A microbiological method for the determination of L- and D-aspartic acids.
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Aspartic Acid↗
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[Effect of glutamic and aspartic acids on heart metabolism and function in hypoperfusion].
The effects of glutamic and aspartic acids were studied during hypoperfusion of the rat isolated heart. The ischemic contracture that develops during hypoperfusion was prevented by glutamic acid. This effect was accompanied by preservation of higher tissue levels of ATP and CP, elimination of glutamate and aspartate deficiency, intensification of ammonia binding through the synthesis of glutamine, asparagine and urea by the myocardium. Nevertheless the level of free ammonia in the tissue remained fairly high. Aspartic acid had a similar but less pronounced effect on heart function and metabolism. The mechanism of contractile function preservation by amino acids appears to be connected with activation of oxidative and substrate phosphorylation in mitochondria rather than with the reduced level of free ammonia.
Adenosine Triphosphate↗
Aspartic acid at position 57 of the HLA-DQ beta chain is not protective against insulin-dependent diabetes mellitus in Japanese people.
Insulin-dependent diabetes mellitus (IDDM) in Caucasians is closely associated with the HLA-DQ gene, especially the residue 57 of the DQ beta chain. Aspartic acid at this position provides protection against IDDM, and substitution of this residue by alanine, valine or serine increases susceptibility to IDDM. To determine whether this is a common feature of IDDM in different ethnic groups, we studied DQB1 DNA in Japanese patients with IDDM by polymerase chain reaction and non-radioactive restriction site analysis. In contrast to Caucasian patients with IDDM, most Japanese patients with IDDM possessed at least one aspartic acid at position 57 of DQ beta. This finding strongly suggests that aspartic acid at position 57 of DQ beta does not protect the Japanese from IDDM.
Amino Acids↗
Functional roles of aspartic acid residues at the cytoplasmic surface of bacteriorhodopsin.
The functions of the four aspartic acid residues in interhelical loops at the cytoplasmic surface of bacteriorhodopsin, Asp-36, Asp-38, Asp-102, and Asp-104, were investigated by studying single and multiple aspartic acid to asparagine mutants. The same mutants were examined also with the additional D96N residue replacement. The kinetics of the M and N intermediates of the photochemical cycles of these recombinant proteins were affected only in a minor, although self-consistent, way. When residue 38 is an aspartate and anionic, it makes the internal proton exchange between the retinal Schiff base and Asp-96 about 3 times more rapid, and events associated with the reisomerization of retinal to all-trans about 3 times slower. Asp-36 has the opposite effect on these processes, but to a smaller extent. Asp-102 and Asp-104 have even less or none of these effects. Of the four aspartates, only Asp-36 could play a direct role in proton uptake at the cytoplasmic surface. In the 13 bacterioopsin sequences now available, only this surface aspartate is conserved.
Amino Acid Sequence↗
Synthesis and characterization of aspartic acid complexes of antimony and bismuth triiodide.
New bioinorganic complexes of the aspartic acid with the antimony or bismuth triiodide were synthesized by a direct solid-solid reaction at room temperature. The formula of the complex is MI(3)[OOCCH(2)CH(NH(2))CO](2.5) x 2.5H(2)O (M = Sb, Bi). The complex may be a dimer with bridge structure. The crystal structure of the complexes belongs to a triclinic system. The lattice parameters are a = 0.9883 nm, b = 1.4284 nm, c = 2.0114 nm, alpha = 94.46 degrees , beta = 99.76 degrees and gamma = 100.1 degrees for the complex of antimony and a = 0.9756 nm, b = 1.4560 nm, c = 1.9875 nm, alpha = 94.18 degrees , beta = 97.25 degrees and gamma = 101.16 degrees for the complex of bismuth. The infrared spectra and thermal analyses can demonstrate the complex formation between the aspartic acid and the antimony or bismuth ion.
Antimony↗
Catalysis of the oligomerization of O-phospho-serine, aspartic acid, or glutamic acid by cationic micelles.
Treatment of relatively concentrated aqueous solutions of O-phospho-serine (50 mM), aspartic acid (100 mM) or glutamic acid (100 mM) with carbonyldiimidazole leads to the formation of an activated intermediate that oligomerizes efficiently. When the concentration of amino acid is reduced tenfold, few long oligomers can be detected. Positively-charged cetyltrimethyl ammonium bromide micelles concentrate the negatively-charged activated intermediates of the amino acids at their surfaces and catalyze efficient oligomerization even from dilute solutions.
Amino Acids↗
Accumulation of D-aspartic acid with age in the human brain.
An age-related accumulation of D-aspartic acid was detected in the white matter of ten normal brains from individuals aged 30 to 80 years. Gray matter showed no systematic increase in D-aspartic acid. The rate constant for D-aspartate formation in the brain is equal to the predicted value calculated for 37 degrees C. Accumulation of the uncommon D-aspartate isomer in myelinated white matter implies that there is little or no turnover of this tissue, and this may have a bearing on dysfunction of the aging brain or on other diseases of myelin.
Adult↗
Aspartic acid nucleates the apatite crystallites of bone: a hypothesis.
This review concentrates on the physical state of bone mineral at the nanosize range, where it exists as ultrathin, tiny, platelike particles. They have a distinct X-ray pattern, different from that of apatite crystals, but shared by all bone matter irrespective of source or architecture. The main feature of this diffractogram is a broadened undifferentiated and asymmetric peak at about 32 degrees. The mineral contains several percents of carbonate and also other foreign elements and ions at low concentrations. When new bone is regenerated at a site of damage or resorption, such nanoparticles have to be created as the first step to progressive organizations at higher levels of bone composition. They are generated under cellular control. As they are produced in huge numbers, homogeneous in character, there is no escape from the conclusion that they are nucleated on compounds excreted by the cells and being not foreign to the surrounding. Evidence has been obtained that aspartic acid (AspA), one of the amino acids, which compose all life, has a specific beneficial effect on bone regeneration in an animal model experiment. An analysis of the possible interaction between aspartic acid molecule and the crystallographic unit cell of hydroxyapatite was attempted and is presented in this review. Hydroxyapatite has a large and complex unit cell, and therefore the interaction between such unit and a tiny acid calls for a special array in which the aspartic acid is enclosed inside a carbonated, calcium deficient unit, apparently without changing its external appearance and is able to start assemblage of regular apatite units. The nucleation event depends upon substitution of four carbonate ions in the sites of four phosphate ions. This substitution causes generation of four voids that can accommodate the four terminal oxygen of the aspartic acid. Such unit serves as a nucleating unit.
Animals↗
Characterization of a protein containing D-aspartic acid in aged mouse lens.
A protein containing D-aspartic acid (D-Asp) was isolated from water insoluble (WI) fraction of naturally aged mice lens. The molecular weight of this protein was estimated to be about 10000 by gel permeation chromatography. High content of serine and glycine was noteworthy and the two amino acids occupy about 50 % of the total amino acids in the protein containing D-Asp.
Aging↗
A minimal transcription activation domain consisting of a specific array of aspartic acid and leucine residues.
Transcriptional activation by the herpesvirus protein VP16 (= Vmw65, alpha TIF) is mediated by its C-terminal acidic activation domain. Using GAL4 fusion proteins, we have previously shown that a construct containing two tandem copies of a short eleven amino acid fragment derived from the VP16 domain (DALDDFDLDML, residues 437-447) activates transcription in mammalian cells with an efficiency comparable to a GAL4 fusion with the full VP16 activation domain (residues 413-490). Here we have mutagenized this eleven amino acid core sequence and find that a mutant sequence with little inherent activity can cooperate with a wildtype sequence to yield almost full activity. Moreover, greater activity is observed when the wildtype sequence is positioned at the distal, rather than the proximal, end of the fusion protein, indicating that the distal position facilitates contacts to the transcription apparatus. We have also further reduced the eleven amino acid activating sequence to shorter sequence motifs. Two copies of eight and seven amino acids (DALDDFDL and DDFDLDL, respectively), or four copies of the sequence motif DDFDL are required to reach the activation potential of two eleven amino acid motifs. Four copies of the sequence DDLDL still activate transcription strongly (up to two-thirds of DDFDL), indicating that an aromatic residue is not an essential feature of this type of activation domain. However, repetitions of DDL or DL do not yield activity. Thus the minimal requirement for transcriptional activation is the presence of a sequence of some fifteen to twenty amino acids consisting of a specific array of aspartic acid and leucine residues.(ABSTRACT TRUNCATED AT 250 WORDS)
Amino Acid Sequence↗
Synthesis and biodegradation of polymers derived from aspartic acid.
The synthesis of copolymers derived from aspartic acid hydrochloride, their characterization and their hydrolytic degradation and biodegradation by Aspergillus niger and E. coli have been described. The alpha-amino dicarboxylic acid has been copolymerized with 1,2-ethane diol, 1,3-butane diol, 1,4-butane diol, 1,6-hexane diol and glycerol to get copolyesters I, II, III, IV and V respectively. The polymer samples have been characterized by their number average molecular weight (Mn), elemental analysis and their i.r. spectra. The copolyester V is crosslinked. All of the copolyesters I-V undergo slow hydrolytic degradation in aqueous solution at ambient temperatures as studied by the measurement of the decrease in reduced viscosity and increase in specific conductance of their aqueous solutions. They are also degraded in aqueous suspension by the fungus Aspergillus niger and by the bacterium E. coli. Degradation by Aspergillus niger mainly depends on the polarity of the polymers, the more polar polymers being less degradable. On the other hand, degradation by E. coli is primarily dependent upon the alpha-NH2 group contents of the polymers, the alpha-NH2 group rich polymers being more degradable. The possible use of these polymers as biodegradable drug carriers has been suggested.
Aspartic Acid↗
Aggrecan turnover in human intervertebral disc as determined by the racemization of aspartic acid.
We have used the racemization of aspartic acid as a marker for the "molecular age" of aggrecan components of the human intervertebral disc matrix (aggregating and non-aggregating proteoglycans as well as the different buoyant density fractions of aggrecan). By measuring the D/L(Asp) ratio of the various aggrecan species as a function of age and using the values of the racemization constant, k(i), found earlier for aggrecan in articular cartilage, we were able to establish directly the relative residence time of these molecules in human intervertebral disc matrix. For A1 preparations taken from normal tissue, turnover rates of 0.059 +/- 0.01 and 0.063 +/- 0.01/year correspond to half-life values of 12 +/- 2.0 and 11.23 +/- 1.9 years for nucleus pulposus and annulus fibrosus, respectively; the turnover rates of 0.084 +/- 0.022 and 0.092 +/- 0.034/year for degenerate tissue correspond to half-life values of 8.77 +/- 2.2 and 8.41 +/- 2.8 years, suggesting increased rate of removal of small aggrecan fragments. For the large monomer, fraction A1D1, turnover is 0.13 +/- 0.04/year, corresponding to a half-life of 5.56 +/- 1.58 years, similar to 3.4 years in human articular cartilage. For the binding region (A1D6), turnover is 0.033 +/- 0.0012/year, corresponding to a half-life of 21.53 +/- 0.6 years, similar to 23.5 years in articular cartilage. A1 preparations from nucleus pulposus contain a lower proportion of aggregating proteoglycans as compared with annulus fibrosus, suggesting increased proteolytic modification in the nucleus pulposus. D/L(Asp) values in aggregating and non-aggregating proteoglycans of a 24-year-old individual show similar results, suggesting that the non-aggregating molecules are synthesized initially as aggregating proteoglycans, which thereafter undergo cleavage and detachment from hyaluronan.
Adolescent↗
[The effect of early visual deprivation on the synthesis of glutamic and aspartic acids in mitochondria of central structures of the visual analyzer in the dog].
After 45 days visual deprivation synthesis via direct reductive amination and transamination of glutamic and aspartic acids was inhibited in mitochondria of dog visual cortex, colliculi anterioris and corpus geniculatum externus. Under conditions of long-term (90 days) visual deprivation synthesis of glutamic and aspartic acids was less effectively inhibited in mitochondria of the brain areas studied via the reductive amination and transamination, except of the aspartic acid synthesis by means of transamination, the rate of which was maintained at the level similar to the values observed after 45 days of visual deprivation.
Amination↗
Replacement of lysine-181 by aspartic acid in the third transmembrane region of endothelin type B receptor reduces its affinity to endothelin peptides and sarafotoxin 6c without affecting G protein coupling.
A conserved aspartic acid residue in the third transmembrane region of many of the G protein-coupled receptors has been shown to play a role in ligand binding. In the case of endothelin receptors, however, a lysine residue replaces this conserved aspartic acid residue. To access the importance of this residue in ligand binding, we have replaced it with an aspartic acid in the rat endothelin type B (ETb) receptor by PCR mediated mutagenesis. The binding characteristics and functional properties of both the wild type and mutant receptors were determined in COS-7 cells transiently expressing the cloned receptor cDNAs. Using 125I-ET-1 as the radioactive peptide ligand in displacement binding studies, the wild type receptor displayed a typical non-isopeptide-selective binding profile with similar IC50 values (0.2-0.6 nM) for all three endothelin peptides (ET-1, ET-2, and ET-3) and sarafotoxin 6c (SRTX 6c). Interestingly, the mutant receptor showed an increase in IC50 values for ET-1 (5 nM), ET-2 (27 nM), and ET-3 (127 nM) but displayed a much larger increase in IC50 value for SRTX 6c (> 10 uM). The lysine mutant receptor still elicited full inositol phosphate (IP) turnover responses in the presence of saturating concentrations of endothelins (10 nM of ET-1, 100 nM of ET-2, or 1 uM of ET-3), indicating that the mutation (K181D) did not affect the coupling of mutant receptor to the appropriate G protein. These results demonstrate that lysine-181 on the receptor is important for binding ET peptides; however, it is required for binding the ETb selective agonist-SRTX 6c.
Animals↗
CLINICAL AND EXPERIMENTAL STUDIES ON ALPHA-KETO ACIDS METABOLISM. 3. FLUCTUATION OF THE EXCRETION OF ALPHA-KETO ACIDS IN THE URINE OF PANTOTHENIC ACID DEFICIENT RATS TO WHICH FRUCTOSE SODIUM GLUTAMATE AND ASPARTIC ACID ARE ADMINISTERED.
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Aspartic Acid↗
Effects of L-aspartic acid, L-asparagine and/or L-asparaginase on forced swimming-induced immobility, analgesia, and decrease in rectal temperature in rats.
The effect of L-aspartic acid, L-asparagine and/or L-asparaginase were compared with those of imipramine on immobility, number of defecations, increase of nociceptive threshold, and hypothermia, induced by forced swimming in rats. L-Aspartic acid was found to be as effective as imipramine in reducing the effects of forced swimming, presumable by normalizing the decreased level of endogenous L-aspartic acid, due to the inhibition of L-asparaginase activity and/or by stimulating the inhibited enzyme. The other treatments antagonized the immobility, but not the increased number of defecations. All compounds abolished the elevation of nociceptive threshold and hypothermia.
Analgesia↗
Characterization and possible opioid modulation of N-methyl-D-aspartic acid induced increases in serum luteinizing hormone levels in the developing male rat.
It has been previously reported that the excitatory amino acid, N-methyl-D-aspartic acid (NMDA), elicits prompt increases in serum luteinizing hormone (LH) levels in young male rats. The present studies were carried out to determine whether the effects of NMDA on LH were mediated by the release of LHRH from the hypothalamus. We also examined whether NMDA-sensitive neuronal pathways interacted with the endogenous opioid system regulating LHRH release and the ontogeny of NMDA-evoked increases in serum LH. We found that the age-response curve for NMDA-induced increases in LH was an inverted U; at early ages (10 and 15 days) the amino acid was marginally effective in increasing LH levels, it became maximally effective from post-natal days 20-40 and thereafter rapidly lost its efficacy such that it was virtually inactive in adult animals. Dose-response curves revealed that adult animals were more than 10-fold less sensitive to NMDA than their younger counterparts. Our studies also demonstrated that NMDA increased LH via a direct effect on the hypothalamic release of LHRH since a potent LHRH antagonist competitively inhibited the effects of NMDA. Finally, we observed that morphine competitively inhibited the effects of NMDA on LH release, suggesting a relationship between NMDA-sensitive neuronal pathways and those endogenous opioid-containing systems which are known to regulate LH release.
Aging↗
[Role of aspartic acid at position 57 of the HLA-DQ beta chain in sporadic and familial forms of selective IgA deficiency].
BACKGROUND: Selective IgA deficiency (IgAD) is the most frequent primary immunodeficiency in Caucasians. A protective effect of an aspartic acid residue at position 57 of the DQ beta chain against IgAD has been repeatedly described. The aim of our study was to determine, whether the genetic effect of non-aspartic acids (non-Asp) at position 57 of the DQ beta chain is different in familial and non-familial forms of IgAD. METHODS AND RESULTS: Codon 57 genotyping was performed in 59 patients with sporadic from in 28 patients with familial forms of IgAD, and in 162 control persons. Significantly increased occurrence of the non-Asp residues at position 57 in IgAD patients compared to control persons was found, but there was no difference between familial and sporadic forms of IgAD. The association was not proved in six IgAD patients who were relatives of CVID patients. CONCLUSION: The protective effect of non-aspartic acid at position 57 of the DQ beta chain is present in both sporadic and familial form of IgAD. This effect was not observed in IgAD relatives of CVID persons showing that a genetic background of this form might be different than in other forms of IgAD.
Amino Acid Sequence↗