Fmoc-Tyr(SO3H)-OH

Fmoc-Tyr(SO3H)-OH is a fluorenylmethoxycarbonyl (Fmoc) protected tyrosine derivative bearing a sulfonic acid group on the phenolic side chain, yielding a strongly polar, anionic functionality while retaining the canonical amino acid backbone for peptide chemistry. The molecule contains an Fmoc carbamate for N-protection, a free carboxylic acid for C-terminal coupling, and a sulfonate-bearing aromatic ring that can participate in ionic interactions and can be chemically transformed under controlled conditions. The chiral center at the amino acid alpha-carbon provides stereochemical fidelity for incorporation into peptide sequences, while the sulfonic acid enables predictable acid-base behavior and salt formation that influences solubility and purification. As a protected amino acid building block, Fmoc-Tyr(SO3H)-OH functions as a research-grade intermediate for constructing sulfonated tyrosine motifs relevant to post-translational modification mimicry and polar side-chain engineering.

1. Peptide Synthesis

Fmoc-Tyr(SO3H)-OH is used in solid-phase peptide synthesis as an Fmoc-protected amino acid building block for introducing sulfonated tyrosine residues into peptide chains. The Fmoc carbamate supports standard base-mediated deprotection, while the free carboxylic acid enables peptide coupling to growing C-termini using common amide-forming chemistries. The SO3H substituent on the aromatic ring provides a charged side chain that can be carried through synthesis with careful control of conditions that might otherwise affect sulfonate stability. Downstream peptide products include sulfated-tyrosine mimics for probing sequence-dependent electrostatics, receptor binding motifs, and recognition elements in peptide-based molecular scaffolds.

2. Chemical Biology

Fmoc-Tyr(SO3H)-OH is applied in chemical biology workflows that model or perturb tyrosine sulfation-like features in protein interaction studies. The protected amino acid format allows site-specific incorporation of the sulfonated aromatic side chain into peptides used as probes, mimetics, or competitive ligands. The sulfonic acid group can support ionic and hydrogen-bonding interactions, enabling structure-function interrogation of how charged post-translational modification patterns influence binding selectivity. Synthesized sulfonated peptides can be employed for mapping interaction surfaces, validating motif hypotheses, and generating chemically defined reagents for biochemical assays.

3. Bioconjugation Chemistry

Fmoc-Tyr(SO3H)-OH is suitable for bioconjugation-oriented intermediate preparation where a sulfonated tyrosine residue is required as a polar handle within larger conjugates. The amino acid backbone supports incorporation into peptide linkers that can later be conjugated to proteins, nanoparticles, or targeting scaffolds through orthogonal functional groups present elsewhere in the construct. The SO3H functionality can be retained to modulate overall charge, improve aqueous compatibility, and influence conjugate behavior during purification and downstream processing. Resulting conjugation-ready peptides and peptidomimetic linkers can be used to generate defined molecular assemblies for biochemical research and applied materials development.

4. Peptidomimetics And SAR

Fmoc-Tyr(SO3H)-OH is utilized in peptidomimetic construction and structure-activity relationship (SAR) studies where a sulfonated aromatic side chain is used to tune binding electrostatics and conformational preferences. The Fmoc-protected N-terminus and carboxylic acid support systematic analog synthesis by varying chain length, neighboring residues, or protecting-group patterns while maintaining the sulfonated tyrosine pharmacophore. The charged SO3H group can be leveraged to evaluate how ionic strength and local charge density affect activity trends in receptor or enzyme recognition models. Generated analog series can serve as chemically defined inputs for SAR mapping and for refining fragment-based or motif-based molecular design strategies.

5. Process Chemistry Intermediate

Fmoc-Tyr(SO3H)-OH is relevant to process chemistry intermediate preparation for manufacturing sulfonated tyrosine-containing peptides and peptide fragments at scale. The Fmoc protection provides a robust, controllable N-protection strategy during peptide assembly, while the sulfonic acid substituent supports predictable salt-state behavior that can be managed during workup and purification. The molecule's stable amino acid architecture enables reproducible coupling-to-deprotection cycles in peptide manufacturing settings where consistent building-block performance is required. Downstream, the compound can be incorporated into larger manufacturing routes for producing sulfonated peptide standards, reference materials, and industrially produced peptide intermediates used in research and specialty chemical production.

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