H-[15N]Leu-OH is a free, isotopically labeled amino acid derivative consisting of leucine bearing an amino group labeled with nitrogen-15, with the side chain characteristic of the proteinogenic aliphatic amino acid class. The molecule contains an α-amino functionality (as the 15N-labeled amino group) and a carboxylic acid (-COOH) that can exist in zwitterionic form in aqueous media, and it retains the standard carbon skeleton of leucine without additional protecting groups or esterification. In research and analytical workflows, the labeled leucine is used as an isotopic tracer for amino acid metabolism studies, protein or peptide labeling experiments, and NMR or mass spectrometry method development where incorporation or detection of the 15N label is required.
CAT No: CP27256
CAS No:59935-31-8
Synonyms/Alias:L-Valine-15N;59935-29-4;H-[15N]VAL-OH;490172_ALDRICH
H-[15N]Leu-OH is a uniformly nitrogen-15 labeled L-leucine amino acid, retaining the canonical α-amino acid framework with a stereogenic center at the Cα position and a hydrophobic isobutyl side chain. The molecule presents a free carboxylic acid and a free primary amino group, enabling salt formation and direct participation in standard amino acid coupling chemistry while maintaining the chiral identity of L-leucine. The [15N] label on the amino nitrogen provides an NMR-active, isotopically distinct handle that can be tracked in peptide and protein contexts. As an amino acid building block and isotopic tracer, H-[15N]Leu-OH functions as a chemically defined intermediate for downstream incorporation into labeled peptides, labeled biomolecules, and analytical standards.
1. Peptide NMR Labeling
H-[15N]Leu-OH is applied in structural biochemistry and peptide spectroscopy where site-specific nitrogen-15 enrichment is required for assignment-quality NMR experiments. The labeled α-amino group and preserved L stereochemistry support peptide coupling strategies that install the leucine residue at defined positions within short peptides or larger polypeptide fragments. The isotopic [15N] nucleus enables sensitive monitoring of backbone amide environments after coupling, while the free carboxyl group aligns with common protected amino acid and peptide fragment assembly workflows. Incorporation of this labeled leucine into peptide building blocks supports residue-resolved conformational studies and labeling schemes for mechanistic interpretation in amino acid and peptide chemistry.
2. Protein Engineering Tracing
H-[15N]Leu-OH supports protein engineering and chemical biology workflows that require defined isotopic labeling for studying folding, dynamics, and intermolecular interactions. The compound's L-leucine side chain contributes the hydrophobic, branched aliphatic character typical of leucine in protein cores and binding interfaces, while the [15N] label provides a spectroscopic tag for specific amide sites. The free functional groups allow conversion into activated amino acid forms or protected derivatives compatible with fragment ligation and residue-specific incorporation into engineered sequences. Downstream labeled proteins or protein fragments generated from this amino acid intermediate can be used to map local structural changes and validate residue-level hypotheses in protein structure-function studies.
3. Isotope-Labeled Standards
H-[15N]Leu-OH functions as an analytical research intermediate and isotope-labeled reference material for mass spectrometry and NMR method development. The presence of the carboxylic acid and primary amino group enables controlled derivatization to chromatographically compatible forms, supporting calibration of isotope-resolved detection of leucine-containing analytes. The [15N] label generates a predictable isotopic signature that can be used to distinguish labeled internal standards from unlabeled amino acids and peptide fragments. Use of H-[15N]Leu-OH-derived standards supports quantitative workflows in amino acid metabolism studies, peptide quantitation, and analytical method verification across biochemical research and industrial quality control development.
4. Protected Amino Acid Synthesis
H-[15N]Leu-OH is suitable for preparing N-protected and C-terminally activated leucine derivatives used in protected amino acid synthesis and peptide building block preparation. The free α-amino group can be converted to an N-protected form, while the free carboxylic acid can be transformed into ester or activated acid derivatives, enabling compatibility with peptide coupling chemistries that require controlled reactivity. The L stereocenter is preserved through standard protection and activation sequences, supporting stereochemically consistent incorporation into peptide chains. The resulting protected [15N] leucine intermediates can then be employed for stepwise peptide construction, fragment coupling, and downstream isotopic labeling strategies in research-grade peptide science.
5. Side-Chain Functionalization
H-[15N]Leu-OH can serve as a starting amino acid for side-chain and scaffold functionalization where isotopic labeling must be retained for tracing. The leucine isobutyl side chain provides a hydrophobic handle that can be selectively modified to introduce functional groups for further conjugation or for generating peptidomimetic fragments while keeping the labeled backbone nitrogen available for spectroscopic readout. The free α-functional groups enable orthogonal protection planning so that side-chain transformations can be performed without compromising peptide coupling readiness. Downstream functionalized, [15N]-retaining derivatives can be incorporated into labeled peptides or used as intermediates for chemical biology probes that require isotopic tracking.
6. Fine Chemical Intermediate Preparation
H-[15N]Leu-OH is used in industrial and process chemistry contexts as a defined isotopic amino acid intermediate for manufacturing labeled fine chemicals and research reagents. The compound's simple α-amino acid structure supports scalable conversion into activated forms or protected derivatives used in controlled peptide assembly and isotopic enrichment workflows. The stereochemical integrity of L-leucine and the stable [15N] incorporation enable consistent batch-to-batch labeling outcomes for downstream synthetic manufacturing of labeled peptides, standards, and biochemical research materials. This role aligns with applied amino acid chemistry where isotopically labeled building blocks are required for reproducible analytical performance and traceable synthetic labeling.
If you have any peptide synthesis requirement in mind, please do not hesitate to contact us at . We will endeavor to provide highly satisfying products and services.
Creative Peptides is a trusted CDMO partner specializing in high-quality peptide synthesis, conjugation, and manufacturing under strict cGMP compliance. With advanced technology platforms and a team of experienced scientists, we deliver tailored peptide solutions to support drug discovery, clinical development, and cosmetic innovation worldwide.
From custom peptide synthesis to complex peptide-drug conjugates, we provide flexible, end-to-end services designed to accelerate timelines and ensure regulatory excellence. Our commitment to quality, reliability, and innovation has made us a preferred partner across the pharmaceutical, biotechnology, and personal care industries.
Read More