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BMC Plant Biology Mar 2023Neoporphyra haitanensis is a commercial laver species in China. Aspartic acid is an important flavor amino acid, and aspartate aminotransferase (AAT) is a crucial enzyme...
BACKGROUND
Neoporphyra haitanensis is a commercial laver species in China. Aspartic acid is an important flavor amino acid, and aspartate aminotransferase (AAT) is a crucial enzyme in its biosynthesis. In this study, we cloned one AAT gene (NhAAT) from the red alga N. haitanensis and investigated its sequence structure, transcriptional expression and enzymatic characteristics. The purpose of our research is to obtain a functional AAT responsible for the biosynthesis of aspartic acid from red seaweeds, which has the potential to influence the flavor of N. haitanensis.
RESULTS
Sequence analysis showed that NhAAT contains a conserved domain of Aminotran_1_2, which belongs to the transaminase superfamily. The secondary structure of NhAAT is dominated by α-helix. The results of enzymatic characterization illustrated that the NhAAT has highest catalytic activity at 45 °C and pH 7.5 in both forward and reverse reactions. The calculated K values of NhAAT was 5.67 and 6.16 mM for L-glutamic acid and L-aspartic acid, respectively. Quantitative analysis showed that the NhAAT expression of N. haitanensis collected in late harvest (Dec) was 4.5 times that of N. haitanensis collected in early harvest (Oct), while the aspartic acid content of N. haitanensis collected in late harvest (Dec) was 1.2 times that of N. haitanensis collected in early harvest (Oct).
CONCLUSION
The results of enzyme kinetics indicated that NhAAT prefers to catalyze the reaction in the direction of aspartic acid production. Moreover, the trend of NhAAT expression level was consistent with that of aspartic acid content in N. haitanensis in different harvest periods. Our research is helpful to understand the accumulation and regulation of amino acids in N. haitanensis in different habitats and the taste difference of N. haitanensis in different harvest periods.
Topics: Aspartate Aminotransferases; Aspartic Acid; Rhodophyta; Seaweed; Amino Acids
PubMed: 36941626
DOI: 10.1186/s12870-023-04158-2 -
Molecular Systems Biology Jul 2023While cellular metabolism impacts the DNA damage response, a systematic understanding of the metabolic requirements that are crucial for DNA damage repair has yet to be...
While cellular metabolism impacts the DNA damage response, a systematic understanding of the metabolic requirements that are crucial for DNA damage repair has yet to be achieved. Here, we investigate the metabolic enzymes and processes that are essential for the resolution of DNA damage. By integrating functional genomics with chromatin proteomics and metabolomics, we provide a detailed description of the interplay between cellular metabolism and the DNA damage response. Further analysis identified that Peroxiredoxin 1, PRDX1, contributes to the DNA damage repair. During the DNA damage response, PRDX1 translocates to the nucleus where it reduces DNA damage-induced nuclear reactive oxygen species. Moreover, PRDX1 loss lowers aspartate availability, which is required for the DNA damage-induced upregulation of de novo nucleotide synthesis. In the absence of PRDX1, cells accumulate replication stress and DNA damage, leading to proliferation defects that are exacerbated in the presence of etoposide, thus revealing a role for PRDX1 as a DNA damage surveillance factor.
Topics: Aspartic Acid; DNA Damage; Oxidative Stress; Peroxiredoxins; Reactive Oxygen Species; Humans
PubMed: 37259925
DOI: 10.15252/msb.202211267 -
Carbohydrate Research Aug 2016We describe the synthesis and characterization of 6-phosphofructose-aspartic acid, an intermediate in the metabolism of fructose-asparagine by Salmonella. We also report...
We describe the synthesis and characterization of 6-phosphofructose-aspartic acid, an intermediate in the metabolism of fructose-asparagine by Salmonella. We also report improved syntheses of fructose-asparagine itself and of fructose-aspartic acid.
Topics: Asparagine; Aspartic Acid; Fructosephosphates; Molecular Structure
PubMed: 27258673
DOI: 10.1016/j.carres.2016.05.003 -
The Journal of Biological Chemistry Dec 2007The human UDP-glucuronosyltransferase UGT1A6 is the primary phenol-metabolizing UDP-glucuronosyltransferase isoform. It catalyzes the nucleophilic attack of phenolic...
The human UDP-glucuronosyltransferase UGT1A6 is the primary phenol-metabolizing UDP-glucuronosyltransferase isoform. It catalyzes the nucleophilic attack of phenolic xenobiotics on UDP-glucuronic acid, leading to the formation of water-soluble glucuronides. The catalytic mechanism proposed for this reaction is an acid-base mechanism that involves an aspartic/glutamic acid and/or histidine residue. Here, we investigated the role of 14 highly conserved aspartic/glutamic acid residues over the entire sequence of human UGT1A6 by site-directed mutagenesis. We showed that except for aspartic residues Asp-150 and Asp-488, the substitution of carboxylic residues by alanine led to active mutants but with decreased enzyme activity and lower affinity for acceptor and/or donor substrate. Further analysis including mutation of the corresponding residue in other UGT1A isoforms suggests that Asp-150 plays a major catalytic role. In this report we also identified a single active site residue important for glucuronidation of phenols and carboxylic acid substrates by UGT1A enzyme family. Replacing Pro-40 of UGT1A4 by histidine expanded the glucuronidation activity of the enzyme to phenolic and carboxylic compounds, therefore, leading to UGT1A3-type isoform in terms of substrate specificity. Conversely, when His-40 residue of UGT1A3 was replaced with proline, the substrate specificity shifted toward that of UGT1A4 with loss of glucuronidation of phenolic substrates. Furthermore, mutation of His-39 residue of UGT1A1 (His-40 in UGT1A4) to proline led to loss of glucuronidation of phenols but not of estrogens. This study provides a step forward to better understand the glucuronidation mechanism and substrate recognition, which is invaluable for a better prediction of drug metabolism and toxicity in human.
Topics: Aspartic Acid; Catalysis; Glucuronic Acid; Glucuronosyltransferase; Histidine; Humans; Mutagenesis, Site-Directed; Phenols; Substrate Specificity; Xenobiotics
PubMed: 17956868
DOI: 10.1074/jbc.M703107200 -
Progress in Neurobiology Feb 2007The brain is unique among organs in many respects, including its mechanisms of lipid synthesis and energy production. The nervous system-specific metabolite... (Review)
Review
The brain is unique among organs in many respects, including its mechanisms of lipid synthesis and energy production. The nervous system-specific metabolite N-acetylaspartate (NAA), which is synthesized from aspartate and acetyl-coenzyme A in neurons, appears to be a key link in these distinct biochemical features of CNS metabolism. During early postnatal central nervous system (CNS) development, the expression of lipogenic enzymes in oligodendrocytes, including the NAA-degrading enzyme aspartoacylase (ASPA), is increased along with increased NAA production in neurons. NAA is transported from neurons to the cytoplasm of oligodendrocytes, where ASPA cleaves the acetate moiety for use in fatty acid and steroid synthesis. The fatty acids and steroids produced then go on to be used as building blocks for myelin lipid synthesis. Mutations in the gene for ASPA result in the fatal leukodystrophy Canavan disease, for which there is currently no effective treatment. Once postnatal myelination is completed, NAA may continue to be involved in myelin lipid turnover in adults, but it also appears to adopt other roles, including a bioenergetic role in neuronal mitochondria. NAA and ATP metabolism appear to be linked indirectly, whereby acetylation of aspartate may facilitate its removal from neuronal mitochondria, thus favoring conversion of glutamate to alpha ketoglutarate which can enter the tricarboxylic acid cycle for energy production. In its role as a mechanism for enhancing mitochondrial energy production from glutamate, NAA is in a key position to act as a magnetic resonance spectroscopy marker for neuronal health, viability and number. Evidence suggests that NAA is a direct precursor for the enzymatic synthesis of the neuron specific dipeptide N-acetylaspartylglutamate, the most concentrated neuropeptide in the human brain. Other proposed roles for NAA include neuronal osmoregulation and axon-glial signaling. We propose that NAA may also be involved in brain nitrogen balance. Further research will be required to more fully understand the biochemical functions served by NAA in CNS development and activity, and additional functions are likely to be discovered.
Topics: Animals; Aspartic Acid; Canavan Disease; Central Nervous System; Energy Metabolism; Humans; Lipid Metabolism; Metabolic Networks and Pathways
PubMed: 17275978
DOI: 10.1016/j.pneurobio.2006.12.003 -
Analytical Chemistry Sep 2011Formation of isoaspartic acid (isoAsp) is a common modification of aspartic acid (Asp) or asparagine (Asn) residue in proteins. Differentiation of isoAsp and Asp...
Formation of isoaspartic acid (isoAsp) is a common modification of aspartic acid (Asp) or asparagine (Asn) residue in proteins. Differentiation of isoAsp and Asp residues is a challenging task owing to their similar properties and identical molecular mass. It was recently shown that they can be differentiated using ion-electron or ion-ion interaction fragmentation methods (ExD) because these methods provide diagnostic fragments c + 57 and z(•) - 57 specific to the isoAsp residue. To date, however, the presence of such fragments has not been explored on peptides with an N-terminal isoAsp residue. To address this question, several N-terminal isoAsp-containing peptides were analyzed using ExD methods alone or combined with chromatography. A diagnostic fragment [M + 2H - 74](+•) was observed for the doubly charged precursor ions with N-terminal isoAsp residues. For some peptides, identification of the N-terminal isoAsp residue was challenging because of the low diagnostic ion peak intensity and the presence of interfering peaks. Supplemental activation was used to improve diagnostic ion detection. Further, N-terminal acetylation was offered as a means to overcome the interference problem by shifting the diagnostic fragment peak to [M + 2H - 116](+•).
Topics: Amino Acid Sequence; Angiotensin II; Aspartic Acid; Chromatography, High Pressure Liquid; Chromatography, Reverse-Phase; Isoaspartic Acid; Mass Spectrometry; Peptides
PubMed: 21736361
DOI: 10.1021/ac201223d -
Neuroimaging Clinics of North America Aug 2013Neurodegenerative dementias are characterized by elevated myoinositol and decreased N-acetylaspartate (NAA) levels. The increase in myoinositol seems to precede... (Review)
Review
Neurodegenerative dementias are characterized by elevated myoinositol and decreased N-acetylaspartate (NAA) levels. The increase in myoinositol seems to precede decreasing NAA levels in Alzheimer's diseases. NAA/myo-inositol ratio in the posterior cingulate gyri decreases with increasing burden of Alzheimer's disease pathologic conditions. Proton magnetic resonance spectroscopy ((1)H MRS) is sensitive to the pathophysiologic processes associated with the risk of dementia in patients with mild cognitive impairment. Although significant progress has been made in improving the acquisition and analysis techniques in (1)H MRS, translation of these technical developments to clinical practice have not been effective because of the lack of standardization for multisite applications and normative data and an insufficient understanding of the pathologic basis of (1)H MRS metabolite changes.
Topics: Aspartic Acid; Biomarkers; Brain; Dementia; Humans; Inositol; Magnetic Resonance Spectroscopy
PubMed: 23928196
DOI: 10.1016/j.nic.2012.10.004 -
International Journal of Molecular... Aug 2021Poly(aspartamide) derivatives, one kind of amino acid-based polymers with excellent biocompatibility and biodegradability, meet the key requirements for application in... (Review)
Review
Poly(aspartamide) derivatives, one kind of amino acid-based polymers with excellent biocompatibility and biodegradability, meet the key requirements for application in various areas of biomedicine. Poly(aspartamide) derivatives with stimuli-responsiveness can usually respond to external stimuli to change their chemical or physical properties. Using external stimuli such as temperature and pH as switches, these smart poly(aspartamide) derivatives can be used for convenient drug loading and controlled release. Here, we review the synthesis strategies for preparing these stimuli-responsive poly(aspartamide) derivatives and the latest developments in their applications as drug carriers.
Topics: Aspartic Acid; Delayed-Action Preparations; Drug Carriers; Hydrogen-Ion Concentration; Polymers; Temperature
PubMed: 34445521
DOI: 10.3390/ijms22168817 -
Proceedings of the National Academy of... Oct 2018Human genetic studies have given evidence of familial, disease-causing mutations in the analogous amino acid residue shared by three related RNA binding proteins...
Human genetic studies have given evidence of familial, disease-causing mutations in the analogous amino acid residue shared by three related RNA binding proteins causative of three neurological diseases. Alteration of aspartic acid residue 290 of hnRNPA2 to valine is believed to predispose patients to multisystem proteinopathy. Mutation of aspartic acid 262 of hnRNPA1 to either valine or asparagine has been linked to either amyotrophic lateral sclerosis or multisystem proteinopathy. Mutation of aspartic acid 378 of hnRNPDL to either asparagine or histidine has been associated with limb girdle muscular dystrophy. All three of these aspartic acid residues map to evolutionarily conserved regions of low-complexity (LC) sequence that may function in states of either intrinsic disorder or labile self-association. Here, we present a combination of solid-state NMR spectroscopy with segmental isotope labeling and electron microscopy on the LC domain of the hnRNPA2 protein. We show that, for both the wild-type protein and the aspartic acid 290-to-valine mutant, labile polymers are formed in which the LC domain associates into an in-register cross-β conformation. Aspartic acid 290 is shown to be charged at physiological pH and immobilized within the polymer core. Polymers of the aspartic acid 290-to-valine mutant are thermodynamically more stable than wild-type polymers. These observations give evidence that removal of destabilizing electrostatic interactions may be responsible for the increased propensity of the mutated LC domains to self-associate in disease-causing conformations.
Topics: Amino Acid Sequence; Aspartic Acid; Heterogeneous-Nuclear Ribonucleoprotein Group A-B; Humans; Mutagenesis, Site-Directed; Mutation; Nuclear Magnetic Resonance, Biomolecular; Polymers; Protein Conformation; Protein Domains
PubMed: 30279180
DOI: 10.1073/pnas.1806174115 -
Analytical Chemistry Dec 2009Amyloid beta peptides are the major components of the vascular and plaque amyloid filaments in individuals with Alzheimer's disease (AD). Although it is still unclear...
Amyloid beta peptides are the major components of the vascular and plaque amyloid filaments in individuals with Alzheimer's disease (AD). Although it is still unclear what initiates the disease, isomerization of aspartic acid residues in Abeta peptides is directly related to the pathology of AD. The detection of isomerization products is analytically challenging, due to their similar chemical properties and identical molecular mass. Different methods have been applied to differentiate and quantify the isomers, including immunology, chromatography, and mass spectrometry. Typically, those methods require comparative analysis with the standard peptides and involve many sample preparation steps. To understand the role of Abeta isomerization in AD progression, a fast, simple, accurate, and reproducible method is necessary. In this work, electron capture dissociation (ECD) Fourier-transform ion cyclotron resonance mass spectrometry (FTICR MS) was applied to detect isomerization in Abeta peptides. ECD generated diagnostic fragment ions for the two isomers of Abeta17-28, [M + 2H - 60]+* and z6*-44 when aspartic acid was present and z6*-57 when isoaspartic acid was present. Additionally, the z(n)-57 diagnostic ion was also observed in the electron ionization dissociation (EID) spectra of the modified Abeta17-28 fragment. ECD was further applied toward Abeta1-40 and Abeta1-42. The diagnostic ion c6 + 57 was observed in the ECD spectra of the Abeta1-42 peptide, demonstrating isomerization at residue 7. In conclusion, both ECD and EID can clearly determine the presence and the position of isoaspartic acid residues in amyloid beta peptides. The next step, therefore, is to apply this method to analyze samples of Alzheimer's patients and healthy individuals in order to generate a better understanding of the disease.
Topics: Amino Acid Sequence; Amyloid beta-Peptides; Analytic Sample Preparation Methods; Aspartic Acid; Electrons; Fourier Analysis; Hydrophobic and Hydrophilic Interactions; Isoaspartic Acid; Isomerism; Mass Spectrometry; Peptide Fragments; Time Factors
PubMed: 19873993
DOI: 10.1021/ac901677t