The 6th International Conference of D-Amino Acid Research (IDAR2024) and 18th Joint Conference of the D-Amino Acid Research Society Japan will be held at Kanazawa University in August 2024 between 21 (Wednesday) and 24 (Saturday). The website of IDAR2024 is open now, please visit the following:

Do you have news concerning the D-amino acids field to announce? Is there a relevant published paper to mention? Write us and take the advantage of this bimonthly Newsletter.





The Editor’s pick selection of the most intriguing papers is highlighted in yellow.


Investigating D-Amino Acid Oxidase Expression and Interaction Network Analyses in Pathways Associated With Cellular Stress: Implications in the Biology of Aging

Kalidasan V, Suresh D, Zulkifle N, Hwei YS, Kok Hoong L, Rajasuriar R, Theva Das K Bioinform Biol Insights. 2024;18:11779322241234772. eCollection 2024. This study focuses on the effect of D-amino acid oxidase (DAAO) knockdown using clustered regularly interspaced short palindromic repeats (CRISPR) through an in silico approach on its protein-protein interactions (PPIs) and their potential roles in the process of aging. The proteins predicted to interact with DAAO are involved in peroxisome pathways such as acyl-coenzyme A oxidase 1 (ACOX1), alanine-glyoxylate and serine-pyruvate aminotransferase (AGXT), catalase (CAT), carnitine O-acetyltransferase (CRAT), glyceronephosphate O-acyltransferase (GNPAT), hydroxyacid oxidase 1 (HAO1), hydroxyacid oxidase 2 (HAO2), trans-L-3-hydroxyproline dehydratase (L3HYPDH), polyamine oxidase (PAOX), and pipecolic acid and sarcosine oxidase (PIPOX). DAAO mutations would most likely reduce activity with its interacting proteins that generate H2O2, and this should be relevant in peroxisomal disorders.

D-Amino acids differentially trigger an inflammatory environment in vitro Yap S.H., Lee C.S., Zulkifli N.D., Suresh D., Hamase K., Das K.T., Rajasuriar R., Leong K.H. (2024) Amino Acids, 56 (1), DOI: 10.1007/s00726-023-03360-8

The catabolism of D-AAs by D-amino oxidase (DAAO) produces hydrogen peroxide, a ROS involved in several physiological processes including immune response, cell differentiation, and proliferation. Here, the molecular mechanisms of D-serine and D-alanine in human HepG2 liver cancer cells was studied. D-Ser decreased H2O2 production and induced concentration-dependent depolarization of mitochondrial membrane potential, with the upregulation of activated NF-кB, pro-inflammatory cytokine, TNF-α, and chemokine, IL-8 secretion, and subsequent apoptosis. Conversely, D-Ala-treated cells induced H2O2 production and upregulation of activated NF-кB, TNF-α, and IL-8, but did not cause significant apoptosis.

Design and rationale for an open-label, randomized, controlled pilot trial to evaluate the changes in blood uremic toxins in patients with chronic kidney disease by dietary therapy with sake lees

Tokumaru T, Toyama T, Nakade Y, Ogura H, Oshima M, Nakagawa S, Furuichi M, Kitajima S, Sakai N, Shimizu M, Iwata Y, Wada T Clin Exp Nephrol. 2024 Feb 10. doi: 10.1007/s10157-023-02450-x. Online ahead of print. Patients with chronic kidney disease (CKD) reportedly show dysbiosis, which increases the uremic toxin level in the intestine, and uremic toxins transfer into the blood, causing CKD progression. Sake lees, a traditional Japanese fermented food which contains D-alanine, may have a renoprotective effect. In this pilot study, 24 patients with CKD will receive standard CKD dietary therapy with an additional intake of 50 g of sake lees per day for 8 weeks.


Distribution and role of D-glutamate, a novel D-amino acid identified in animals, in the reproductive tissues of male kuruma prawn Marsupenaeus japonicus

Yoshikawa N., Yoshitomi N., Nakada K., Sawada N. Journal of Biochemistry 2024, 175 (1), 95100. DOI: 10.1093/jb/mvad072 The authors previously reported large amounts of free D-glutamate in the tissue of the male reproductive organs of Marsupenaeus japonicus. Here, the distribution and potential role of D-Glu and D-alanine in male reproductive tissues (testis, vas deferens and seminal receptacle) was studied at different growth stages. D-Glu total level was > 50% in these tissues. D-Glu level was the highest in the younger stage, suggesting a relevant role in the reproductive functions of M. japonicus.

Biosynthesis and Degradation of Free D-Amino Acids and Their Physiological Roles in the Periphery and Endocrine Glands

Katane M., Homma H. Biological and Pharmaceutical Bulletin 2024, 47(3), 562–579. DOI: 10.1248/bpb.b23-00485 This review focuses on recent advances in elucidating the physiological roles of D-amino acids, especially in the periphery and endocrine glands.

Characterization of polychaetes inhabiting estuaries and inner bays by composition analysis of amino acids and lactate enantiomers

Onozato M, Shinohara W, Osaka Y, Sakamoto T, Umino M, Nishigaki A, Okoshi K, Fukushima T Sci Rep. 2024 14(1):5494. doi: 10.1038/s41598-024-55861-5

The composition of free amino acids and lactate in polychaetes in river estuaries and inner bays was studied using chromatographic techniques. Both L-amino acids and D-amino acids (D-asparagine, D-alanine (D-Ala), D-serine, D-aspartic acid, and D-proline (D-Pro)) were detected,

D-Amino acid oxidase-derived chemogenetic oxidative stress: Unraveling the multi-omic responses to in vivo redox stress

Spyropoulos F, Michel T

Curr Opin Chem Biol. 2024 79:102438. doi: 10.1016/j.cbpa.2024.102438

Recombinant yeast D-amino acid oxidase (DAAO) has been exploited to modulate H₂O₂ in target cells and tissues. In vitro studies using cultured cells expressing recombinant DAAO have provided information on the intracellular transport and metabolism of H₂O₂, with great temporal and spatial resolution. In vivo studies using chemogenetic/transgenic animal models have explored the pathological effects of chronically elevated H₂O₂ in tissues, providing new insights into the adaptations to oxidative stress. This review focuses on new models of heart failure and neurodegeneration that leverage in vivo chemogenetic modulation of oxidative stress in target tissues to identify new therapeutic targets.

D-amino acids metabolism reflects the evolutionary origin of higher plants and their adaptation to the environment

Porras-Dominguez J, Lothier J, Limami AM, Tcherkez G Plant Cell Environ. 2024 Jan 22. doi: 10.1111/pce.14826. Online ahead of print.

The occurrence of D-amino acids in plants has been reported quite recently as well evidence for a role in various processes, including interaction with soil microorganisms or interference with cellular signalling. Systemic analysis of sequences associated with D-amino acid metabolism enzymes shows that they are not simply inherited from cyanobacterial metabolism. Regardless of evolutionary steps, enzymes of D-AA metabolism, such as D-amino acid transferases or racemases, have been retained by higher plants and have not simply been eliminated, so it is likely that they fulfil important metabolic roles such as serine, folate or plastid peptidoglycan metabolism.


Development of an Enzyme Cascade System for the Synthesis of Enantiomerically Pure D-Amino Acids Utilizing Ancestral L-Amino Acid Oxidase

Araseki H., Sugishima N., Chisuga T., Nakano S.

ChemBioChem (2024) DOI: 10.1002/cbic.202400036

Four enzymes, namely ancestral L-amino acid oxidase (AncLAAO-N4), D-amino acid dehydrogenase (DAADH), D-glucose dehydrogenase (GDH), and catalase were used to convert L-amino acids to corresponding keto acids, which are then stereo-selectively aminated to D-amino acids by DAADH using NADPH and NH4Cl, while H2O2 is decomposed by catalase and GDH regenerates NADPH from D-glucose. Five D-amino acids, including a D-Phe derivative, three D-Trp derivatives, and D-phenylglycine, were produced with high enantiopurity (>99 % ee) at a preparative scale.

Super-Resolution Microscopy of the Bacterial Cell Wall Labeled by Fluorescent D-Amino Acids

Zhang C., Manley S.

Methods in Molecular Biology 2024 2727, 83-94. DOI: 10.1007/978-1-0716-3491-2_7

Fluorescent D-amino acids (FDAAs) enable in situ visualization of bacterial cell wall synthesis via their incorporation into peptidoglycan (PG) crosslinks. When combined with super-resolution microscopy, FDAAs allow the details of cell wall synthesis to be resolved. In this paper the super-resolution method of single-molecule localization microscopy in conjunction with two newly synthesized FDAAs (sCy5DA and sCy5DL_amide) were used to resolve bacterial PG at the nanoscale in a variety of species, including Gram-negative, Gram-positive, and mycobacteria.

Development and Applications of D-Amino Acid Derivatives-based Metabolic Labeling of Bacterial Peptidoglycan

Zheng Y, Zhu X, Jiang M, Cao F, You Q, Chen X

Angew Chem Int Ed Engl. 2024 Jan 29:e202319400. doi: 10.1002/anie.202319400. Online ahead of print. The peptidoglycan (PG) biosynthesis machinery exhibits high tolerance to various D-amino acid derivatives, which can be specifically incorporated into and label the peptidoglycan of bacteria. This review paper introduces the metabolic labeling strategies of PG by using D-AA derivatives, including one-step and two-step strategies, as well as various applications of D-amino acid derivative-based metabolic labelling.

Metabolic labeling-mediated visualization, capture, and inactivation of Gram-positive bacteria via biotin-streptavidin interactions

Zheng Y, Jiang M, Zhu X, Chen Y, Feng L, Zhu H

Chem Commun (Camb). 2024. doi: 10.1039/d4cc00517a. Online ahead of print. A biotinylated D-amino acid probe capable of metabolically incorporating into bacterial PG demonstrated efficacy in imaging, capture, and targeted inactivation of Gram-positive bacteria through synergistic pairings with commercially available streptavidin-modified fluorescent dyes and nanomaterials. The versatility of the probe is underscored by its compatibility with a variety of commercially available streptavidin-modified reagents.


Immobilization of D-amino acid dehydrogenase from Ureibacillus thermosphaericus

Boros K., Gal L., Gal C.A., Wäscher M., Tomoiagă R.B., Toşa M.I., Pietruszka J., Bencze L.C. Process Biochemistry 2024 140, 45-55.

Immobilization of D-amino acid dehydrogenase from Ureibacillus thermosphaericus (UtDAADH) and its co-immobilization with the NADPH–regenerating glucose dehydrogenase (GDH) was studied. The best procedure was DAADH adsorbed onto the Purolite® resin: despite presenting significant drop of 60% specific activity over 10 reaction cycles, still provided similar conversions with the covalently immobilized variant. The DAADH–GDH co-immobilized system showed no activity loss over 10 reaction cycles, providing self-sufficient cofactor for biocatalysts only for limited cycles.

Multifunctional enzymes related to amino acid metabolism in bacteria

Miyamoto T

Biosci Biotechnol Biochem. 2024:zbae027. doi: 10.1093/bbb/zbae027. Online ahead of print.

In bacteria, D-amino acids are synthesized from L-amino acids by amino acid racemases and by D-amino acid aminotransferases. This review focuses on novel bacterial D-amino acid metabolic pathways, which involve amino acid racemases with broad substrate specificity as well as multifunctional enzymes with D-amino acid-metabolizing activity, with special focus on pathways in Escherichia coli and Thermotoga maritima.

Direct Detection of the α-Carbon Radical Intermediate Formed by OspD: Mechanistic Insights into Radical S-Adenosyl-L-methionine Peptide Epimerization

Walls WG, Vagstad AL, Delridge T, Piel J, Broderick WE, Broderick JB

J Am Chem Soc. 2024 146(8):5550-5559. doi: 10.1021/jacs.3c13829

OspD is a radical S-adenosyl-L-methionine (SAM) peptide epimerase that converts an isoleucine and valine of the OspA substrate to D-amino acids during biosynthesis of landornamide A. This study used site-directed mutagenesis, freeze-quench trapping, isotopic labeling, and electron paramagnetic resonance (EPR) spectroscopy to provide new insights into the OspD catalytic mechanism. The study provided direct evidence for the OspD-catalyzed peptide epimerization mechanism via a central Cα radical intermediate during RiPP maturation of OspA, a mechanism that may extend to other proteusin peptide epimerases.

Understanding activity-stability tradeoffs in biocatalysts by enzyme proximity sequencing

Vanella R, Küng C, Schoepfer AA, Doffini V, Ren J, Nash MA

Nat Commun. 2024 15(1):1807. doi: 10.1038/s41467-024-45630-3

Here, the development of enzyme proximity sequencing, a deep mutational scanning method that leverages peroxidase-mediated radical labeling with single cell fidelity to dissect the effects of thousands of mutations on stability and catalytic activity of oxidoreductase enzymes in a single experiment, was reported. Enzyme proximity sequencing was used to analyze how 6399 missense mutations influence folding stability and catalytic activity in Rhodotorula gracilis D-amino acid oxidase. The results demonstrate activity-based constraints that limit folding stability during natural evolution, and identify hotspots distant from the active site as candidates for mutations that improve catalytic activity without sacrificing stability.

Amino Acid Chirality: Stereospecific Conversion and Physiological Implications.

Das K, Balaram H, Sanyal K

ACS Omega. 2024 9(5):5084-5099. doi: 10.1021/acsomega.3c08305

The occurrence of both L- and D-enantiomers of amino acids in the living systems necessitates the presence of enzymes that exhibit stereoselectivity in recognition of substrates. This review summarizes the overall mechanistic insights into the interconversion of L- and D-AAs by amino acid racemases, the physiological implications of D-amino acid oxidase and D-aspartate oxidase in human health and diseases and their applications as drug targets, and the potential applications of microbial chiral-selective enzymes as biocatalysts.


D-Histidine combated biofilm formation and enhanced the effect of amikacin against Pseudomonas aeruginosa in vitro

Zhang H, Mi Z, Wang J, Zhang J

Arch Microbiol. 2024 206(4):148. doi: 10.1007/s00203-024-03918-4

Pseudomonas aeruginosa is an opportunistic Gram-negative pathogenic microorganism: antibiotics exhibit limited efficacy against mature biofilm. D-histidine has been previously identified as an anti-biofilm agent. Here, the authors reported that D-His downregulated the mRNA expression of virulence and quorum sensing-associated genes in Pseudomonas aeruginosa PAO1 without affecting bacterial growth, significantly reduced the motility and pathogenicity, inhibited biofilm formation and triggered the disassembly of mature biofilms. Furthermore, D-His increased the susceptibility of PAO1 to amikacin allowing to propose the combination of amikacin and D-His against Pseudomonas aeruginosa biofilms.

Functional characterization of the dbu locus for D-branched-chain amino acid catabolism in Pseudomonas putida

Fulton RL, Downs DM

Appl Environ Microbiol. 2024 90(2):e0196223. doi: 10.1128/aem.01962-23

In Pseudomonas putida the dbu locus encodes a transcriptional regulator (DbuR), D-amino acid oxidase (DbuA), Rid2 protein (DbuB), and a putative transporter (DbuC), and is annotated as implicated in the utilization of D-arginine. This study showed that genes in the dbu locus are not required for D-Arg utilization, but they are involved in the catabolism of multiple D-branched-chain amino acids (D-BCAA). The oxidase DbuA was required for catabolism of each D-BCAA and D-phenylalanine, while the requirements for DbuC and DbuB were less stringent. This work expands our understanding of the metabolic network of Pseudomonas putida.

Poly(D-amino acid) Nanoparticles Target Staphylococcal Growth and Biofilm Disassembly by Interfering with Peptidoglycan Synthesis

Feng W, Chittò M, Xie W, Ren Q, Liu F, Kang X, Zhao D, Li G, Moriarty TF, Wang X

ACS Nano. 2024 18(11):8017-8028. doi: 10.1021/acsnano.3c10983

In this paper, 3D poly(D-amino acid) nanoparticles (NPs), which possess the ability to block intracellular metabolism, were produced for biofilm disassembling. The obtained poly(α-N-acryloyl-D-phenylalanine)-block-poly(β-N-acryloyl-D-aminoalanine NPs (denoted as FA NPs) trigger the detachment of amyloid-like fibers that connect to the peptidoglycan, reduce the number of polysaccharides and proteins in extracellular polymeric substances damaging its stability and resulting in the disassembly of the biofilm. FA NPs enhance the killing efficacy of encapsulated sitafloxacin sesquihydrate (Sita) by facilitating the penetration within the biofilm, achieving complete elimination of Staphylococcal biofilm in mice.

A prototrophic suppressor of a Vibrio fischeri D-glutamate auxotroph reveals a member of the periplasmic broad-spectrum racemase family (BsrF)

Coppinger MN, Laramore K, Popham DL, Stabb EV

J Bacteriol. 2024 206(3):e0033323. doi: 10.1128/jb.00333-23

This study explored the constraints on PG evolution by blocking essential steps in its biosynthesis in Vibrio fischeri and then selecting mutants with restored prototrophy. A single suppressor was isolated on LBS supplemented with iso-D-Gln: this suppressor has a genomic amplification formed by the creation of a novel junction that fuses proB to a gene encoding a putative broad-spectrum racemase, bsrF. An engineered bsrF allele lacking the putative secretion signal (ΔSS-bsrF) also suppressed D-Glu auxotrophy, resulting in PG that was indistinguishable from the wild type.


Characterizing the D-Amino Acid Position in Peptide Epimers by Using Higher-Energy Collisional Dissociation Tandem Mass Spectrometry: A Case Study of Liraglutide

Chen Y.-C., Wu H.-Y., Lin L.-C., Chang C.-W., Liao P.-C.

International Journal of Molecular Sciences 2024, 25(3), art. no. 1379. DOI: 10.3390/ijms25031379

D-amino acid-containing peptides (DAACPs) occur in biological and artificial environments and for their investigation various mass spectrometry-based analytical approaches have been developed although the capability of higher-energy collisional dissociation (HCD) fragmentation to characterize DAACP sites has not been evaluated. Here, the normalized spectra intensity under different conditions of HCD were compared, using liraglutide along with its DAACPs. The difference in the intensity of y ions between DAACPs and all-L liraglutide could not only distinguish them but also localize the sites of D-amino acids in the DAACPs.

Second generation Al(18)F-labeled D-amino acid peptide for CXCR4 targeted molecular imaging

Spahn MA, Luyten K, Van Loy T, Sathekge M, Deroose CM, Koole M, Schols D, Vanduffel W, De Vos K, Annaert P, Bormans G, Cleeren F

Nucl Med Biol. 2024 132-133:108906. doi: 10.1016/j.nucmedbio.2024.108906

This study aimed to develop and assess a second generation Al18F-labeled D-amino acid peptide based on the viral macrophage inflammatory protein II for CXCR4 targeted molecular imaging. The lead ligand AlF-NOTA-2xDV1(c11sc12s) showed six-fold higher affinity for human CXCR4 compared to Ga-Pentixafor. The corresponding radiotracer was obtained in a good radiochemical yield and apparent molar activity. The authors reported that [18F]AlF-NOTA-2xDV1(c11sc12s) is not specific for CXCR4 and is also a substrate for OATP1B1 and/or OATP1B3, known to mediate hepatic uptake.

68 Ga-Labeled TMTP1 Modified with D-Amino Acid for Positron Emission Tomography Diagnosis of Highly Metastatic Hepatocellular Carcinoma

Wang Y, Sun Y, Zeng X, Zhuang R, Huang J, Zhang X, Guo Z, Li Y

J Med Chem. 2024 67(3):2165-2175. doi: 10.1021/acs.jmedchem.3c02090

TMTP1 (NVVRQ) has been proven to selectively target various highly metastatic tumor cells. To optimize its used, here eight peptide probes were produced, employing innovative chemical modification strategies involving D-amino acid modification and retro-inverso isomerization. Notably, [68Ga]TV2 exhibited impressive performance while maintaining a high target-to-nontarget ratio.

Anti-DNA antibody-targeted D-peptide nanoparticles ameliorate lupus nephritis in MRL/lpr mice

Wang Y, Wang S, Liu W, Gu H, Luo M, Xiao T, Zhou M, Ran Y, Xiao S, Xia Y, Wang H

J Autoimmun. 2024 145:103205. doi: 10.1016/j.jaut.2024.103205

Peptide ALW (ALWPPNLHAWVP) targeting anti-dsDNA antibodies has shown promising therapeutic effects in alleviating lupus nephritis, but is potentially limited by poor stability and non-kidney targeting. A D-form modified ALW, called D-ALW, was produced that was further modified using PEG-PLGA nanoparticles to enhance kidney-targeting ability and extend half-life. The D-ALW maintains higher binding and inhibition efficiencies and achieves higher stability: D-ALW nanoparticles exhibit excellent kidney-targeting ability and prolong the half-life of the peptides in BALB/c mice and significantly reduce the glomerular deposition of IgG and C3, improve renal histopathologies, and markedly prolong lifespan in MRL/lpr lupus-prone mice.

Engineering Enhanced Antimicrobial Properties in α-Conotoxin RgIA through D-Type Amino Acid Substitution and Incorporation of Lysine and Leucine Residues

Wang M, Liao Z, Zhangsun D, Wu Y, Luo S

Molecules. 2024 29(5):1181. doi: 10.3390/molecules29051181

Antimicrobial peptides (AMPs), host defense peptides, constitute a category of predominant cationic peptides present in diverse life forms. This study focused on the antibacterial activity of α-conotoxin RgIA, and to enhance its stability and efficacy by incorporation of D-amino acids: nine RgIA mutant analogs were produced and several of them showed inhibitory efficacy against various pathogenic bacteria and fungi. These polypeptides achieved antibacterial effects through the disruption of bacterial cell membranes. Mutants with antibacterial activity exhibited lower hemolytic activity and cytotoxicity, with Pep 8 demonstrating favorable safety in mice. RgIA mutants incorporating D-amino acids exhibited notable stability and adaptability, sustaining antibacterial properties across diverse environmental conditions.

Retro-Inverso Collagen Modulator Peptide Derived from Serpin A1 with Enhanced Stability and Activity In Vitro

Errante F, Pallecchi M, Bartolucci G, Frediani E, Margheri F, Giovannelli L, Papini AM, Rovero P J Med Chem. 2024 Mar 12. doi: 10.1021/acs.jmedchem.4c00137. Online ahead of print. Based on the collagen turnover modulation properties of SA1-III, a decapeptide derived from a serine protease inhibitor (serpin A1), this work investigated shorter, second-generation peptides: a tetrapeptide candidate was further modified employing the retro-inverso approach that uses D-amino acids. The modified peptide AAT11RI displayed notably high activity in vitro, showing a mode of action based on the inhibition of collagen degradation, stability against dermal enzymes.

Mirror-Image Phage Display for the Selection of D-Amino Acid Peptide Ligands as Potential Therapeutics

Malhis M, Funke SA

Curr Protoc. 2024 Feb;4(2):e957. doi: 10.1002/cpz1.957

In this work, using mirror-image phage display with a randomized 12-mer peptide library, D-amino acid peptides which bind to the Tau protein and modulate its aggregation in vitro, were identified. To perform mirror-image phage display, the target protein needs to be synthesized as D-amino acid version. If the target protein sequence is too long to be synthesized properly, smaller peptides derived from the full-length protein can be used for the selection process. Here, a protocol for mirror-image phage display selection on the PHF6* peptide of Tau, based on the commercially available Ph.D.™-12 Phage Display Peptide Library Kit, leading to D-peptides that also bind the full-length Tau protein (Tau441), next to PHF6*, was provided, as well as protocols for the first characterization of those D-peptides.

Multiplatform High-Definition Ion Mobility Separations of the Largest Epimeric Peptides

Thurman HA, Wijegunawardena G, Berthias F, Williamson DL, Wu H, Nagy G, Jensen ON, Shvartsburg AA

Anal Chem. 2024 96(6):2318-2326. doi: 10.1021/acs.analchem.3c03079

Ion mobility spectrometry (IMS) coupled to mass spectrometry (MS) is a versatile tool to fractionate complex mixtures, distinguish structural isomers, and elucidate molecular geometries. Concerning D-amino acid-containing peptides (DAACPs), both linear IMS and FAIMS previously disentangled D/L epimers with up to ∼30 residues. Here, the authors demonstrate baseline resolution of the largest known D/L peptides (CHH from Homarus americanus, 72 residues) with a dynamic range up to 100.

Mechanism of Protease Resistance of D-Amino Acid Residue Containing Cationic Antimicrobial Heptapeptides

Sarkar T, Ghosh S, Sundaravadivelu PK, Pandit G, Debnath S, Thummer RP, Satpati P, Chatterjee S

ACS Infect Dis. 2024 10(2):562-581. doi: 10.1021/acsinfecdis.3c00491

This work developed all-D-amino acid containing small cationic peptides P4C and P5C, which are completely protease-resistant, noncytotoxic, nonhemolytic, and potent against the ESKAPE pathogens in comparison to their L analogues. The poor binding affinity between D-peptides and the protease, resulting in the inactive complex formation, explained their experimentally observed proteolytic stability.

Synthesis and anticancer evaluation of [D-Ala]-nocardiotide A

Maharani R, Muhajir MI, Dirgantara JM, Hardianto A, Mayanti T, Harneti D, Nurlelasari, Farabi K, Hidayat AT, Supratman U, Siahaan A

RSC Adv. 2024 14(6):4097-4104. doi: 10.1039/d4ra00025k. Erratum in RSC Adv. 2024 Mar 4;14(11):7571.

Anticancer peptides (ACPs) with high selectivity and high cell penetration ability are a promising candidate, as well as they are easy to modify. A cyclohexapeptide called nocardiotide A was isolated from the marine sponge Callyspongia sp., which is cytotoxic towards several cancer cells such as MM, 1S, HeLa, and CT26 cells. Here, [D-Ala]-nocardiotide A was produced using a combination of solid phase peptide synthesis (SPPS) and liquid phase peptide synthesis (LPPS). The anticancer activity of the peptide was determined against HeLa cancer cell lines with an IC50 value of 52 μM.


A magnetically embedded pump-free LoC-SERS device based on enzyme-mediated cascade reaction for gastric cancer-related D-amino acids detection

Shen K., Zhang D., Yin H., Lu B., Hua Z., Tan M., Qian Y.

Sensors and Actuators B: Chemical 2024, 409, art. no. 135615, DOI: 10.1016/j.snb.2024.135615

A surface-enhanced Raman scattering (SERS) pump-free microfluidic chip (LoC-SERS) based on a D-amino acid oxidase (DAAO)-mediated cascade reaction was produced for the rapid quantitative evaluation of D-proline and D-alanine associated with gastric cancer (GC). With this device, D-Pro and D-Ala in saliva were rapidly and accurately quantified with the limit of detection down to the μM. Moreover, with capillary drive technology, the analysis process was automatically integrated making it highly simple and portable.

Enantiomer-Specific Colorimetric Tandem Assays for Salivary D-Alanine Associated with Gastric Cancer

Liu C., Wu Y., Li M., Liu F., Kong P., Yang H., Liu X.

Analytical Chemistry 2024, 96 (5), 1906-1912, DOI: 10.1021/acs.analchem.3c04017

An enantiomer-specific tandem assay of D-Ala based on the colorimetric reaction between 2,4-dinitrophenylhydrazine and pyruvic acid generated from the deamination of D-Ala by D-amino acid oxidase was set up. A linear concentration range is established from 20 to 400 μmol/L with a limit of detection of 1.01 μmol/L. Real saliva sample tests reveal that the levels of D-Ala in gastric cancer cases are remarkably higher than those in healthy individuals. The concentration of D-Pro and the proportion of D-Ala could be calculated providing further molecule- and individual-specific information.


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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