$1033.00 - $3101.00
Ac-L-Lys-OH is Nalpha-acetyl-L-lysine. The alpha-amino group is capped as an acetamide, while the lysine epsilon-amino side chain remains free and the carboxyl group is unprotected.
This protection state gives a very different synthetic role from Fmoc-Lys(Boc)-OH. Nalpha acetylation is already part of the structure, while the exposed epsilon amine can participate in acylation, labeling or other side-chain chemistry.
Product Information
| Product Name | Ac-L-Lys-OH |
| Catalog No. | AS4103 |
| CAS No. | 1946-82-3 |
| Molecular Formula | C8H16N2O3 |
| Molecular Weight | 188.23 g/mol |
| Chemical Identity | Nalpha-acetyl-L-lysine |
| Building Block Type | N-alpha-acetylated lysine derivative with free epsilon amine |
| Primary Applications | Lysine side-chain derivatization, N-acetyllysine research and analytical/biochemical standards |
The Free Epsilon Amine Is the Main Reactive Handle
The lysine side-chain amine can react with activated carboxylates, NHS esters, labels and other amine-selective reagents. If the experimental goal is to compare N-terminal versus lysine-side-chain labeling, the same site-selectivity principles described in our fluorescent labeling guide apply to the final construct.
N-Alpha Acetylation Limits Normal Chain Extension
The alpha amino group is an acetamide and is therefore not a normal nucleophile for peptide elongation. Ac-L-Lys-OH should not be purchased as though “Ac” were a conveniently removable N-protecting group. We consider it most useful when the Nalpha-acetyl state itself is required or when chemistry is intentionally directed through the free epsilon amine.
Compare with Ac-Lys(Z)-OH
In Ac-Lys(Z)-OH the same Nalpha-acetyl motif is retained but the epsilon amine is Cbz-protected. That product is preferable when the side-chain nitrogen must remain silent during other transformations; Ac-L-Lys-OH is preferable when the epsilon amine is the desired reaction site.
Procurement and QC Considerations
Confirm CAS 1946-82-3, C8H16N2O3, MW 188.23 g/mol and L stereochemistry. Public safety records classify Nalpha-acetyl-L-lysine as harmful if swallowed and as a skin, eye and respiratory irritant. For analytical applications, water content and assay can matter because this is a small, polar amino-acid derivative.
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
Which amino group is acetylated in Ac-L-Lys-OH?
The alpha-amino group is acetylated; the lysine epsilon-amino side chain remains free.
Can the free epsilon amine be derivatized?
Yes. It is the principal amine handle for side-chain acylation or labeling.
Is Ac-L-Lys-OH a standard protected lysine for SPPS?
No. Nalpha acetylation is a stable structural modification rather than a routine temporary Fmoc/Boc-type protection.
Related Technical Resources
Compare Ac-Lys(Z)-OH when epsilon-amino protection is required.
Explore custom N-acetylated and lysine-modified peptide synthesis.