Biodegradation of copoly(L-aspartic acid/L-glutamic acid) in vitro

SummaryThis study compared the anti-platelet effect of Ac-RGDS-NH2 which is a peptide fragment from fibrinogen to Ac-RGES-NH2 in which the aspartic acid (D) of Ac-RGDS-NH2 has been replaced by glutamic acid (E). When Ac-RGDS-NH2 was infused intracoronary at concentrations of 100–400 mM, acute platelet dependent thrombus formation in the dog coronary artery was inhibited. However, infusion of Ac-RGES-NH2 intracoronary at similar concentrations to Ac-RGDS-NH2 failed to inhibit platelet dependent thrombus formation in the dog. Ac-RGDS-NH2 and Ac-RGES-NH2 were also tested for their ability to inhibit collagen-induced platelet aggregation in vitro. Ac-RGDS-NH2 elicited concentration-dependent inhibition of collagen-induced aggregation with no effect of Ac-RGES-NHz otr collagen-induced platelet aggregation. Thus, Ac-RGDS-NH2 is an effective antiplatelet agent after intracoronary administration in the dog and also inhibits collagen-induced platelet aggregation in vitro. Ac-RGDS-NH2 is a specific inhibitor of platelet aggregation as replacement of the aspartic acid in Ac-RGDS-NH2 with glutamic acid results in complete loss of biological activity.

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Amino acid content of rat renal cortex and the response to in vitro incubation

AJP Renal Physiology ◽

10.1152/ajprenal.1979.236.4.f398 ◽

1979 ◽

Vol 236 (4) ◽

pp. F398-F404

Author(s):

B. Blazer-Yost ◽

R. Reynolds ◽

S. Segal

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Glutamic Acid ◽

Aspartic Acid ◽

Room Temperature ◽

Renal Cortex ◽

Adult Tissue ◽

Fresh Tissue ◽

Cortical Slices

The concentration of aspartic acid, threonine, serine, glycine, and alanine is significantly higher in newborn rat renal cortex than in the adult tissue, while phenylalanine and histidine are higher in the adult. When adult cortical slices are placed in bicarbonate buffer at room temperature for 20 min there is a 30-60% decrease in the levels of all amino acids except for lysine, which is slightly higher, and methionine and serine, which do not change. Under the same conditions, newborn cortical slices reveal a similar decrease in only glycine, tyrosine, histidine, and the branched-chain amino acids. On subsequent in vitro incubation of the cortical slices at 37 degrees C for 120 min the concentrations in adult tissue remain at the lower values observed on removal from buffer at room temperature except that glutamic acid, glycine, and lysine levels decrease further and serine increases to the concentration found in fresh tissue. Newborn tissue when incubated at 37 degrees C for 120 min shows amino acid concentrations comparable to unincubated fresh tissue for all except aspartic acid, glutamic acid, serine, and phenylalanine, which reach levels higher than unincubated tissue. The ability of newborn tissue to maintain amino acid pools may play a role in the enhanced transport of some amino acids resulting from preincubation at 37 degrees C (Reynolds et al. Science 184: 68-69, 1974; Reynolds and Segal, Biochim. Biophys. Acta 406: 513-525, 1976).

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Uptake of Dipeptides Containing Basic and Acidic Amino Acids by Rat Small Intestine in Vitro

Clinical Science ◽

10.1042/cs0430823 ◽

1972 ◽

Vol 43 (6) ◽

pp. 823-837 ◽

Cited By ~ 42

Author(s):

D. Burston ◽

Jill M. Addison ◽

D. M. Matthews

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Glutamic Acid ◽

Aspartic Acid ◽

Free Amino Acids ◽

Free Amino ◽

Tissue Uptake ◽

Acidic Amino Acids ◽

Hydrolysis Of

1. The characteristics of transport and hydrolysis of twenty-two dipeptides containing basic and acidic amino acids by rat ileal rings were investigated in vitro. The peptides included combinations of basic and neutral, basic and basic, basic and acidic, acidic and acidic, and acidic and neutral amino acids. 2. All peptides studied were removed intact from the bulk phase of the incubation medium, though, in general, only free amino acids appeared in the tissue. Uptake of one or both constituent amino acids was greater from the peptide than from the equivalent amino acid or amino acid mixture in the case of at least one peptide from each group and in eighteen of the twenty-two peptides studied. In general, there was no relationship between the extent of uptake of amino acids from peptides and the extent of their hydrolysis by the system. The results support the hypothesis that there is more than one mode of uptake of amino acids from peptides. 3. Hydrolysis of γ-glutamyl-l-glutamic acid by intact intestine or intestinal homogenate was slight, and intact peptide was taken up by the tissue. Uptake of free glutamic acid from this peptide was poor. Comparison of γ-glutamyl-l-glutamic acid with three other slowly hydrolysed dipeptides, glycyl-d-valine, sarcosylglycine and glycylsarcosine, suggested that all four were transported into the mucosal cells and hydrolysed intracellularly. The results indicate that the presence of a γ-linkage or a d-amino acid, or methylation of the free amino group as in sarcosylglycine, impair both transport and hydrolysis of peptide, but that attachment of a methyl group to the N of the peptide bond, as in glycylsarcosine, impairs hydrolysis but has no effect on peptide transport. 4. l-Aspartic acid and l-glutamic acid were extensively transaminated by the intestine, whether presented as free amino acids or in peptides. Evidence was obtained suggesting that production of alanine from aspartic acid resulted from direct transamination of aspartic acid with pyruvic acid, rather than from a sequence of two reactions involving aspartate and alanine aminotransferases. 5. The results show that more rapid uptake of amino acids from peptides than from free amino acids is not confined to peptides made up of neutral amino acids, and probably occurs with many small peptides. Uptake of lysine and the dicarboxylic amino acids, which are particularly slowly absorbed from free solution, was much greater from several dipeptides than from the free amino acids. The results suggest the importance of mucosal peptide uptake in protein absorption.

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Effects of amino acids on the development of spikelets in cultured tassels of Zea mays

Canadian Journal of Botany ◽

10.1139/b89-177 ◽

1989 ◽

Vol 67 (5) ◽

pp. 1331-1335 ◽

Cited By ~ 3

Author(s):

D. R. Pareddy ◽

R. I. Greyson

Keyword(s):

Amino Acids ◽

Zea Mays ◽

Glutamic Acid ◽

Aspartic Acid ◽

Inbred Line ◽

Casein Hydrolysate ◽

Optimum Concentration ◽

Differential Effects

The effects of amino acids on spikelet development in in vitro cultured tassels of Zea mays inbred line Oh43 were studied. Single amino acids had differential effects on growth and differentiation of cultured tassels. While a few amino acids (arginine, lysine, valine, and proline) were stimulatory, most of the amino acids were either ineffective (serine, leucine, glycine, threonine, methionine, phenylalanine, histidine, aspartic acid, and tyrosine) or inhibitory (isoleucine, asparagine, tryptophan, glutamic acid, and alanine), at a concentration of 30 mg/L, to the development of "normal" spikelets and also to tassel growth. A mixture of the stimulatory amino acids at their optimal concentrations (arginine, 15 mg/L; lysine, 60 mg/L; valine, 120 mg/L; proline, 15 mg/L) produced the maximum number of "normal" spikelets, thereby duplicating the effect of an optimum concentration of casein hydrolysate.

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TRANSFORMATION DE L'ACIDE γ-HYDROXYGLUTAMIQUE EN ALANINE ET EN ACIDE GLYOXYLIQUE

Canadian Journal of Biochemistry and Physiology ◽

10.1139/o61-173 ◽

1961 ◽

Vol 39 (10) ◽

pp. 1595-1603 ◽

Cited By ~ 11

Author(s):

L. P. Bouthillier ◽

Y. Binette ◽

G. Pouliot

Keyword(s):

Amino Acids ◽

Comparative Study ◽

Glutamic Acid ◽

Aspartic Acid ◽

Glyoxylic Acid ◽

Racemic Mixture ◽

Animal Tissues ◽

Direct Formation ◽

Liver Homogenates

A method is described for the synthesis of γ-hydroxyglutamic-5-C14 acid (racemic mixture). Doses of this substance were administered intraperitoneally to rats and among the amino acids isolated from the tissue proteins, glycine showed the highest radioactivity. This finding is compatible with the postulated theory that γ-hydroxyglutamic acid may be cleaved with the formation of alanine and glyoxylic acid, the latter being normally converted into glycine by amination in the animal tissues. Following the incubation of γ-hydroxyglutamic-5-C14 acid and also γ-hydroxyglutamic-2-C14 acid in the presence of rat liver homogenates, evidence was obtained, by the carrier technique, for the direct formation of radioactive glyoxylic acid and alanine; no trace of glutamic acid or aspartic acid could be detected in the incubation media. As a result of a comparative study of the breakdown in vitro of the racemates of γ-hydroxyglutamic-5-C14 acid, it was found that the isomers of erythro-DL-γ-hydroxyglutamic acid are utilized to a much greater extent than the isomers of threo-DL-γ-hydroxyglutamic acid.

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Purification of Synechocystis sp. Strain PCC6308 Cyanophycin Synthetase and Its Characterization with Respect to Substrate and Primer Specificity

Applied and Environmental Microbiology ◽

10.1128/aem.67.5.2176-2182.2001 ◽

2001 ◽

Vol 67 (5) ◽

pp. 2176-2182 ◽

Cited By ~ 37

Author(s):

Elsayed Aboulmagd ◽

Fred B. Oppermann-Sanio ◽

Alexander Steinbüchel

Keyword(s):

Methyl Ester ◽

Glutamic Acid ◽

Aspartic Acid ◽

Gel Filtration ◽

Maximum Activity ◽

Exchange Chromatography ◽

In Vitro Synthesis ◽

Complete Reaction ◽

Cyanophycin Synthetase

ABSTRACT Synechocystis sp. strain PCC6308 cyanophycin synthetase was purified 72-fold in three steps by anion exchange chromatography on Q Sepharose, affinity chromatography on the triazine dye matrix Procion Blue HE-RD Sepharose, and gel filtration on Superdex 200 HR from recombinant cells of Escherichia coli. The native enzyme, which catalyzed the incorporation of arginine and aspartic acid into cyanophycin, has an apparent molecular mass of 240 ± 30 kDa and consists of identical subunits of 85 ± 5 kDa. The K m values for arginine (49 μM), aspartic acid (0.45 mM), and ATP (0.20 mM) indicated that the enzyme had a high affinity towards these substrates. During in vitro cyanophycin synthesis, 1.3 ± 0.1 mol of ATP per mol of incorporated amino acid was converted to ADP. The optima for the enzyme-catalyzed reactions were pH 8.2 and 50°C, respectively. Arginine methyl ester (99.5 and 97% inhibition), argininamide (99 and 96%), S-(2-aminoethyl) cysteine (43 and 42%), β-hydroxy aspartic acid (35 and 37%), aspartic acid β-methyl ester (38 and 40%), norvaline (0 and 3%), citrulline (9 and 7%), and asparagine (2 and 0%) exhibited an almost equal inhibitory effect on the incorporation of both arginine and aspartic acid, respectively, when these compounds were added to the complete reaction mixture. In contrast, the incorporation of arginine was diminished to a greater extent than that of aspartic acid, respectively, with canavanine (82 and 53%), lysine (36 and 19%), agmatine (33 and 25%), d-aspartic acid (37 and 30%), l-glutamic acid (13 and 5%), and ornithine (23 and 11%). On the other hand, canavanine (45% of maximum activity) and lysine (13%) stimulated the incorporation of aspartic acid, whereas aspartic acid β-methyl ester (53%) and asparagine (9%) stimulated the incorporation of arginine. [3H]lysine (15% of maximum activity) and [3H]canavanine (13%) were incorporated into the polymer, when they were either used instead of arginine or added to the complete reaction mixture, whereas l-glutamic acid was not incorporated. No effect on arginine incorporation was obtained by the addition of other amino acids (i.e., alanine, histidine, leucine, proline, tryptophan, and glycine). Various samples of chemically synthesized poly-α,β-d,l-aspartic acid served as primers for in vitro synthesis of cyanophycin, whereas poly-α-l-aspartic acid was almost inactive.

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Features of amino acid metabolism in Moniliformis moniliformis (Acanthocephala) in vitro

Parasitology ◽

10.1017/s0031182000055876 ◽

1987 ◽

Vol 94 (3) ◽

pp. 533-541 ◽

Cited By ~ 1

Author(s):

P. F. V. Ward ◽

D. W. T. Crompton

Keyword(s):

Carbon Dioxide ◽

Amino Acid ◽

Glutamic Acid ◽

Aspartic Acid ◽

Metabolic Pathways ◽

Volatile Compound ◽

Amino Acid Metabolism ◽

Acid Metabolism ◽

Moniliformis Moniliformis

Experiments to investigate the metabolism of glycine, L-glutamic acid and L-aspartic acid by Moniliformis moniliformis were carried out by incubating adult worms aerobically for 3 h at 37°C in Tyrode's solution containing either [U-14C]glycine, L-[U-14C]glutamic acid, L-[U-14C]aspartic acid or L-[4-14C]aspartic acid. Much of the glycine and glutamic acid was absorbed by the worms, but little of either was metabolized. Aspartic acid was readily taken up and metabolized. After incubating with L[U-14C]aspartic acid, most radioactivity was found in ethanol and a volatile compound, presumed to be carbon dioxide, with smaller amounts in lactate, alanine, acetate, malate, glucose and succinate. After incubating with L-[4-14C]aspartic acid, most radioactivity was found in lactate and the presumed CO2 with small amounts in alanine, malate and succinate. No radioactivity was found associated with ethanol or acetate. Possible metabolic pathways and suggestions for a relationship between the metabolism of aspartate with that of alanine and serine in this parasite are discussed.

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THE EFFECT OF HYDROXYLAMINE AND AMINOOXYACETIC ACID ON THE CEREBRAL IN VITRO UTILIZATION OF GLUCOSE, FRUCTOSE, GLUTAMIC ACID, AND γ-AMINOBUTYRIC ACID

Canadian Journal of Biochemistry ◽

10.1139/o65-099 ◽

1965 ◽

Vol 43 (7) ◽

pp. 865-876 ◽

Cited By ~ 18

Author(s):

Bernard Haber

Keyword(s):

Glutamic Acid ◽

Aspartic Acid ◽

Brain Cortex ◽

Pyridoxal Phosphate ◽

Aminobutyric Acid ◽

Aminooxyacetic Acid ◽

Inhibitory Effects ◽

Brain Cortex Slices ◽

Cortex Slices

The aerobic incubation of rat brain cortex slices leads to rapid incorporation of metabolite carbon from both glucose-U-C14 and fructose-U-C14 into glutamic acid, aspartic acid, glutamine, alanine, and γ-aminobutyric acid (γABA). Use of labeled glutamic acid results in a greater incorporation into aspartic acid, and no labeling of alanine. The incorporation from γABA-1-C14 is lowest, and does not result in labeling of alanine. Both hydroxylamine and aminooxyacetic acid (AOAA) abolish the incorporation of metabolite carbon into γABA and alanine, and diminish that of glutamine, with labeling of aspartic acid diminished with fructose as the substrate. Both inhibitors abolish all amino acid labeling from γABA-1-C14, and exert differing effects on incorporation from glutamic acid, depending on the presence or absence of glucose. The respiration of brain cortex slices is markedly diminished by AOAA and by the higher concentration of hydroxylamine, whereas with fructose 0.5 mM hydroxylamine is also effective. Similar inhibitory effects are observed on the C14O2 production. The inhibitory effects of AOAA on incorporation of metabolite carbon from glucose, the respiration, and the carbon dioxide production are reversed by pyridoxal phosphate, and spectrophotometric data indicate that this is due to complex formation between the vitamin and the inhibitor.

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Stereocomplexation Assisted Assembly of Poly(γ-glutamic Acid)-graft-polylactide Nano-micelles and Their Efficacy as Anticancer Drug Carrier

Anti-Cancer Agents in Medicinal Chemistry ◽

10.2174/1871520617666170911170104 ◽

2018 ◽

Vol 18 (2) ◽

pp. 302-311

Author(s):

Shulin Dai ◽

Yucheng Feng ◽

Shuyi Li ◽

Yuxiao Chen ◽

Meiqing Liu ◽

...

Keyword(s):

Glutamic Acid ◽

Drug Carrier ◽

Drug Loading ◽

Drug Carriers ◽

Cancer Drug ◽

Drug Release Profile ◽

Sustained Drug Release ◽

Anti Cancer ◽

Physical Interactions

Background: Micelles as drug carriers are characterized by their inherent instability due to the weak physical interactions that facilitate the self-assembly of amphiphilic block copolymers. As one of the strong physical interactions, the stereocomplexation between the equal molar of enantiomeric polylactides, i.e., the poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), may be harnessed to obtain micelles with enhanced stability and drug loading capacity and consequent sustained release. </P><P> Aims/Methods: In this paper, stereocomplexed micelles gama-PGA-g-PLA micelles) were fabricated from the stereocomplexation between poly(gama-glutamic acid)-graft-PLLA gama-PGA-g-PLA) and poly(gamaglutamic acid)-graft-PDLA gama-PGA-g-PLA). These stereocomplexed micelles exhibited a lower CMC than the corresponding enantiomeric micelles. Result: Furthermore, they showed higher drug loading content and drug loading efficiency in addition to more sustained drug release profile in vitro. In vivo imaging confirmed that the DiR-encapsulated stereocomplexed gama-PGA-g-PLA micelles can deliver anti-cancer drug to tumors with enhanced tissue penetration. Overall, gama-PGA-g-PLA micelles exhibited greater anti-cancer effects as compared with the free drug and the stereocomplexation may be a promising strategy for fabrication of anti-cancer drug carriers with significantly enhanced efficacy.

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