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Dansyl-L-Leu-OH is the dansyl sulfonamide derivative of L-leucine. It combines the environment-sensitive dimethylaminonaphthalene fluorophore with the hydrophobic isobutyl side chain of leucine and retains a free carboxyl group.
The reagent is best treated as a fluorescent amino-acid derivative rather than a standard peptide monomer. Its dansylated amino group is already chemically committed, so direct substitution for Fmoc-Leu-OH in routine SPPS would change both reactivity and the intended molecular structure.
Product Information
| Product Name | Dansyl-L-Leu-OH |
| Catalog No. | AS4099 |
| CAS No. | 1100-22-7 |
| Molecular Formula | C18H24N2O4S |
| Molecular Weight | 364.46 g/mol |
| Chemical Identity | N-dansyl-L-leucine |
| Building Block Type | Fluorescent dansylated amino-acid derivative |
| Primary Applications | Fluorescence research, amino-acid probe studies and analytical chemistry |
What the Leucine Side Chain Adds
Leucine contributes a hydrophobic, branched side chain to the fluorescent scaffold. That changes partitioning and noncovalent interactions compared with more polar dansylated amino acids. We consider the amino-acid portion of a dansyl probe part of its binding chemistry, not an inert carrier for the fluorophore.
When to Use a Pre-Dansylated Amino Acid
A pre-dansylated amino acid is convenient when the fluorescent compound itself is the analytical probe. When a fluorophore must instead be positioned at the N-terminus or a lysine side chain of a longer peptide, the chemistry and interpretation are different; see our fluorescent peptide labeling site-selection guide.
Compare with Dansyl-L-Proline
Dansyl-L-proline is a closely related fluorescent probe with a cyclic proline scaffold and a well-established role as a human serum albumin site-II marker. Dansyl-L-Leu-OH should not automatically be assigned that same site specificity simply because it contains the same dansyl fluorophore.
Procurement and QC Considerations
Confirm CAS 1100-22-7, C18H24N2O4S, MW 364.46 g/mol and L-leucine stereochemistry. For fluorescence measurements, verify chromatographic purity and protect solutions from conditions that can alter fluorophore response. Public supplier safety information classifies the material as harmful if swallowed and as a skin, eye and respiratory irritant.
Product Documents
A Safety Data Sheet (SDS / 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
Is Dansyl-L-Leu-OH a fluorescent compound?
Yes. The dansyl group provides fluorescence that is sensitive to the local chemical environment.
Can it replace Fmoc-Leu-OH in standard SPPS?
No. Its amino group is already dansyl-sulfonylated rather than temporarily Fmoc-protected.
How does it differ from Dansyl-L-proline?
The dansyl fluorophore is shared, but the amino-acid scaffold is different; this can change binding, hydrophobicity and analytical behavior.
Related Technical Resources
Compare Dansyl-L-proline and its albumin-binding probe use.
Discuss synthesis of a fluorescently labeled peptide.