H-D-Gln-NH2 · HCl

H-D-Gln-NH2 · HCl is a hydrochloride salt of an amino acid derivative corresponding to D-glutamine in a protected-free, amide-bearing form, with a side chain containing a primary amide that can participate in hydrogen bonding and nucleophilic acyl-transfer chemistry under appropriate conditions. The molecule presents an alpha-amino functionality and a C-terminal primary amide (NH2) motif, while the D stereochemistry at the chiral center supports stereochemically defined incorporation into peptide and peptidomimetic frameworks. As the HCl salt, the basic amino groups are protonated, which can improve handling and solubility for coupling and analytical workflows while requiring controlled base selection for deprotonation during peptide bond formation. The combination of an unprotected amine and a side-chain amide makes the compound a practical chiral building block for preparing glutamine-containing sequences and for downstream derivatization into protected intermediates, labeled standards, and structure-defined biochemical probes.

1. Peptide Synthesis

H-D-Gln-NH2 · HCl supports peptide coupling chemistry for building D-glutamine-containing peptides and peptidomimetics in research-grade synthesis. The alpha-amino group and the side-chain primary amide enable formation of amide linkages and provide strong hydrogen-bonding patterns that influence conformational preferences in peptide scaffolds. Protonation as the hydrochloride salt can be managed through base selection to enable efficient coupling while maintaining stereochemical integrity of the D center. Downstream workflows often convert the free amine into N-protected glutamine derivatives or incorporate the residue directly into peptide assembly strategies to generate stereochemically defined analog libraries for mechanistic and structure-activity relationship studies.

2. Chemical Biology Probes

H-D-Gln-NH2 · HCl can be applied in chemical biology research where glutamine-like side-chain recognition and amide-mediated interactions are used to probe binding sites and substrate preferences. The side-chain primary amide provides a handle for hydrogen-bond donor/acceptor interactions that can be exploited in molecular recognition studies and in designing amino acid-based probes for enzyme or receptor assays. D stereochemistry can be leveraged to tune resistance to proteolysis and to distinguish stereospecific binding modes when incorporated into peptide tags or small-molecule conjugates. The hydrochloride salt form facilitates preparation of defined conjugation intermediates and analytical standards that reflect the stereochemical identity of the residue.

3. Protected Amino Acid Chemistry

H-D-Gln-NH2 · HCl serves as a chiral precursor for preparing N-protected amino acid derivatives and C-terminally modified glutamine building blocks used in protected amino acid synthesis. The presence of both an alpha-amino group and a side-chain amide allows orthogonal protection planning, where N-protection strategies can be selected to control peptide coupling selectivity while preserving the side-chain functionality for later transformations. Deprotonation and selective protection can generate intermediates compatible with standard peptide coupling reagents and with solid-phase or solution-phase assembly approaches. The resulting protected forms can be used to prepare D-glutamine-containing fragments for combinatorial chemistry, SAR studies, and stereochemically controlled peptide analog construction.

4. Bioconjugation Chemistry

H-D-Gln-NH2 · HCl can be utilized for bioconjugation workflows that require glutamine-like amide functionality for stable linker design and for generating defined biomolecule conjugates. The side-chain primary amide can participate in coupling to activated carboxylates or can be transformed into derivatives that support attachment to proteins, peptides, or polymer backbones while maintaining a stereochemically defined D residue. Hydrochloride salt handling supports reproducible preparation of conjugation-ready solutions, and subsequent derivatization can introduce handles for downstream labeling or purification strategies. Bioconjugation applications may include stereodefined peptide tags, affinity probes, and analytical reagents where the amide-rich environment improves interaction specificity and stability of the conjugate.

5. Analytical Standards And Labeling

H-D-Gln-NH2 · HCl is suitable for analytical research as a stereochemically defined amino acid standard and as a starting material for isotopic or derivatization-based quantification methods. The D configuration at the alpha carbon enables discrimination from L-glutamine in chiral chromatographic workflows and in method validation for amino acid profiling. The side-chain primary amide supports derivatization routes that can generate detectable derivatives for LC-MS or chromatographic assays, while the hydrochloride salt form assists consistent sample preparation. Downstream labeling and derivatization from this chiral intermediate support method development for peptide hydrolysate analysis, stereochemical integrity checks, and quality control of glutamine-containing synthetic products.

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