity of the enzyme. All the evidence indicates that the soluble protein fraction purified from bushbean roots contained only one aminotransferase which was able to catalyze the transamination of five L-amino acids. The demonstration of the substrate multispeciftcity of this pure enzyme represents the first evidence for a multispecific aminotransferase in plants.

Growth responses of race 222 of Puccinia graminis tritici in defined media

1982 ◽  
Vol 28 (5) ◽  
pp. 486-492
Author(s):  
Hardev Singh ◽  
Inderjeet Sethi
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Axenic Culture ◽  
Puccinia Graminis ◽  
Growth Responses ◽  
Liquid Media ◽  
High Concentration ◽  
Puccinia Graminis Tritici ◽  
Defined Media

Aseptically produced uredospores of race 222 of Puccinia graminis tritici were seeded on defined liquid media containing Czapek's minerals, sucrose or glucose, and various combinations and concentrations of 19 amino acids and a tripeptide, glutathione. The cultures were incubated in the dark at 16–17 °C. A medium containing a high concentration of aspartic acid (5988 ppm), cysteine (557 ppm), and glutathione (1014 ppm) supported a profuse growth of the fungus in the form of floating white, fluffy, and vegetative colonies. A sulphur-containing amino acid appears to be essential for the axenic culture of the fungus.

Use-dependent block of excitatory amino acid currents in cultured neurons by ketamine

1987 ◽  
Vol 58 (2) ◽  
pp. 251-266 ◽  
Author(s):  
J. F. MacDonald ◽  
Z. Miljkovic ◽  
P. Pennefather
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Excitatory Amino Acids ◽  
Hippocampal Neurons ◽  
Excitatory Amino Acid ◽  
Outward Current ◽  
Bathing Solution ◽  
Wide Range ◽  
Repeated Applications

1. Mouse hippocampal neurons grown in dissociated cell culture were patch clamped using a whole cell voltage clamp (discontinuous switching clamp) technique. The currents generated by pressure applications of excitatory amino acids were studied over a wide range of holding potentials, and current-voltage curves were plotted. Excitatory amino acids that activated the N-methyl-D-aspartic acid (NMDA) receptor demonstrated some degree of desensitization with repeated applications, whereas the currents observed in response to kainic acid (KAI) did not. Desensitization could be minimized by keeping the frequency of application sufficiently low (i.e., less than 0.1 Hz). 2. The short-acting dissociative anaesthetic, ketamine (2–50 microM), selectively blocked L-aspartic acid (L-Asp), NMDA, and L-glutamic acid (L-Glu) currents while sparing those in response to KAI. Therefore, ketamine is a relatively selective blocker of the NMDA response versus that (those) activated by KAI. 3. The block by ketamine of excitatory amino acid currents is highly voltage dependent. Concentrations of ketamine that had little effect on outward current responses at depolarized potentials were quite effective at blocking inward current responses at hyperpolarized potentials. In contrast, DL-2-amino-5-phosphonovaleric acid (APV) was equally effective at blocking both inward and outward currents (voltage independent). The voltage dependence of ketamine (a positively charged molecule) could be accounted for if ketamine blocked the NMDA response by binding to a site that experienced 55% of the membrane field. 4. In the presence of ketamine, peak inward currents evoked by repeated applications of NMDA, L-Asp, or L-Glu progressively declined to a steady-state level of block (use-dependent block). This decrement occurred at frequencies much lower than those that were employed to demonstrate desensitization (in the absence of ketamine). Moving the membrane potential to depolarized values did not, in itself, relieve the ketamine block. However, if the appropriate excitatory amino acid (L-Asp, NMDA, L-Glu) was applied during the period of depolarization, a relief of the block could be demonstrated. No recovery from the blockade occurred with periods of rest (no amino acid application) as long as 5 min. Furthermore, no recovery was observed even when ketamine was washed out of the bathing solution until the appropriate agonist was applied. Thus recovery from blockade, like development of blockade, was use dependent.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Phosphorus (V) porphyrin diaxially substituted with Leu-enkephalin

2004 ◽  
Vol 2 (3) ◽  
pp. 446-455 ◽  
Author(s):  
Mariusz Gajewski ◽  
Leszek Czuchajowski
Keyword(s):  
Amino Acids ◽  
Photodynamic Therapy ◽  
Amino Acid ◽  
Biologically Active ◽  
Solution Phase ◽  
Terminal Amino Acid ◽  
Leucine Enkephalin ◽  
Potential Applications ◽  
Biologically Active Peptide ◽  
Terminal Amino

AbstractSynthesis of the first phosphorus (V) porphyrin-peptide conjugate was successfully accomplished. A biologically active peptide, leucine enkephalin, was constructed on the phosphorus atom of the 5,10,15,20-meso-tetraphenylporphinato dichlorophosphorus (V) chloride. The method involved solution phase peptide synthesis. The first C-terminal amino acid in the sequence of the peptide was axially attached to the porphyrin through a linker, 3-aminopropanol, and the remainder of leucine enkephalin was synthesized by subsequent additions of amino acids. Leucine enkephalin-P(V) porphyrin conjugate represents a new group of compounds, and its synthesis broadens potential applications of P(V) porphyrine, e.g. in photodynamic therapy.

scholarly journals Sequence of the N-terminal half of Bacillus amyloliquefaciens α-amylase

1980 ◽  
Vol 185 (2) ◽  
pp. 387-395 ◽  
Author(s):  
H Chung ◽  
F Friedberg
Keyword(s):  
Amino Acids ◽  
Bacillus Subtilis ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Primary Structure ◽  
Bacillus Amyloliquefaciens ◽  
Proteolytic Enzymes ◽  
Alpha Amylase ◽  
Sequence Determination ◽  
N Terminus

Bacillus amyloliquefaciens alpha-amylase (1,4-alpha-D-glucan glucanohydrolase. EC 3.2.1.1), which is commercially supplied as ‘Bacillus subtilis alpha-amylase’ does not cross-react immunologically with B. subtilis alpha-amylase. This enzyme (from B. amyloliquefaciens) was cleaved by treatment with CNBr into seven fragments. Peptide A was selected for sequence determination. It is the longest one, containing 185 amino acids (i.e. approx. 50% of the total molecule) and connects to the hexapeptide of the N-terminus. Its primary structure was aligned by use of various proteolytic enzymes. The sequence of amino acids 181-184 is identical with that of amino acids 14-17 of the alpha-amylase isolated from B. subtilis (except that amino acid 183 is asparagine rather than aspartic acid).

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