H-Thr(Ac)-OH · HCl

H-Thr(Ac)-OH · HCl is a threonine-derived amino acid hydrochloride in which the side-chain hydroxyl is acetylated (Thr(Ac)), while the amino group remains in the free N-terminal form (H-threonine acetylated side chain). The molecule therefore presents a chiral α-carbon typical of amino acid chemistry, a carboxylic acid for C-terminal activation, and an acetyl-protected alcohol that modulates hydrogen-bonding and reactivity during peptide coupling. The hydrochloride salt form increases handling stability and can influence solubility and salt-mediated activation behavior in synthetic workflows. The acetylated side-chain provides a chemically robust protection strategy that can be removed under conditions compatible with peptide synthesis, enabling downstream conversion to the native threonine side chain or to further side-chain functionalization.

1. Protected Amino Acids

H-Thr(Ac)-OH · HCl is used in protected amino acid synthesis workflows where the acetylated threonine side-chain hydroxyl serves as an alcohol-protecting group during peptide building block preparation. The free carboxylic acid and N-terminus enable conversion to coupling-ready derivatives while the O-acetyl group suppresses undesired side reactions such as acylation or cross-linking involving the side-chain hydroxyl. Salt formation with HCl supports reproducible handling in fine chemical synthesis and can be leveraged for controlled formation of activated intermediates. The resulting protected amino acid intermediate can be carried forward into peptide assembly and later deprotected to regenerate the native threonine functionality for structure-function studies.

2. Peptide Synthesis

H-Thr(Ac)-OH · HCl functions as a threonine-based peptide coupling component for assembling peptide sequences that require orthogonal protection of the side-chain hydroxyl. The acetyl group on the threonine side chain provides a temporary protection layer that is compatible with common peptide coupling strategies focused on activating the C-terminal carboxyl group and maintaining side-chain integrity. The chiral center ensures stereochemical fidelity of the incorporated threonine residue, supporting the construction of diastereomerically controlled peptide analogs. After peptide assembly, side-chain deprotection can enable access to threonine hydroxyl for subsequent derivatization, cyclization, or biochemical mimicry in peptide science.

3. Chemical Biology Labeling

H-Thr(Ac)-OH · HCl can be applied in chemical biology research to generate threonine-containing probes and labeling handles where controlled unveiling of the side-chain hydroxyl is required. The acetyl-protected hydroxyl reduces premature reactivity during conjugation steps, while the amino acid scaffold enables incorporation into peptides or peptidomimetics used as recognition elements. The hydrochloride form can facilitate solubility and reproducible intermediate preparation when preparing conjugation-ready fragments or standards. Downstream deprotection yields a threonine side chain that can participate in further functional group transformations for biomolecule modification and molecular recognition assays.

4. Process Chemistry Intermediate

H-Thr(Ac)-OH · HCl serves as a practical chiral amino acid intermediate in process chemistry intermediate design for manufacturing peptide building blocks and protected amino acid derivatives. The combination of a stable O-acetyl group and an amino acid hydrochloride salt form supports predictable handling and can be integrated into scalable protection/deprotection sequences that minimize side reactions of the hydroxyl group. The carboxylic acid functionality enables conversion to activated forms for downstream coupling, while the stereocenter maintains the integrity of threonine incorporation in larger synthetic routes. The compound can therefore be employed in industrially relevant synthesis planning for specialty chemical production where protected amino acid consistency and downstream deprotection compatibility are central.

5. Peptidomimetics And SAR Studies

H-Thr(Ac)-OH · HCl supports peptidomimetic construction and structure-activity relationship studies by enabling threonine residue incorporation with protected side-chain hydroxyl chemistry. The acetylated side chain can be carried through scaffold assembly to control polarity and hydrogen-bonding patterns during analog generation, while later deprotection or further derivatization allows systematic variation of side-chain properties. The stereodefined threonine backbone contributes to maintaining conformational and interaction features relevant to SAR investigations. The resulting threonine-containing analogs can be used as chemical probes or fragment-like components in medicinal chemistry programs focused on mapping structure-function relationships.

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