Remember the new Special Issue!
The Editor’s pick selection of the most intriguing papers is highlighted in yellow.
D-AAs AND PHYSIOLOGICAL:
Sensory ataxia and cardiac hypertrophy caused by neurovascular oxidative stress in chemogenetic transgenic mouse lines
Yadav S., Waldeck-Weiermair M., Spyropoulos F., Bronson R., Pandey A.K., Das A.A., Sisti A.C., Covington T.A., Thulabandu V., Caplan S., Chutkow W., Steinhorn B., Michel T.
(2023) Nature Communications, 14 (1), art. no. 3094. DOI: 10.1038/s41467-023-38961-0
The neurovascular oxidative stress was studied in chemogenetic transgenic mouse lines expressing yeast D-amino acid oxidase (DAAO) in neurons and vascular endothelium (thus generating hydrogen peroxide when fed with D-amino acids). By providing D-alanine, these mice rapidly developed sensory ataxia caused by oxidative stress and mitochondrial dysfunction in neurons within dorsal root ganglia and nodose ganglia innervating the heart. Furthermore, these mice also developed cardiac hypertrophy after chronic chemogenetic oxidative stress. Notably, this situation is similar to findings in patients with Friedreich’s ataxia. The authors concluded that neurovascular oxidative stress is sufficient to cause sensory ataxia and cardiac hypertrophy.
D-Asparagine is an Ideal Endogenous Molecule for Measuring the Glomerular Filtration Rate
Taniguchi A., Kawamura M., Sakai S., Kimura-Ohba S., Tanaka Y., Fukae S., Tanaka R., Nakazawa S., Yamanaka K., Horio M., Takahara S., Nonomura N., Isaka Y., Imamura R., Kimura T.
(2023) Kidney International Reports, 8 (6), pp. 1192 – 1200. DOI: 10.1016/j.ekir.2023.03.009
This work focused on the potential of D-amino acids for kidney function assessment. Multivariate analysis identified the blood level of D-asparagine (D-Asn) to reflect glomerula filtration rate (GFR): means of blood D-Asn and its clearance were 0.21 μM and 65.0 mL/min per 1.73 m2, respectively. The authors concluded that D-Asn acts similar to inulin in the kidney, thus representing an ideal endogenous compound that can be used for GFR measurement.
Chiral Amino Acid Profiling in Serum Reveals Potential Biomarkers for Alzheimer’s Disease
Liu M, Li M, He J, He Y, Yang J, Sun Z
J Alzheimers Dis. 2023;94(1):291-301. doi: 10.3233/JAD-230142.
This study investigated the levels of amino acids, especially D-amino acids, in the peripheral serum of AD patients, by HPLC-MS/MS analysis. D-Proline, D/total-proline ratio, D-aspartate, and D/total-aspartate ratio were decreased, while D-phenylalanine was elevated in AD compared to healthy controls. Significant age-dependent increases in D-proline, D/total-proline ratio, and D-phenylalanine were observed in controls, but not in AD. The combination of D-proline, D-aspartate, D-phenylalanine, and age for discriminating AD from controls provided satisfactory area under the curve (0.87), specificity (97.0%), and sensitivity (83.8%). Furthermore, the D-aspartate level was significantly decreased with the progression of AD, as assessed by the Clinical Dementia Rating Scale and Mini-Mental State Examination.
Differential relationships of NMDAR hypofunction and oxidative stress with cognitive decline
Lane HY, Wang SH, Lin CH
Psychiatry Res. 2023 Jun 10;326:115288. doi: 10.1016/j.psychres.2023.115288. Online ahead of print.
NMDAR hypofunction and oxidative stress are implicated in the pathogenesis of Alzheimer’s disease. This study explored the associations of DAAO, glutathione, superoxide dismutase (SOD), and catalase as potential biomarkers with mild cognitive impairment. Cognitive function and blood levels of DAAO, glutathione, SOD, and catalase were measured in 63 mild cognitive impairment patients and 24 healthy individuals every 6 months for 2 years. Among the patients, DAAO and glutathione levels at baseline contributed to the cognitive decline 2 years later. Among the healthy individuals, only glutathione levels were associated with cognitive change. Among patients, glutathione levels were negatively correlated with SOD and positively correlated with catalase, and DAAO levels were negatively correlated with SOD. The authors concluded that glutathione may be regarded as an aging marker for both mild cognitive impairment and normal aging, while DAAO could represent a biomarker exclusively for mild cognitive impairment.
Luvadaxistat: A Novel Potent and Selective D-Amino Acid Oxidase Inhibitor Improves Cognitive and Social Deficits in Rodent Models for Schizophrenia
Fradley R, Goetghebeur P, Miller D, Burley R, Almond S, Gruart I Massó A, Delgado García JM, Zhu B, Howley E, Neill JC, Grayson B, Gaskin P, Carlton M, Gray I, Serrats J, Davies CH
Neurochem Res. 2023 Jun 8. doi: 10.1007/s11064-023-03956-2. Online ahead of print.
N-methyl-D-aspartate (NMDA) receptor hypofunctionality is a well-studied hypothesis for schizophrenia pathophysiology. Inhibition of D-amino acid oxidase (DAAO) has the potential to be a new therapeutic approach for the treatment of schizophrenia by increasing the levels of the co-agonist D-serine. TAK-831 (luvadaxistat), a potent inhibitor of DAAO, significantly increases D-serine levels in the rodent brain, plasma, and cerebrospinal fluid. Luvadaxistat is efficacious in animal tests of cognition and in a translational animal model for cognitive impairment in schizophrenia, especially when luvadaxistat is dosed alone and in conjunction with a typical antipsychotic. When dosed chronically, there is a suggestion of change in synaptic plasticity. While luvadaxistat ameliorated the deficit seen in sociability in two different negative symptom tests of social interaction, it failed to show an effect in endpoints of negative symptoms in clinical trials.
Mass spectrometry-based untargeted metabolomics study of non-obese individuals with non-alcoholic fatty liver disease
Demirel M, Köktaşoğlu F, Özkan E, Dulun Ağaç H, Gül AZ, Sharifov R, Sarıkaya U, Başaranoğlu M, Selek Ş
Scand J Gastroenterol. 2023 Jun 20:1-7. doi: 10.1080/00365521.2023.2225667. Online ahead of print.
Non-alcoholic fatty liver disease (NAFLD) is characterized by the accumulation of excessive fat in the liver, which can lead to fibrosis; it can also occur in non-obese/non-overweight individuals. By using liquid chromatography-high resolution mass spectrometry, the metabolic profiling of non-obese NAFLD patients and healthy controls were investigated. Significant changes in D-amino acid
metabolism, vitamin B6 metabolism, apoptosis, mTOR signaling pathway, lysine degradation, and phenylalanine metabolism pathways were apparent in non-obese NAFLD patients. Significant changes were also observed in the metabolites D-pantothenic acid, hypoxanthine, citric acid, citramalic acid, L-phenylalanine, glutamine, and histamine-trifluoromethyl-toluidide, β-hydroxymyristic acid, DL-lactic acid, and 3-methyl-2-oxopentanoic.
D-AAs AND BACTERIA:
Cooperative microbial interactions drive spatial segregation in porous environments
Wu Y, Fu C, Peacock CL, Sørensen SJ, Redmile-Gordon MA, Xiao KQ, Gao C, Liu J, Huang Q, Li Z, Song P, Zhu Y, Zhou J, Cai. P
Nat Commun. 2023 Jul 15;14(1):4226. doi: 10.1038/s41467-023-39991-4.
In this work a microfluidic chip was used to represent porous subsurface environments and show that cooperative microbial interactions between free-living and biofilm-forming bacteria trigger active spatial segregation to promote their respective dominance in segregated microhabitats. During initial colonization, free-living and biofilm-forming microbes are segregated from the mixed planktonic inoculum to occupy the ambient fluid and grain surface. The active spatial segregation is induced by cooperative interactions which improves the fitness of both biofilm and planktonic populations. The free-living Arthrobacter induces the surface colonization by scavenging the biofilm inhibitor, D-amino acids and receives benefits from the public goods secreted by the biofilm-forming strains.
Gut Protective Effect from D-Methionine or Butyric Acid against DSS and Carrageenan-Induced Ulcerative Colitis
Ikeda, Y.; Matsuda, S.
Molecules 2023, 28, 4392. https://doi.org/10.3390/molecules28114392
Microbiome dysbiosis may be associated with diseases, such as inflammatory bowel diseases (IBD), which are characterized by active intestinal inflammation. This work evaluated the potential gut protective effects of D-methionine (D-Met) and/or butyric acid (BA) in an IBD mouse model, and revealed that supplementation of both molecules resulted in the attenuation of the disease condition as well as the suppression of several inflammation-related gene expressions in the IBD mouse model.
Non disseminative nano-strategy against in vivo Staphylococcus aureus biofilms
Pinto R.M., Yazdani S., Seabra C.L., De Jonge M., Izci M., Cruz R., Casal S., Soenen S.J., Reis S., Nunes C., Van Dijck P.
(2023) npj Biofilms and Microbiomes, 9 (1), art. no. 39 DOI: 10.1038/s41522-023-00405-4
This work proposes the development of lipid nanoparticles (NP) encapsulating caspofungin (CAS) as a matrix-disruptive nanosystem for Staphylococcus aureus. NPs were functionalized with D-amino acids to target the matrix. CAS-loaded NPs were combined with a moxifloxacin-loaded nanosystem, as an adjuvant to promote the EPS matrix disruption. In vitro and in vivo studies demonstrated biofilm reduction when the two nanosystems were used. The in vivo biodistribution revealed the ability of the nanosystems to reach and accumulate in the biofilm region, after intraperitoneal administration.
Biofouling mitigation by D-tyrosine in membrane bioreactor: Short-term performance
Su X., Luo J., Wang Y., Dong J., Tian Y.
(2023) Journal of Environmental Chemical Engineering, 11 (2), art. no. 109554. DOI: 10.1016/j.jece.2023.109554
D-amino acids can inhibit the formation of biofilm without affecting bacterial growth. The effects of D-tyrosine (D-Tyr) on the performance of membrane bioreactor (MBR) during short-term operation were investigated here. The critical flux of activated sludge in MBR increased with the existence of D-Tyr, while the removal efficiencies of wastewater were not affected. The fouling propensities of soluble microbial products (SMP) in both MBRs were almost the same. Extracellular polymeric substance (EPS) exhibited weaker fouling propensity when D-Tyr was used, a treatment that did not affect SMP. D-Tyr lead to the reduction of EPS polysaccharides and the great fluctuation of EPS protein, as well as altered the microbial community structure in MBR, which could be relevant for the change of EPS.
L-Alanine Exporter AlaE Functions as One of the D-Alanine Exporters in Escherichia coli
Katsube S, Sakai K, Ando T, Tobe R, Yoneyama H
Int J Mol Sci. 2023 Jun 16;24(12):10242. doi: 10.3390/ijms241210242.
Recently, Escherichia coli has been found to possess one or more energy-dependent D-alanine export systems. A novel screening system in which cells expressing a putative D-alanine exporter could support the growth of D-alanine auxotrophs in the presence of L-alanyl-L-alanine was proposed. In the initial screening, five D-alanine exporter candidates, were identified. By a number of different approaches, the authors concluded that YciC could function as a D-alanine exporter in intact cells.
D-amino acids signal a stress-dependent run-away response in Vibrio cholerae
Irazoki O, Ter Beek J, Alvarez L, Mateus A, Colin R, Typas A, Savitski MM, Sourjik V, Berntsson RP, Cava F
Nat Microbiol. 2023 Jun 26. doi: 10.1038/s41564-023-01419-6. Online ahead of print.
To explore favourable niches while avoiding threats, many bacteria use a chemotaxis navigation system. Many bacterial species release D-amino acids to the environment. This work reports that D-arginine and D-lysine are chemotactic repellent signals for the cholera pathogen Vibrio cholerae. These D-amino acids are sensed by a single chemoreceptor MCPDRK co-transcribed with the racemase enzyme that synthesizes them under the control of the stress-response sigma factor RpoS. Structural characterization of this chemoreceptor was reported. Indeed, the specificity for these D-amino acids appears to be restricted to those MCPDRK orthologues transcriptionally linked to the racemase.
D-AAs & BIOTECHNOLOGY:
Rapid and universal quantification of viable bacteria with growth activity in raw milk using a fluorescent D-amino acid-flow cytometry (FDAA-FCM) method
Wang M., Bai Z., Liu S., Fu B., Liu Y., Wang Z., Zhou G., Gong X., Jiang Y., Sui Z.
(2023) LWT, 184, art. no. 114998 DOI: 10.1016/j.lwt.2023.114998ù
This study focused on the use of fluorescent D-amino acid (FDAA)-based labeling, targeting viable bacteria, in conjunction with typical bacterial species found in milk as an alternative method to the plate counting method commonly used to evaluate the total bacterial count (TBC). By optimizing the FDAA labeling and cell division inhibition conditions and integrating with flow cytometry, the rapid quantification of viable bacteria with growth activity was performed. The authors quantified viable bacteria in real milk samples with a TBC > 90000 cells/mL within a timeframe of 2.5 hours.
Regio- and stereo-selective amination of fatty acids to D-amino acids by a three-step one-pot cascade
Yu X., Chen X.-Y., Yu H.-L., Xu J.-H., Zhang Z.-J.
(2023) Green Chemistry, 25 (9), pp. 3469 – 3474. DOI: 10.1039/d3gc00782k
This work focused on a three-step one-pot multienzyme cascade for the asymmetric synthesis of D-amino acids from renewable fatty acids. The cascade system employed P450 peroxygenase with two enantio-complementary hydroxyacid oxidase(s) to the regioselective oxyfunctionalization of fatty acids into prochiral α-ketoacids with internal hydrogen peroxide recycling. An engineered D-amino acid dehydrogenase with formate dehydrogenase activity was used for self-recycling the expensive cofactor NADPH. Different fatty acids (C6-C10) were converted into the corresponding D-amino acids with high yield (up to 99%) and excellent ee value (>99%).
The D-amino acid oxidase-carbon nanotubes: evaluation of cytotoxicity and biocompatibility of a potential anticancer nanosystem
Rosini E., Boreggio M., Verga M., Caldinelli L., Pollegioni L., Fasoli E.
(2023) 3 Biotech, 13 (7), art. no. 243. DOI: 10.1007/s13205-023-03568-1
The ‘enzyme prodrug therapy’ based on D-amino acid oxidase (DAAO) uses the production of hydrogen peroxide, a reactive oxygen species (ROS), to favor cancer cells death. Recently, multi-walled carbon nanotubes (MWCNTs) were functionalized with polyethylene glycol (PEG) to reduce their tendency to aggregation and to improve their biocompatibility. Here, wtDAAO and mDAAO variants were adsorbed on PEGylated MWCNTs. While PEG-MWCNTs-DAAOs showed a higher activity than pristine MWCNTs-DAAO (independently on the DAAO variant used), PEG-MWCNTs-mDAAO showed a higher cytotoxicity than PEG-MWCNTs-wtDAAO at low oxygen concentration. Following PEG-MWCNTs-DAAOs incubation in human serum, the composition of protein corona was investigated via nLC-MS/MS. The mDAAO variant has influenced the bio-corona composition in both number of proteins and presence of opsonins and dysopsonins: notably, the soft corona of PEG-MWCNTs-mDAAO contained less proteins and was more enriched in proteins able to inhibit the immune response than PEG-MWCNTs-wtDAAO. Altogether, the PEGylated MWCNTs conjugated with the mDAAO variant seems a promising candidate for a selective antitumor oxidative therapy.
D- and N-Methyl Amino Acids for Modulating the Therapeutic Properties of Antimicrobial Peptides and Lipopeptides
Humpola M.V., Spinelli R., Erben M., Perdomo V., Tonarelli G.G., Albericio F., Siano A.S.
(2023) Antibiotics, 12 (5), art. no. 821. DOI: 10.3390/antibiotics12050821
Analogs of two antimicrobial peptides, namely C10:0-A2, a lipopeptide, and TA4, a cationic α-helical amphipathic peptide, were produced (and analyzed) using non-proteinogenic amino acids to improve their therapeutic properties. This study reports that substitution with D- and N-methyl amino acids could be a useful strategy to modulate the therapeutic properties of antimicrobial peptides and lipopeptides, including enhancing stability against enzymatic degradation. The study provides insights into the design and optimization of antimicrobial peptides to achieve improved stability and therapeutic efficacy.
Development of an aminotransferase-driven biocatalytic cascade for deracemization of D,L-phosphinothricin
Liu HL, Wu JM, Deng XT, Yu L, Yi PH, Liu ZQ, Xue YP, Jin LQ(1)(2)(3), Zheng YG
Biotechnol Bioeng. 2023 May 25. doi: 10.1002/bit.28432. Online ahead of print.
2-Oxo-4-[(hydroxy)(methyl)phosphinoyl]butyric acid (PPO) is the precursor keto acid for the asymmetric biosynthesis of herbicide L-phosphinothricin (L-PPT). In this paper, a D-amino acid aminotransferase from Bacillus sp. YM-1 (Ym DAAT) was evaluated. To avoid the inhibition of by-product D-glutamate, an amino acceptor (α-ketoglutarate) regeneration cascade was constructed as a recombinant Escherichia coli by coupling Ym D-AAT, D-aspartate oxidase from Thermomyces dupontii (TdDDO) and catalase from Geobacillus sp. CHB1. The aminotransferase-driven whole-cell biocatalytic cascade showed superior catalytic efficiency for the synthesis of PPO from D,L-phosphinothricin.
IPTG-induced high protein expression for whole-cell biosynthesis of L-phosphinothricin
Xu JM, Wu ZS, Zhao KJ, Xi ZJ, Wang LY, Cheng F, Xue YP, Zheng YG
Biotechnol J. 2023 Jun 2:e2300027. doi: 10.1002/biot.202300027. Online ahead of print.
In this work, an Escherichia coli strain coexpressing of D-amino acid oxidase and catalase (E. coli DAAO-CAT) was used to oxidize D-PPT to PPO, and then use the second E. coli strain coexpressing glutamate dehydrogenase and formate dehydrogenase (E. coli GluDH-FDH) to reduce biocatalytic PPO to L-PPT. The best induction conditions for E. coli DAAO-CAT were determined , as well as for E. coli GluDH-FDH. Under optimized conditions 200 mM D-PPT was converted by E. coli DAAO-CAT in 4 h (conversion rate of over 99.0%). Then, 220 mM PPO was converted to L-PPT by E. coli GluDH-FDH in 3 h (conversion rate of over 99.0%)
Oxygen-consumption based quantification of chemogenetic H2O2 production in live human cells
den Toom WTF, van Soest DMK, Polderman PE, van Triest MH, Bruurs LJM, De Henau S, Burgering BMT, Dansen TB
Free Radic Biol Med. 2023 Jun 29;206:134-142. doi:10.1016/j.freeradbiomed.2023.06.030. Online ahead of print.
D-Amino acid oxidase (DAAO) catalyzes hydrogen peroxide formation from D-amino acids, molecules normally absent from culture media. DAAO ectopic expression has been used in several studies to produce inducible and titratable intracellular hydrogen peroxide, although its precise quantification is a difficult task. In this paper, the oxygen consumption rate of DAAO was directly compared to the basal mitochondrial respiration in the same assay, to estimate whether the ensuing level of hydrogen peroxide production is within the range of physiological mitochondrial ROS production. This assay can also be used to select clones that express differentially localized DAAO with the same absolute level of hydrogen peroxide production, in order to discriminate the effects of hydrogen peroxide production at different subcellular locations from differences in total oxidative burden.
Stereoisomer-Dependent Membrane Association and Capacity for Insulin Delivery Facilitated by Penetratin
Birch D, Sayers EJ, Christensen MV, Jones AT, Franzyk H, Nielsen HM
Pharmaceutics. 2023 Jun 7;15(6):1672. doi: 10.3390/pharmaceutics15061672.
This work compared membrane association, cellular uptake, and delivery capacity for all-L and all-D-enantiomers of penetratin (PEN) by using different cell models and cargos. The results showed that while D-PEN was associated with the plasma membrane to a larger extent and was superior in mediating the transepithelial delivery of hydrophilic peptide cargoes compared to L-PEN across Caco-2 epithelium, no enhanced delivery of the hydrophobic cyclosporin was observed, and intracellular insulin uptake was induced to a similar degree by the two enantiomers.
Design of an Arabidopsis thaliana reporter line to detect heat-sensing and signaling mutants
Guihur A., Bourgine B., Rebeaud M.E., Goloubinoff P.
(2023) Plant Methods, 19 (1), art. no. 56. DOI: 10.1186/s13007-023-01033-x
In this paper, a heat-responsive Arabidopsis thaliana reporter line that allows an in-depth investigation of the mechanisms underlying the accumulation of protective heat-shock proteins (HSPs) in response to high temperature was set up. A transgenic Arabidopsis thaliana reporter line named “Heat-Inducible Bioluminescence And Toxicity” (HIBAT) was designed to express from a conditional heat-inducible promoter, a fusion gene encoding for nanoluciferase and D-amino acid oxidase, whose expression is toxic in the presence of D-valine. At 22 °C, HIBAT seedlings grew unaffected by D-valine, and all survived iterative heat treatments in absence of the D-amino acid, 98% died following heat treatments on D-valine. HIBAT was considered a valuable candidate tool to identify Arabidopsis mutants defective in the response to high temperature stress.
Effect of Mini-PEGs Modification on the Enzymatic Digestion of D-Amino Acid-Containing Peptides under the Action of PROK
Yan L., Ke Y., Wang Y., Yang J., He Y., Wu L.
(2023) Chemistry – A European Journal, 29 (16), art. no. e202203524. DOI: 10.1002/chem.202203524
D-amino acid-containing peptides are known to resist enzymatic hydrolysis. This study investigated the influence of mini-PEGs modification on enzymatic hydrolysis ability of D-amino acid-containing peptides. PEGylation promoted enzymatic hydrolysis of the D-amino acid-containing peptide but did not alter the cleavage pattern. The computational simulations further showed that the enhanced enzymatic hydrolysis ability can be attributed to the strong interaction between the protease and the peptide after PEG3 modification and the resulting formation of a mature catalytic triad structure.
ENZYMES ACTIVE ON D-AAs:
The Symmetric Active Site of Enantiospecific Enzymes
Rosini E., Pollegioni L., Molla G.
(2023) Symmetry, 15 (5), art. no. 1017. DOI: 10.3390/sym15051017
This review focused on the enantiospecific interaction between proteins and chiral amino acids, introducing theoretical models and describing the molecular basis of the ability of relevant enzymes, such as amino acid oxidases, dehydrogenases, and aminotransferases, to discriminate the opposite enantiomers. The paper highlights the power of natural evolution in shaping biological processes: strictly enantioselective enzymes generated both through divergent evolution and convergent evolution, starting from different scaffolds: intriguingly, the active sites of these enzymes are frequently related by a mirror symmetry.
Effects of His-Tag Length on the Soluble Expression and Selective Immobilization of D-Amino Acid Oxidase from Trigonopsis variabilis: A Preliminary Study
Yan Z., Zhu Q., Ma L., Li G., Su E., Zeng J., Chen Y., Meng E., Deng S.
(2023) Processes, 11 (6), art. no. 1588 DOI: 10.3390/pr11061588
In this study, His-tags of varying lengths were fused to the N-terminus of D-amino acid oxidase (DAAO) from Trigonopsis variabilis. The tag length allowed to balance between cell growth and protein solubility, resulting in a higher volume activity, as well facilitated the enzyme immobilization onto a commercial epoxy carrier without metal bearing.
Mechanism of D-Cycloserine Inhibition of D-Amino Acid Transaminase from Haliscomenobacter hydrossis
Bakunova A.K., Matyuta I.O., Nikolaeva A.Y., Boyko K.M., Popov V.O., Yu. Bezsudnova E.
(2023) Biochemistry (Moscow), 88 (5), pp. 687 – 697. DOI: 10.1134/S0006297923050115
D-cycloserine inhibits pyridoxal-5′-phosphate (PLP)-dependent enzymes. This work investigated the mechanism of D-cycloserine inhibition of the PLP-dependent D-amino acid transaminase from Haliscomenobacter hydrossis. Spectral investigations, solution of the 3D structure of the complex with D-cycloserine, and kinetic experiments showed the molecular details of the interaction and that D-cycloserine inhibition is reversible (and reversed by adding excess of keto substrate or excess of cofactor).
D-AAs AND ANALYTICAL METHODS:
Differentiation of free D-amino acids and amino acid isomers in solution using tandem mass spectrometry of hydrogen-bonded clusters
Inoue K, Fujihara A
J Pharm Biomed Anal. 2023 Jul 10;234:115567. doi: 10.1016/j.jpba.2023.115567.
In this paper, free D-amino acids and amino acid enantiomers were differentiated using tandem mass spectrometry without chromatographic separation. Ultraviolet photodissociation and water adsorption of leucine and isoleucine enantiomers hydrogen-bonded with tryptophan were investigated at 8 K in the gas phase, and details have been reported. Calibration curves for the differentiation of isomeric amino acids and their enantiomers were developed monitoring isomer- and enantiomer-selective photodissociation, indicating that the molar fractions in solution could be determined from a single product ion spectrum.
The D-amino acids International Research Center “DAAIR“ has been established in Gerenzano (Varese, Italy) in 2019 with the aim to support and perform scientific research projects and activities on the field of D-amino acids. The Center, located inside the Fondazione Istituto Insubrico Ricerca per la Vita, is aimed to represent a pole of excellence at international level for dissemination and research involving the D-amino acids (Director Silvia Sacchi).
The guiding principle is support the research projects aimed to investigate the involvement of D-amino acids in main physiological processes, from bacteria to humans. The ultimate goal is to actively participate to the elucidation of the mechanisms by which the D-amino acids perform specific functions, and to identify their presence and concentration in different organisms and compartments, also with regards to well-established functional states, with particular emphasis to pathological states. Understand the involvement of D-amino acids in important diseases as a way to set up novel therapeutic strategies.
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