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Fmoc-Val-Val-OH is a preassembled, N-terminally Fmoc-protected L-Val-L-Val dipeptide with a free C-terminal carboxylic acid. PubChem identifies the structure as the (2S,2S) L-Val-L-Val stereoisomer, providing a defined Val-Val sequence fragment for peptide synthesis.
The Val-Val motif contains two consecutive beta-branched residues. This combination is hydrophobic and sterically demanding, making the product particularly relevant when a chemist wants to introduce a defined Val-Val junction without rebuilding both residues individually during SPPS.
Product Information
| Product Name | Fmoc-Val-Val-OH |
| Catalog No. | AS4072 |
| CAS No. | 116460-32-3 |
| Molecular Formula | C25H30N2O5 |
| Molecular Weight | 438.52 g/mol |
| Sequence | L-Val-L-Val (VV) |
| Stereochemistry | (2S,2S) for the two valine alpha centers |
| Primary Use | Preassembled hydrophobic dipeptide fragment for peptide synthesis |
Why Val-Val Can Be a Difficult SPPS Junction
Valine is beta-branched, which increases steric congestion around the reacting amino and carboxyl groups. Two consecutive valines can therefore create a more demanding coupling environment than less hindered residues such as glycine or alanine.
In addition, hydrophobic sequences can promote resin-bound peptide aggregation. A preassembled Val-Val fragment removes one Val-Val coupling event from the downstream route, although coupling of the fragment itself can still require optimization.
Fmoc-Val-Val-OH vs Fmoc-Val-Ala-OH
Fmoc-Val-Ala-OH contains one beta-branched Val followed by the smaller Ala residue. Fmoc-Val-Val-OH contains two beta-branched hydrophobic residues and therefore represents a different steric and conformational motif.
The two dipeptides are not interchangeable simply because they share an N-terminal valine; sequence identity must match the target peptide exactly.
Application Scope
Applications include peptide fragment coupling, synthesis of hydrophobic peptide motifs, peptidomimetic SAR, preparation of constrained or membrane-associated peptide sequences and routes where a preassembled Val-Val junction improves step economy.
Final peptides may be evaluated in binding, enzyme, membrane, cell-based or in vivo studies depending on the target sequence. The protected dipeptide itself is an upstream synthetic intermediate.
Purchasing and QC Considerations
Confirm CAS 116460-32-3, the exact L-Val-L-Val sequence and stereochemistry, Fmoc protection and lot-specific purity. Molecular formula and nominal mass alone do not replace stereochemical identity confirmation.
Product Documents
A Material Safety Data Sheet (MSDS) is available for this product to support laboratory handling, storage and safety assessment.
Certificates of Analysis (COAs) are batch-specific. Please contact us to request the COA for your product, and we will provide it by email.
Frequently Asked Questions
Why use a preassembled Val-Val dipeptide?
It fixes the L-Val-L-Val junction and can eliminate one sterically demanding coupling step from a longer synthesis.
Is Fmoc-Val-Val-OH the same as Fmoc-Val-Ala-OH?
No. The second residue is different, changing molecular identity, steric demand and peptide sequence.
Can Val-Val sequences aggregate during SPPS?
Hydrophobic beta-branched sequences can contribute to aggregation, although the extent depends on the full sequence, resin and solvent system.
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