$344.00 - $1033.00
Z-Lys(Z)-OSu is the N-hydroxysuccinimide active ester of Nα,Nε-di-Cbz-L-lysine. Both lysine amino groups are protected, while the carboxyl group is preactivated as an OSu ester. The reagent can therefore transfer a protected lysine acyl group to a suitable nucleophilic amine without generating the activated ester in situ.
The main practical advantage is convenience in amide formation. The main practical vulnerability is hydrolysis. Because the active ester can be consumed by water, storage history and moisture exposure can affect effective reactivity even when nominal chemical identity remains unchanged.
Product Information
| Product Name | Z-Lys(Z)-OSu |
| Catalog No. | AS4093 |
| CAS No. | 2116-83-8 |
| Molecular Formula | C26H29N3O8 |
| Molecular Weight | 511.53 g/mol |
| Chemical Identity | Nα,Nε-di-Cbz-L-lysine N-hydroxysuccinimide ester |
| Building Block Type | Activated NHS ester of protected lysine |
| Primary Applications | Amide formation, protected lysine incorporation, conjugation intermediates and short-fragment synthesis |
How the OSu Active Ester Reacts
A suitable amine attacks the activated lysine carbonyl and N-hydroxysuccinimide leaves, forming an amide bond. The same NHS-ester concept appears in many peptide and bioconjugation reagents. For comparison, Fmoc-OSu also contains a succinimidyl leaving group, but it transfers Fmoc protection rather than a protected lysine acyl group.
Why Both Lysine Amines Are Cbz-Protected
Protecting both Nα and Nε prevents internal or competing amine reactions during acyl transfer. After the desired amide is formed, the Cbz groups can be removed under compatible reductive conditions. This makes Z-Lys(Z)-OSu useful as a protected branch-point precursor or as a reagent for preparing lysine-containing intermediates.
Hydrolysis Can Explain Unexpectedly Low Conversion
NHS esters can lose activity through exposure to water. Dry solvent, controlled handling and tightly closed storage are therefore part of reaction performance, not merely storage recommendations. We consider active-ester integrity one of the first variables to check when conversion falls below expectation before simply increasing reagent equivalents.
From Building Block to Complete Peptide
Z-Lys(Z)-OSu is a reactive intermediate, not a finished assay reagent. When lysine branching, side-chain derivatization or other sequence-specific modifications are needed in a complete peptide, the route should account for Cbz removal and every other protecting group in the molecule. Alan Scientific can evaluate these constraints through our custom lysine-modified peptide synthesis service.
Procurement and QC Considerations
Confirm CAS 2116-83-8, C26H29N3O8, MW 511.53 g/mol and the Nα,Nε-di-Cbz/OSu structure. Where reactivity is critical, lot age, storage history and evidence of active-ester integrity may be more informative than nominal purity alone.
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
What does OSu mean in Z-Lys(Z)-OSu?
It denotes the N-hydroxysuccinimide active ester of the protected lysine carboxyl group.
Why are both lysine amino groups protected?
Dual Cbz protection prevents the α- and ε-amines from competing during the intended acyl-transfer reaction.
Why is moisture control important?
Water can hydrolyze NHS esters and reduce the amount of active reagent available for amide formation.
Related Technical Resources
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