N-acetylglutamate Research Articles

Accumulation, metabolites formation and elimination behavior of rac-glufosinate-ammonium and glufosinate-P in zebrafish (Danio rerio).

An efficient trace detection method for the determination of residues of the glufosinate enantiomers and metabolites in zebrafish by HPLC-Q-Exactive Orbitrap Mass Spectrometry was developed. After the purification of dichloromethane and Oasis PRiME HLB SPE column, the recovery ranges from 77% to 104%, with RSD<10.03%. The limits of quantitation in zebrafish were 0.006-0.02mg/kg. The results revealed zebrafish absorbed glufosinate slowly, reaching a steady state in 10-14days, and the bioaccumulation factor (BCF) of D/L-glufosinate-ammonium was less than 0.3. L-glufosinate-ammonium accumulated preferentially in zebrafish. The residue of the metabolite N-acetyl glutamate (NAG) was smaller than that of 3-methyl phosphonic acid (MPP). D/L-glufosinate-ammonium had an elimination half-life of less than 2.3days during the elimination phase. The bioaccumulation and elimination behavior of glufosinate-ammonium in zebrafish aquatic system was shown in this work, which offered scientific data for assessing the food safety of rac-glufosinate-ammonium and glufosinate-P (pure L-glufosinate-ammonium) in fish.

Cerebellar Abnormalities on Proton MR Spectroscopy and Imaging in Patients With Gluten Ataxia: A Pilot Study

Gluten ataxia is a rare immune-mediated neurological disorder caused by the ingestion of gluten. The diagnosis is not straightforward as antibodies are present in only up to 38% of patients, but often at lower titers. The symptoms of ataxia may be mild at the onset but lead to permanent damage if remain untreated. It is characterized by damage to the cerebellum however, the pathophysiology of the disease is not clearly understood. The present study investigated the neurochemical profile of vermis and right cerebellum and structural changes in various brain regions of patients with gluten ataxia (n = 6, age range 40–65 years) and compared it with healthy controls (n = 10, 40–55 years). Volumetric 3-D T1 and T1-weighted magnetic resonance imaging (MRI) in the three planes (axial, coronal, and sagittal) of the whole brain and single-voxel 1H- magnetic resonance spectroscopy (MRS) of the vermis and right cerebellum were acquired on 3 T human MR scanner. The metabolite concentrations were estimated using LC Model (6.1–4A) while brain volumes were estimated using the online tool volBrain pipeline and CERES and corrected for partial volumes. The levels of neuro-metabolites (N-acetyl aspartate + N-acetyl aspartate glutamate, glycerophosphocholine + phosphocholine, and total creatine) were found to be significantly lower in vermis, while N-acetyl aspartate + N-acetyl aspartate glutamate and glycerophosphocholine + phosphocholine was lower in cerebellum regions in the patients with gluten ataxia compared to healthy controls. A significant reduction in the white matter of (total brain, cerebellum, and cerebrum); reduction in the volumes of cerebellum lobe (X) and thalamus while lateral ventricles were increased in the patients with gluten ataxia compared to healthy controls. The reduced neuronal metabolites along with structural changes in the brain suggested neuronal degeneration in the patients with gluten ataxia. Our preliminary findings may be useful in understanding the gluten-induced cerebral damage and indicated that MRI and MRS may serve as a non-invasive useful tool in the early diagnosis, thereby enabling better management of these patients.

Influence of endogenous estrogen on a network model of female brain integrity.

Recent reports document sex differences in midlife brain integrity and metabolic health, such that more relationships are detectable between metabolic syndrome (MetS) components and markers of brain health in females than in males. Midlife is characterized by a rapid decrease in endogenous estrogen levels for women which is thought to increase risk for cardiometabolic disease and neurocognitive decline. Our study used network models, designed to explore the interconnectedness and organization of relationships among many variables at once, to compare the influence of endogenous estrogen and chronological age on a network of brain and metabolic health in order to investigate the utility of estrogen as a biomarker for brain vulnerability. Data were analyzed from 82 females (ages 40-62). Networks consisted of known biomarkers of risk for late-life cognitive decline: the five components of MetS; Brain-predicted age difference calculated on gray and white matter volume; white matter hyperintensities; Default Mode Network functional connectivity; cerebral concentrations of N-acetyl aspartate, glutamate and myo-inositol; and serum concentrations of estradiol. A second network replaced estradiol with chronological age. Expected influence (EI) of estradiol on the network was -1.190, relative to chronological age at -0.524, indicating that estradiol had a stronger expected influence over the network than age. A negative expected influence indicates that higher levels of estradiol would be expected to decrease the number of relationships in the model, which is thought to indicate lower risk. Overall, levels of estradiol appear more influential than chronological age at midlife for relationships between brain integrity and metabolic health.

Magnetic resonance spectroscopic evidence of increased choline in the dorsolateral prefrontal and visual cortices in recent onset schizophrenia

A complete characterization of neurometabolite profiles in the dorsolateral prefrontal cortex (DLPFC) in recent onset schizophrenia (SZ) remains elusive. Filling in this knowledge gap is essential in order to better understand how the neurochemistry of this region contributes to SZ pathology. To that end, DLPFC N-acetyl aspartate (NAA), myo-inositol, glutamate, choline, and creatine levels were examined by 3 T magnetic resonance spectroscopy (MRS) in recent onset individuals with SZ (n = 40) and healthy controls (HC) (n = 47). Metabolite levels were also examined in the visual cortex (VC) as a control region. People with SZ showed significantly higher choline in both the DLPFC and VC, but no differences in NAA, myo-inositol, glutamate, or creatine in either region. A trend-level negative correlation was also observed between DLPFC NAA and negative symptoms in SZ. Our results suggest that choline is increased in both the prefrontal and occipital cortices in recent onset SZ, and that DLPFC NAA levels may be inversely related to negative symptoms in the illness. The observed increase in choline-containing compounds in both DLPFC and VC in recent onset SZ could reflect increased membrane remodeling such as occurs in activated microglia and astrocytes in response to neuroinflammation.

Glutamate Carboxypeptidase II in Aging Rat Prefrontal Cortex Impairs Working Memory Performance.

Glutamate carboxypeptidase II (GCPII) expression in brain is increased by inflammation, and reduces NAAG (N-acetyl aspartyl glutamate) stimulation of mGluR3 signaling. Genetic insults in this signaling cascade are increasingly linked to cognitive disorders in humans, where increased GCPII and or decreased NAAG-mGluR3 are associated with impaired prefrontal cortical (PFC) activation and cognitive impairment. As aging is associated with increased inflammation and PFC cognitive deficits, the current study examined GCPII and mGluR3 expression in the aging rat medial PFC, and tested whether GCPII inhibition with 2-(3-mercaptopropyl) pentanedioic acid (2-MPPA) would improve working memory performance. We found that GCPII protein was expressed on astrocytes and some microglia as expected from previous studies, but was also prominently expressed on neurons, and showed increased levels with advancing age. Systemic administration of the GCPII inhibitor, 2-MPPA, improved working memory performance in young and aged rats, and also improved performance after local infusion into the medial PFC. As GCPII inhibitors are well-tolerated, they may provide an important new direction for treatment of cognitive disorders associated with aging and/or inflammation.

Identification of diphenyl furan derivatives via high throughput and computational studies as ArgA inhibitors of Mycobacterium tuberculosis

Microbial amino acid biosynthetic pathways are underexploited for the development of anti-bacterial agents. N-acetyl glutamate synthase (ArgA) catalyses the first committed step in L-arginine biosynthesis and is essential for M. tuberculosis growth. Here, we have purified and optimized assay conditions for the acetylation of l-glutamine by ArgA. Using the optimized conditions, high throughput screening was performed to identify ArgA inhibitors. We identified 2,5-Bis (2-chloro-4-guanidinophenyl) furan, a dicationic diaryl furan derivatives, as ArgA inhibitor, with a MIC99 values of 1.56 μM against M. tuberculosis. The diaryl furan derivative displayed bactericidal killing against both M. bovis BCG and M. tuberculosis. Inhibition of ArgA by the lead compound resulted in transcriptional reprogramming and accumulation of reactive oxygen species. The lead compound and its derivatives showed micromolar binding with ArgA as observed in surface plasmon resonance and tryptophan quenching experiments. Computational and dynamic analysis revealed that these scaffolds share similar binding site residues with L-arginine, however, with slight variations in their interaction pattern. Partial restoration of growth upon supplementation of liquid cultures with either L-arginine or N-acetyl cysteine suggests a multi-target killing mechanism for the lead compound. Taken together, we have identified small molecule inhibitors against ArgA enzyme from M. tuberculosis.

Proton magnetic resonance spectroscopy in frontotemporal lobar degeneration-related syndromes

There is an urgent need for a better understanding of the pathophysiology of cognitive impairment in syndromes associated with frontotemporal lobar degeneration. Here, we used magnetic resonance spectroscopy to quantify metabolite deficits in sixty patients with a clinical syndrome associated with frontotemporal lobar degeneration (behavioral variant frontotemporal dementia n = 11, progressive supranuclear palsy n = 26, corticobasal syndrome n = 11, primary progressive aphasias n = 12), and 38 age- and sex-matched healthy controls. We measured nine metabolites in the right inferior frontal gyrus, superior temporal gyrus and right primary visual cortex. Metabolite concentrations were corrected for age, sex, and partial volume then compared with cognitive and behavioral measures using canonical correlation analysis. Metabolite concentrations varied significantly by brain region and diagnosis (region x metabolite x diagnosis interaction F(64) = 1.73, p < 0.001, corrected for age, sex, and atrophy within the voxel). N-acetyl aspartate and glutamate concentrations were reduced in the right prefrontal cortex in behavioral variant frontotemporal dementia and progressive supranuclear palsy, even after partial volume correction. The reduction of these metabolites was associated with executive dysfunction and behavioral impairment (canonical correlation analysis R = 0.85, p < 0.001).

1H-MRS reveals metabolic alterations in generalized tonic-clonic seizures before and after treatment.

To explore the possible metabolic alterations of bilateral dorsolateral prefrontal cortices (DLPFC) of generalized tonic-clonic seizures (GTCS) patients before and after antiepileptic drugs treatment as compared with healthy controls (HCs) using proton magnetic resonance spectroscopy (1H-MRS). We included 23 newly diagnosed and unmedicated GTCS patients and 23sex- and age-matched HCs. Metabolites including N-acetyl aspartate (NAA), myo-inositol (Ins), choline (Cho), creatine (Cr), and glutamate+glutamine (Glu+Gln, Glx) concentrations were quantified by using LCModel software and then corrected for the partial volume effect of cerebrospinal fluid. The results demonstrated that metabolite concentrations were not equal between the left and the right DLPFC. Compared with HC, NAA of the left DLPFC and Cr of the right DLPFC were significantly lower in pre-treatment patients. Self-controlled study revealed that the patients' NAA of the left DLPFC increased while their Cr of the right DLPFC decreased after treatment. Correlation analysis showed a negative correlation between the duration of medication and the pre- and post-treatment difference of Cr. These findings may shed a light on the metabolic mechanism of GTCS and the neurobiochemical mechanisms of AEDs.

Noncoding sequence variants define a novel regulatory element in the first intron of the N-acetylglutamate synthase gene.

N-acetylglutamate synthase deficiency is an autosomal recessive urea cycle disorder caused either by decreased expression of the NAGS gene or defective NAGS enzyme resulting in decreased production of N-acetylglutamate (NAG), an allosteric activator of carbamylphosphate synthetase 1 (CPS1). NAGSD is the only urea cycle disorder that can be effectively treated with a single drug, N-carbamylglutamate (NCG), a stable NAG analog, which activates CPS1 to restore ureagenesis. We describe three patients with NAGSD due to four novel noncoding sequence variants in the NAGS regulatory regions. All three patients had hyperammonemia that resolved upon treatment with NCG. Sequence variants NM_153006.2:c.427-222G>A and NM_153006.2:c.427-218A>C reside in the 547 bp-long first intron of NAGS and define a novel NAGS regulatory element that binds retinoic X receptor α. Sequence variants NC_000017.10:g.42078967A>T (NM_153006.2:c.-3065A>T) and NC_000017.10:g.42078934C>T (NM_153006.2:c.-3098C>T) reside in the NAGS enhancer, within known HNF1 and predicted glucocorticoid receptor binding sites, respectively. Reporter gene assays in HepG2 and HuH-7 cells demonstrated that all four substitutions could result in reduced expression of NAGS. These findings show that analyzing noncoding regions of NAGS and other urea cycle genes can reveal molecular causes of disease and identify novel regulators of ureagenesis.

Network Modeling Sex Differences in Brain Integrity and Metabolic Health.

Hypothesis-driven studies have demonstrated that sex moderates many of the relationships between brain health and cardiometabolic disease, which impacts risk for later-life cognitive decline. In the present study, we sought to further our understanding of the associations between multiple markers of brain integrity and cardiovascular risk in a midlife sample of 266 individuals by using network analysis, a technique specifically designed to examine complex associations among multiple systems at once. Separate network models were constructed for male and female participants to investigate sex differences in the biomarkers of interest, selected based on evidence linking them with risk for late-life cognitive decline: all components of metabolic syndrome (obesity, hypertension, dyslipidemia, and hyperglycemia); neuroimaging-derived brain-predicted age minus chronological age; ratio of white matter hyperintensities to whole brain volume; seed-based resting state functional connectivity in the Default Mode Network, and ratios of N-acetyl aspartate, glutamate and myo-inositol to creatine, measured through proton magnetic resonance spectroscopy. Males had a sparse network (87.2% edges = 0) relative to females (69.2% edges = 0), indicating fewer relationships between measures of cardiometabolic risk and brain integrity. The edges in the female network provide meaningful information about potential mechanisms between brain integrity and cardiometabolic health. Additionally, Apolipoprotein ϵ4 (ApoE ϵ4) status and waist circumference emerged as central nodes in the female model. Our study demonstrates that network analysis is a promising technique for examining relationships between risk factors for cognitive decline in a midlife population and that investigating sex differences may help optimize risk prediction and tailor individualized treatments in the future.

Application of Next Generation Sequencing Genetic Studies of Urea Cycle Disorders

Urea cycle disorder is a group of rare, inherited metabolic disorders in the pathway transforming ammonia to urea. The mutations in genes coding for 6 enzymes that are participated including carbamoyl phosphate synthase I (CPSI), ornithine transcarbamylase (OTC), argininosuccinate synthase (ASS1), argininosuccinate lyase (ASL), arginase (ARG1), and N-acetyl glutamate synthase (NAGS), and 2 transport systems ((ornithine translocase (ONT1), citrin)) in the urea cycle are responsible for ammonia accumulation in the blood. Hyperammonemia is the cause of severe neurological symptoms and even death. In almost all cases, clinical examinations and biochemical experiments are necessary, but insufficient information for an accurate diagnosis. Mutation analysis is an effective method to confirm the diagnosis and could be the basis for genetic counseling. The rapid development and widely using of next generation sequencing (NGS) have brought incredible advances in molecular diagnosis of genetic diseases in general. In this article, we systematize the UCD genetic studies applying NGS method, thereby providing a basis for not only disease diagnosis but also future research

Kinetic Characterization of a Short N‐acetyl Glutamate Synthase from Alicyclobacillus acidocaldarius

N-acetyl glutamate synthase (NAGS) is the first enzyme in the arginine biosynthetic pathway and catalyzes the transfer of an acetyl group from acetyl-CoA to L-glutamate to produce N-acetylglutamate (NAG). NAGS enzymes either consist of two domains (classical NAGS) or a single domain (short NAGS or S-NAGS). S-NAGS, although present in many bacteria, have not been well characterized to date. This study's focus is to kinetically characterize putative S-NAGS from Alicyclobacillus acidocaldarius. Initial kinetics demonstrated low activity with L-glutamine (Km = 135 mM, kcat = 0.0631 s-1, and kcat/Km = 0.4674 M-1s-1) and L-glutamate (Km too large to determine, kcat/Km = 1.7x10-4 M-1s-1) as substrates which is consistent with the only other characterization of an S-NAGS. Surprisingly, the enzyme is not inhibited by L-arginine like other NAGS enzymes and instead uses L-arginine as a substrate with a significantly greater efficiency than any other amino acid substrate (Km = 21 mM, kcat = 0.0192 s-1, and kcat/Km = 0.9143 M-1s-1). Preliminary studies indicate that the enzyme follows a sequential kinetic mechanism.

Final Health and Environmental Risk Assessment of Genetically Modified Soybean 356043

Soybean 356043 expresses both the gat gene from the soil bacterium Bacillus licheniformis and the gm - hra gene, an optimised form of the endogenous acetolactate synthase (als) coding sequence from soybean (Glycine max; gm). The encoded GAT4601 protein, glyphosate acetyltransferase, confers the ability to inactivate the active herbicidal substances glyphosate and glyphosate-ammonium to N-acetyl glyphosate, which does not have herbicidal activity. The encoded GM-HRA protein confers increased tolerance to the active, ALS-inhibiting, herbicidal substances chlorimuron, thifensulfuron and sulfonylureas. Bioinformatics analyses of the inserted DNA and flanking sequences in soybean 356043 have not indicated a potential production of putative harmful proteins or polypeptides caused by the genetic modification. Genomic stability of the functional insert and consistent expression of the gat gene, have been shown over several generations of soybean 356043. Data from several field trials performed in USA, Canada, Chile and Argentina during 2005-2006 show that soybean 356043 contains higher levels of especially the acetylated amino acid N-acetyl aspartate, but also N-acetyl glutamate and the odd-chain fatty acids heptadecanoic, heptadecenoic and heptadecadienoic acids, in addition to expression of the newly expressed proteins. Otherwise the soybean 356043 is compositionally, morphologically and agronomically equivalent to its conventional counterpart and other commercial soybean cultivars. The acetylated amino acids and odd-chain fatty acids are normal constituents of plant and animal-derived foods and feeds, and an in-depth toxicity and intake assessment did not reveal safety concerns regarding consumer intake at the levels present in soybean 356043. Sub-chronic feeding studies with rats, repeated-dose toxicity studies with mice, as well as nutritional assessment trials with broilers and laying hens have not revealed adverse effects of soybean 356043. These studies indicate that soybean 356043 is nutritionally equivalent to and as safe as conventional soybean cultivars. The GAT4601 and GM-HRA proteins produced in soybean 356043 do not show sequence resemblance to known toxins or IgE-dependent allergens, nor has the whole GM plant been reported to cause changes in IgE-mediated allergic reactions in patients reactive to soybean or in non-ectopic control individuals. Soybean is not cultivated in Norway, and there are no cross-compatible wild or weedy relatives of soybean in Europe. &#x0D; &#x0D; Based on current knowledge and considering the intended uses, which exclude cultivation, the VKM GMO Panel concludes that soybean 356043 with the GAT4601 and GM-HRA proteins:&#x0D; &#x0D; - Is – with the exception of the novel traits and resulting increased content of the acetylated amino acids NAA and NAG, and the odd-chain fatty acids heptadecanoic, heptadecenoic and heptadecadienoic acids – compositionally, morphologically and agronomically equivalent to its conventional counterpart and other commercial soybean cultivars&#x0D; - Are unlikely to introduce toxic or allergenic potentials in food or feed compared to conventional soybean cultivars&#x0D; - Is nutritionally equivalent to and as safe as its conventional counterpart and other conventional soybean cultivars&#x0D; - Does not represent an environmental risk in Norway.

3T MEGA-PRESS study of N-acetyl aspartyl glutamate and N-acetyl aspartate in activated visual cortex.

To measure N-acetyl aspartyl glutamate (NAAG) and N-acetyl aspartate (NAA) concentrations in visual cortex activated by a continuous stimulation in a 3T field. NAAG and NAA spectra were obtained with MEGA-PRESS pulse sequence (TE/TR = 140/2000ms; δONNAAG/δOFFNAAG = 4.61/4.15ppm; δONNAA/δOFFNAA = 4.84/4.38ppm) in 14 healthy volunteers at rest and upon stimulation by a radial checkerboard flickering at a frequency of 8Hz. Spectra of all subjects were frequency and phase aligned and then averaged. Additionally, to obtain the time-dependency data, spectra were divided into time sections of 64s each. The intensities of NAA, NAAG and lactate + macromolecular (Lac + MM) signals were defined by integration of the real part of spectra. The heights of the central resonance of NAAG and NAA signals were measured. The NAAG and NAA concentrations, measured with 2.5% and 0.5% error, respectively, were unaffected by visual activation. A significant increase in the Lac + MM signal by ~ 12% is clearly observed. No stimulation-induced time dependency was found for NAAG or NAA, while the increase in Lac + MM was gradual. The concentration values in visual cortex are in good agreement with the 7T MRS measurements: [NAAG] = 1.55mM, [NAA] = 11.95mM. The MEGA-PRESS pulse sequence together with the spectral preprocessing techniques allowed to demonstrate that the concentrations of NAAG and NAA in the visual cortex remain constant during continuous visual stimulation within the margin of error. An increase in the lactate signal intensity signifies the activation of the anaerobic glycolysis in activated visual cortex.

Computer Modeling of N-Acetylglutamate Synthase: From Primary Structure to Elemental Stages of Catalysis

Three-dimensional full-atom model of the enzyme complex with acetyl-CoA and substrate was constructed on the basis of the primary sequence of amino acid residues of N-acetyl glutamate synthase. Bioinformatics approaches of computer modeling were applied, including multiple sequence alignment, prediction of co-evolutionary contacts, and ab initio folding. On the basis of the results of calculations by classical molecular dynamics and combined quantum and molecular mechanics (QM/MM) methods, the structure of the active site and the reaction mechanism of N-acetylglutamate formation are described. Agreement of the structures of the enzyme-product complexes obtained in computer modeling and in the X-ray studies validates the reliability of modeling predictions.

Cognitive Performance and Neuro-Metabolites in HIV Using 3T Magnetic Resonance Spectroscopy: A Cross-Sectional Study from India.

Cognitive impairment in patients with human immunodeficiency virus (HIV) is associated with higher morbidity. The prevalence of the metabolite changes in the brain associated with cognitive impairment in anti-retroviral therapy naïve patients with HIV is unknown. To estimate the prevalence of the neurometabolites associated with cognitive impairment in antiretroviral therapy (ART) naïve patients with HIV. We conducted a cross-sectional study among ART naïve patients with HIV aged 18-50 years in a tertiary care center in India. Cognition was tested using the Post Graduate Institute battery of brain dysfunction across five domains; memory, attention-information processing, abstraction executive, complex perceptual, and simple motor skills. We assessed the total N-acetyl aspartyl (tNAA), creatine (tCr) and glutamate + glutamine (Glx) using 3T magnetic resonance spectroscopy. Cognitive impairment was defined as an impairment in ≥2 domains. Among 43 patients eligible for this study, the median age was 32 years (IQR 29, 40) and 30% were women. Median CD4 count and viral load were 317 cells/μL (IQR 157, 456) and 9.3 copies/ μL (IQR 1.4, 38), respectively. Impairment in at least one cognitive domain was present in 32 patients (74.4%). Impairment in simple motor skills and memory was present in 46.5% and 44% of patients, respectively. Cognitive impairment, defined by impairment in ≥2 domains, was found in 22 (51.2%) patients. There was a trend towards higher concentration of tNAA (7.3 vs. 7.0 mmol/kg), tGlx (9.1 vs. 8.2 mmol/kg), and tCr (5.5 vs. 5.2 mmol/kg) in the frontal lobe of patients with cognitive impairment vs. without cognitive impairment but it did not reach statistical significance (p>0.05 for all). There was no difference in the concentration of these metabolites in the two groups in the basal ganglia. There is a high prevalence of cognitive impairment in ART naïve patients with HIV. There is no difference in metabolites in patients with or without cognitive impairment. Further studies, with longitudinal follow-up are required to understand the underlying pathophysiological mechanisms.

Effects of sulforaphane on cognitive function in patients with frontal brain damage: study protocol for a randomised controlled trial

IntroductionMany patients with frontal brain damage show serious cognitive function deficits, which hamper their quality of life and result in poor clinical outcomes. Preclinical research has shown that sulforaphane can...

High-level production of ornithine by expression of the feedback inhibition-insensitive N-acetyl glutamate kinase in the sake yeast Saccharomyces cerevisiae

We previously reported that intracellular proline (Pro) confers tolerance to ethanol on the yeast Saccharomyces cerevisiae. In this study, to improve the ethanol productivity of sake, a traditional Japanese alcoholic beverage, we successfully isolated several Pro-accumulating mutants derived from diploid sake yeast of S. cerevisiae by a conventional mutagenesis. Interestingly, one of them (strain A902-4) produced more than 10-fold greater amounts of ornithine (Orn) and Pro compared to the parent strain (K901). Orn is a non-proteinogenic amino acid and a precursor of both arginine (Arg) and Pro. It has some physiological functions, such as amelioration of negative states such as lassitude and improvement of sleep quality. We also identified a homo-allelic mutation in the ARG5,6 gene encoding the Thr340Ile variant N-acetylglutamate kinase (NAGK) in strain A902-4. The NAGK activity of the Thr340Ile variant was extremely insensitive to feedback inhibition by Arg, leading to intracellular Orn accumulation. This is the first report of the removal of feedback inhibition of NAGK activity in the industrial yeast, leading to high levels of intracellular Orn. Moreover, sake and sake cake brewed with strain A902-4 contained 4–5 times more Orn than those brewed with strain K901. The approach described here could be a practical method for the development of industrial yeast strains with overproduction of Orn.

Molecular docking studies of natural compounds of naringin on enzymes involved in the urea cycle pathway in hyperammonemia

Purpose: To investigate the anti-hyperammonemic activity of naringin by molecular docking via in silico studies.Methods: Urea cycle proteins were docked to the natural compound naringin as well as a standard drug, sodium benzoate. Hydrogen bonds and binding energy were obtained using Catalytic Site Atlas and Cast P Finder Software Tool.Results: There were six urea cycle enzymes, including N-acetyl glutamate synthase, carbamoyl phosphate synthase I, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase and arginase I. On evaluating protein interactions with naringin, which is dynamically connected to the urea cycle pathway with hyperammonemia, naringin showed more hydrogen bonds and also produced higher binding energy when compared to the standard drug, sodium benzoate.Conclusion: The results of the molecular docking study show that naringin interacts with urea cycle enzymes with more hydrogen bonds and higher bonding energy than the standard drug, sodium benzoate. This supports the hypothesis that naringin can prevent experimental hyperammonemia.&#x0D; Keywords: Naringin, Sodium benzoate, Hyperammonemia, Urea cycle enzymes, In silico studies&#x0D;

Separate N-acetyl aspartyl glutamate, N-acetyl aspartate, aspartate, and glutamate quantification after pediatric mild traumatic brain injury in the acute phase.

To separately measure N-acetyl aspartul glutamate (NAAG), N-acetyl aspartate (NAA), aspartate (Asp), and glutamate (Glu) concentrations in white matter (WM) using J-editing techniques in patients with mild traumatic brain injury (mTBI) in the acute phase. Twenty-four patients with closed concussive head injury and 29 healthy volunteers were enrolled in the current study. For extended 1 H MRS examination, patients and controls were equally divided into two subgroups. In subgroup 1 (12 patients/15 controls), NAAG and NAA concentrations were measured in WM separately with MEGA-PRESS (echo time/repetition time [TE/TR] = 140/2000 ms; / = 4.84/4.38 ppm, / = 4.61/4.15 ppm). In subgroup 2 (12 patients/14 controls), Asp and Glu concentrations were acquired with MEGA-PRESS (TE/TR = 90/2000 ms; / = 3.89/5.21 ppm) and TE-averaged PRESS (TE from 35 ms to 185 ms with 2.5-ms increments; TR = 2000 ms) pulse sequences, respectively. tNAA and NAAG concentrations were found to be reduced, while NAA concentrations were unchanged, after mild mTBI. Reduced Asp and elevated myo-inositol (mI) concentrations were also found. The main finding of the study is that the tNAA signal reduction in WM after mTBI is associated with a decrease in the NAAG concentration rather than a decrease in the NAA concentration, as was thought previously. This finding highlights the importance of separating these signals, at least for WM studies, to avoid misinterpretation of the results. NAAG plays an important role in selectively activating mGluR3 receptors, thus providing neuroprotective and neuroreparative functions immediately after mTBI. NAAG shows potential for the development of new therapeutic strategies for patients with injuries of varying severity.