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Fmoc-HomoArg-OH.HCl is Fmoc-protected L-homoarginine hydrochloride. Homoarginine can be viewed as a guanidinated lysine analog and contains one additional methylene unit between the peptide backbone and guanidino group compared with arginine.
That change in guanidinium spacing can alter charge presentation, side-chain reach, protease recognition, and target interactions in the final peptide. It is therefore useful as a deliberate cationic-residue SAR variable within the broader space of noncanonical amino acids.
Product Information
| Product Name | Fmoc-HomoArg-OH.HCl |
| Catalog No. | AS2022 |
| CAS No. | 208174-14-5 |
| Molecular Formula | C22H27ClN4O4 |
| Molecular Weight | 446.93 g/mol |
| Building Block Type | Fmoc-protected L-homoarginine hydrochloride |
| Primary Applications | Homoarginine-containing peptide synthesis; cationic residue SAR; noncanonical peptide design; guanidinium-spacing studies |
HomoArg Is Not Simply Another Name for Arg
Arginine and homoarginine both contain guanidino functionality, but the side-chain length differs. The extra methylene in homoarginine moves the cationic group farther from the peptide backbone and can change how it interacts with anionic surfaces, receptors, nucleic acids, or protein binding sites.
Why the HCl Salt Must Be Included in Calculations
The listed product is the hydrochloride salt, so formula C22H27ClN4O4 and MW 446.93 g/mol include HCl. Using the free-base molecular weight for reagent equivalents would create a stoichiometric error.
Unprotected Guanidino Functionality Changes Route Planning
Unlike Pbf-protected arginine building blocks, this material is identified as the hydrochloride of Fmoc-homoarginine rather than a side-chain-protected guanidine derivative. The guanidinium state and solubility should therefore be considered during activation, coupling, and purification.
Procurement and QC
Confirm CAS 208174-14-5, formula C22H27ClN4O4, MW 446.93 g/mol, L configuration, Fmoc protection, and hydrochloride salt state. The current Alan H1 uses 'HCI'; the CAS-defined chemical identity is the HCl hydrochloride salt.
Procurement and QC Considerations
For cationic peptide SAR involving Arg/HomoArg substitutions, synthesis feasibility can be evaluated through custom noncanonical peptide synthesis.
Product Documents
A Safety Data Sheet (SDS / MSDS) is available for this product to support laboratory handling, storage and safety assessment.
Frequently Asked Questions
How does homoarginine differ from arginine?
Homoarginine has one additional methylene group before the guanidino functionality.
Does the molecular weight include HCl?
Yes. The listed formula and MW correspond to the hydrochloride salt.
Why use homoarginine in peptide SAR?
It changes the distance and presentation of a guanidinium group without removing its strongly basic character.
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