scholarly journals Distribution of Free D-Amino Acids in Bivalve Mollusks and the Effects of Physiological Conditions on the Levels of D- and L-Alanine in the Tissues of the Hard Clam, Meretrix lusoria

1998 ◽  
Vol 64 (4) ◽  
pp. 606-611 ◽  
Author(s):  
Emiko Okuma ◽  
Katsuko Watanabe ◽  
Hiroki Abe
Keyword(s):  
Amino Acids ◽  
Hard Clam ◽  
Bivalve Mollusks ◽  
Physiological Conditions ◽  
Meretrix Lusoria

scholarly journals Dynamic Regulation of Ions and Amino Acids in Adult Asian Hard Clams Meretrix lusoria Upon Hyperosmotic Salinity

2021 ◽  
Vol 8 ◽  
Author(s):  
Chia-Hao Lin ◽  
Po-Ling Yeh ◽  
Yu-Chun Wang ◽  
Tsung-Han Lee
Keyword(s):  
Amino Acids ◽  
Natural Habitat ◽  
Hard Clam ◽  
Salinity Acclimation ◽  
Dynamic Regulation ◽  
Peripheral Tissues ◽  
Key Enzyme ◽  
Mrna And Protein Expression ◽  
Meretrix Lusoria ◽  
Hard Clams

The dynamic regulation of ions and amino acids in the gills and mantle of the Asian hard clam, Meretrix lusoria, following the exposure to a hyperosmotic environment was hitherto unclear. The present study revealed that the osmolality as well as the Na+ and Cl– concentrations in the hemolymph were significantly increased 3 h after transferring the clams from an environment with the salinity of their natural habitat (brackish water; BW; 20‰) to one with hyperosmotic salinity (seawater; 35‰). In addition, we found that the specific activities of Na+/K+-ATPase, a key enzyme that plays a significant role in cell osmoregulation, in the gills and mantle of clams were significantly increased at 72 and 12 h post-transfer, respectively, during acclimation to hyperosmotic salinity. Similarly, the contents of free amino acids (FAAs) such as taurine, alanine, and glycine were significantly elevated during hyperosmotic salinity acclimation. Previous research indicates that taurine is the most abundant FAA in the gills and mantles of Asian hard clams and that the taurine transporter (TAUT) plays an important role in taurine accumulation. The present study showed that TAUT mRNA and protein expression were significantly and transiently increased in the mantle of Asian hard clams following exposure to seawater; although the expression of TAUT mRNA in the gills of Asian hard clams was also transiently stimulated by exposure to hyperosmotic salinity, the relative TAUT protein abundance decreased only at later stages. Accordingly, the findings of this study improve our understanding of the dynamic processes of ion and amino acid regulation in the peripheral tissues of bivalves under hyperosmotic stress.

scholarly journals Selective Recognition of Amino Acids and Peptides by Small Supramolecular Receptors

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 106
Author(s):  
Joana N. Martins ◽  
João Carlos Lima ◽  
Nuno Basílio
Keyword(s):  
Amino Acids ◽  
Selective Recognition ◽  
Great Promise ◽  
Macrocyclic Compounds ◽  
Synthetic Receptors ◽  
Small Peptides ◽  
Molecular Imprinted Polymers ◽  
Polymeric Systems ◽  
Physiological Conditions ◽  
Level Information

To this day, the recognition and high affinity binding of biomolecules in water by synthetic receptors remains challenging, while the necessity for systems for their sensing, transport and modulation persists. This problematic is prevalent for the recognition of peptides, which not only have key roles in many biochemical pathways, as well as having pharmacological and biotechnological applications, but also frequently serve as models for the study of proteins. Taking inspiration in nature and on the interactions that occur between several receptors and peptide sequences, many researchers have developed and applied a variety of different synthetic receptors, as is the case of macrocyclic compounds, molecular imprinted polymers, organometallic cages, among others, to bind amino acids, small peptides and proteins. In this critical review, we present and discuss selected examples of synthetic receptors for amino acids and peptides, with a greater focus on supramolecular receptors, which show great promise for the selective recognition of these biomolecules in physiological conditions. We decided to focus preferentially on small synthetic receptors (leaving out of this review high molecular weight polymeric systems) for which more detailed and accurate molecular level information regarding the main structural and thermodynamic features of the receptor biomolecule assemblies is available.

Carboxyalkylchitosan-based hydrogels with “imine clip”: enhanced stability and amino acids-induced disassembly under physiological conditions

2021 ◽  
pp. 118618
Author(s):  
Svetlana Bratskaya ◽  
Yuliya Privar ◽  
Anna Skatova ◽  
Arseny Slobodyuk ◽  
Ekaterina Kantemirova ◽  
...  
Keyword(s):  
Amino Acids ◽  
Physiological Conditions ◽  
Enhanced Stability

scholarly journals The conjugation of nonsteroidal anti-inflammatory drugs (NSAID) to small peptides for generating multifunctional supramolecular nanofibers/hydrogels

2013 ◽  
Vol 9 ◽  
pp. 908-917 ◽  
Author(s):  
Jiayang Li ◽  
Yi Kuang ◽  
Junfeng Shi ◽  
Yuan Gao ◽  
Jie Zhou ◽  
...  
Keyword(s):  
Amino Acids ◽  
Critical Concentration ◽  
Therapeutic Agents ◽  
Multiple Roles ◽  
Small Peptides ◽  
Covalent Linkage ◽  
Physiological Conditions ◽  
Racemic Ibuprofen ◽  
Inflammatory Drugs ◽  
Anti Inflammatory

Here we report supramolecular hydrogelators made of nonsteroidal anti-inflammatory drugs (NSAID) and small peptides. The covalent linkage of Phe–Phe and NSAIDs results in conjugates that self-assemble in water to form molecular nanofibers as the matrices of hydrogels. When the NSAID is naproxen (1), the resultant hydrogelator 1a forms a hydrogel at a critical concentration (cgc) of 0.2 wt % at pH 7.0. Hydrogelator 1a, also acting as a general motif, enables enzymatic hydrogelation in which the precursor turns into a hydrogelator upon hydrolysis catalyzed by a phosphatase at physiological conditions. The conjugates of Phe–Phe with other NSAIDs, such as (R)-flurbiprofen (2), racemic flurbiprofen (3), and racemic ibuprofen (4), are able to form molecular hydrogels, except in the case of aspirin (5). After the conjugation with the small peptides, NSAIDs exhibit improved selectivity to their targets. In addition, the peptides made of D-amino acids help preserve the activities of NSAIDs. Besides demonstrating that common NSAIDs are excellent candidates to promote aromatic–aromatic interaction in water to form hydrogels, this work contributes to the development of functional molecules that have dual or multiple roles and ultimately may lead to new molecular hydrogels of therapeutic agents for topical use.

Production and utilization of amino acids by ovine placenta in vivo

1998 ◽  
Vol 274 (1) ◽  
pp. E13-E22 ◽  
Author(s):  
Misoo Chung ◽  
Cecilia Teng ◽  
Michelle Timmerman ◽  
Giacomo Meschia ◽  
Frederick C. Battaglia
Keyword(s):  
Amino Acids ◽  
Branched Chain Amino Acids ◽  
Plasma Amino Acids ◽  
Physiological Conditions ◽  
Ovine Placenta ◽  
Branched Chain ◽  
Glutamine Production

Uterine and umbilical uptakes of plasma amino acids were measured simultaneously in eighteen singleton pregnant ewes at 130 ± 1 days gestation for the purpose of establishing which amino acids are produced or used by the uteroplacenta under normal physiological conditions and at what rates. The branched-chain amino acids (BCAA) had uterine uptakes significantly greater than umbilical uptakes. Net uteroplacental BCAA utilization was 8.0 ± 2.5 μmol ⋅ kg fetus−1 ⋅ min−1( P < 0.005) and represented 42% of the total BCAA utilization by fetus plus uteroplacenta. There was placental uptake of fetal glutamate (4.2 ± 0.3 μmol ⋅ kg fetus−1 ⋅ min−1, P < 0.001) and no uterine uptake of maternal glutamate. Umbilical uptake of glutamine was ∼61% greater than uterine uptake, thus demonstrating net uteroplacental glutamine production of 2.2 ± 0.9 μmol ⋅ kg fetus−1 ⋅ min−1( P < 0.021). In conjunction with other evidence, these data indicate rapid placental metabolism of glutamate, which is in part supplied by the fetus and in part produced locally via BCAA transamination. Most of the glutamate is oxidized, and some is used to synthesize glutamine, which is delivered to the fetus. There was net uteroplacental utilization of maternal serine and umbilical uptake of glycine produced by the placenta. Maternal serine utilization and glycine umbilical uptake were virtually equal (3.14 ± 0.50 vs. 3.10 ± 0.46 μmol ⋅ kg fetus−1 ⋅ min−1). This evidence supports the conclusion that the ovine placenta converts large quantities of maternal serine into fetal glycine.

Sulfation by human lung fibroblasts: SO4(2-) and sulfur-containing amino acids as sources for macromolecular sulfation

1991 ◽  
Vol 260 (6) ◽  
pp. L450-L456 ◽  
Author(s):  
A. Elgavish ◽  
E. Meezan
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Human Lung ◽  
Lung Fibroblasts ◽  
Human Lung Fibroblasts ◽  
Physiological Conditions ◽  
Limiting Step ◽  
Sulfate Incorporation ◽  
Sulfur Containing ◽  
Inorganic Sulfate

Studies were carried out in human lung fibroblasts (IMR-90) to investigate 1) the relative contribution of two extracellular pools, inorganic sulfate and sulfur-containing amino acids, to the intracellular fraction precipitable by trichloroacetic acid and 2) the possibility that the transport of these sulfur-containing substrates at the plasma membrane may be a limiting step for macromolecular sulfation. Our studies indicate that the ability to use SO4(2-) released by intracellular catabolism of the sulfur-containing amino acid L-cysteine differs from one cell system to another. In contrast to smooth muscle cells, in the human lung fibroblast, L-cysteine contributes significantly to the intercellular pool of SO4(2-) used for sulfation at extracellular [SO4(2-)] less than 100 microM. However, under physiological conditions with respect to SO4(2-) ([SO4(2-)]0 = 300 microM), L-cysteine does not contribute greater than 30% of the sulfate incorporated into the cellular fraction. Taurine (2-aminoethanesulfonic acid) inhibits SO4(2-) incorporation into the cell-associated macromolecular fraction. However, results suggest that the effect is not due to either SO4(2-) released by its catabolism or to an effect on SO4(2-) transport into the cell. The fact that the transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid inhibits sulfate incorporation indicates that carrier-mediated sulfate transport at the cellular plasma membrane may be a limiting step for sulfate incorporation. In conclusion, under physiological conditions with respect to SO4(2-), inorganic sulfate is a major source of sulfate for sulfation in human lung fibroblasts and macromolecular sulfation may be limited by its transport into the cells.

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