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D-Lysine is the unnatural isomer of L-Lysine that has the ability to reduce non-enzymatic glycation in vitro. D-Lysine also exists as polypeptide chains of poly-D-lysine, a nonspecific adhesion-promoting molecule that has the potential to be a polymeric drug carrier.

D-Amino Acids
Catalog number
CAS number
Molecular Formula
Molecular Weight
(2R)-2,6-diaminohexanoic acid
D-2,6-Diaminohexanoic acid; (R)-2,6-Diaminocaproic acid; (2R)-2,6-diaminohexanoic acid; H-D-Lys-OH; D-Lys; H D Lys OH
White or light yellow powder
≥ 99.5% (Chiral HPLC)
1.125±0.06 g/cm3 (Predicted)
Melting Point
218 °C (dec.)
Boiling Point
311.5±32.0 °C (Predicted)
Store at 2-8 °C
InChI Key
Canonical SMILES
1. Elucidation of the d-lysine biosynthetic pathway in the hyperthermophile Thermotoga maritima
Tetsuya Miyamoto, Masumi Katane, Yasuaki Saitoh, Masae Sekine, Hiroshi Homma FEBS J. 2019 Feb;286(3):601-614. doi: 10.1111/febs.14720. Epub 2018 Dec 28.
Various d-amino acids are involved in peptidoglycan and biofilm metabolism in bacteria, suggesting that these compounds are necessary for successful adaptation to environmental changes. In addition to the conventional d-alanine (d-Ala) and d-glutamate, the peptidoglycan of the hyperthermophilic bacterium Thermotoga maritima contains both l-lysine (l-Lys) and d-Lys, but not meso-diaminopimelate (meso-Dpm). d-Lys is an uncommon component of peptidoglycan, and its biosynthetic pathway remains unclear. In this study, we identified and characterized a novel Lys racemase (TM1597) and Dpm epimerase (TM1522) associated with the d-Lys biosynthetic pathway in T. maritima. The Lys racemase had a dimeric structure containing pyridoxal 5'-phosphate as a cofactor. Among the amino acids, it exhibited the highest racemase activity toward d- and l-Lys, and also had relatively high activity toward d- and l-enantiomers of ornithine and Ala. The Dpm epimerase had the highest epimerization activity toward ll- and meso-Dpm, and also measurably racemized certain amino acids, including Lys. These results suggest that Lys racemase contributes to production of d-Lys and d-Ala for use as peptidoglycan components, and that Dpm epimerase converts ll-Dpm to meso-Dpm, a precursor in the l-Lys biosynthetic pathway.
2. Poly-d-lysine coated nanoparticles to identify pro-inflammatory macrophages
Derek S Hernandez, Hattie C Schunk, Karan M Shankar, Adrianne M Rosales, Laura J Suggs Nanoscale Adv. 2020 Jul 13;2(9):3849-3857. doi: 10.1039/d0na00373e. eCollection 2020 Sep 16.
Identifying pro-inflammatory macrophages (M1) is of immense importance to diagnose, monitor, and treat various pathologies. In addition, adoptive cell therapies, where harvested cells are isolated, modified to express an M1-like phenotype, then re-implanted to the patient, are also becoming more prevalent to treat diseases such as cancer. In a step toward identifying, labeling, and monitoring macrophage phenotype for adoptive cell therapies, we developed a reactive oxygen species (ROS)-sensitive, gold nanoparticle (AuNP) that fluorescently labels M1 macrophages. AuNPs are electrostatically coated with a proteolysis resistant, fluorescein isothiocyanate-conjugated, poly-d-lysine (PDL-FITC) that is susceptible to backbone cleavage by ROS. When PDL-FITC is bound to AuNPs, fluorescence is quenched via a combination of nanoparticle surface (NSET) and Forster resonance (FRET) energy transfer mechanisms. Upon ROS-induced cleavage of PDL-FITC, up to a 7-fold change in fluorescence is demonstrated. PDL-FITC AuNPs were loaded into RAW 264.7 macrophages (RAWs) and primary bone marrow- derived macrophages (BMDMs) prior to in vitro polarization. For both cell types, detectable differences in intracellular fluorescence were observed between M1 polarized and non-stimulated (M0) control groups after 24 h using both confocal imaging and flow cytometry. PDL-FITC AuNPs can potentially be useful in identifying M1 macrophages within diverse cell populations and provide longitudinal macrophage response data to external cues.
3. The Y430F mutant of Salmonella d-ornithine/d-lysine decarboxylase has altered stereospecificity and a putrescine allosteric activation site
Robert S Phillips, Kim-Ngoc Nguyen Hoang Arch Biochem Biophys. 2022 Nov 30;731:109429. doi: 10.1016/j.abb.2022.109429. Epub 2022 Oct 18.
Tyrosine-430 of d-ornithine/d-lysine decarboxylase (DOKDC) is located in the active site, and was suggested to be responsible for the D-stereospecificity of the enzyme. We have prepared the Y430F mutant form of Salmonella enterica serovar typhimurium DOKDC and evaluated its catalytic activity with D- and l-lysine and ornithine. The kinetic results show that the Y430F mutant has measurable decarboxylase activity with both D- and l-lysine and ornithine, which wild type DOKDC does not. Spectroscopic experiments show that these amino acids bind to form external aldimine complexes with the pyridoxal-5'-phosphate with λmax = 425 nm. In addition, we have obtained crystal structures of Y430F DOKDC bound to HEPES, putrescine, d-ornithine, d-lysine, and d-arginine. The d-amino acids bind in the crystals to form equilibrium mixtures of gem-diamine and external aldimine complexes. Furthermore, the crystal structures reveal an unexpected allosteric product activator site for putrescine located on the 2-fold axis between the two active sites. Putrescine binds by donating hydrogen bonds from the ammonium groups to Asp-361 and Gln-358 in the specificity helix of both chains. Addition of 0.1-1 mM putrescine eliminates the lag in steady state kinetics and abolishes the sigmoid kinetics. The catalytic loop was modeled with AlphaFold2, and the model shows that Glu-181 can form additional hydrogen bonds with the bound putrescine, likely stabilizing the catalytic closed conformation.
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