$516.00 - $1550.00
Z-D-Ala-Ala-OH is Cbz-D-Ala-L-Ala-OH, a stereodefined protected dipeptide with D-alanine at the N-terminal position and L-alanine at the C-terminal position. Its molecular formula and nominal mass are the same as the corresponding all-L protected Ala-Ala fragment, so stereochemistry is the defining analytical and procurement variable.
This makes Z-D-Ala-Ala-OH useful not only as a protected fragment but also as a controlled way to introduce one D residue into an analog series. Researchers can compare it directly with Z-Ala-Ala-OH, the corresponding L-Ala-L-Ala fragment when stereochemical effects are the experimental variable.
Product Information
| Product Name | Z-D-Ala-Ala-OH |
| Catalog No. | AS4090 |
| CAS No. | 74202-01-0 |
| Molecular Formula | C14H18N2O5 |
| Molecular Weight | 294.31 g/mol |
| Chemical Identity | Cbz-D-Ala-L-Ala-OH |
| Building Block Type | Cbz-protected stereodefined dipeptide |
| Primary Applications | D-residue peptide SAR, stereochemical standards, protected-fragment coupling and peptide intermediate synthesis |
Why One D Residue Can Change Peptide Behavior
Changing L-Ala to D-Ala reverses the geometry around one α-carbon without changing elemental composition. In a completed peptide, that can alter local backbone conformation, protease recognition and target binding. The magnitude of the effect depends on sequence position. Our overview of D-amino acids and other noncanonical residues in peptide design explains why matched analogs are often more informative than isolated substitutions.
LC-MS Cannot Prove D/L Identity
Z-D-Ala-Ala-OH and Z-Ala-Ala-OH both have C14H18N2O5 and MW 294.31 g/mol. Routine LC-MS therefore confirms composition but cannot identify which stereochemical variant is present. We recommend checking the CAS number, drawn structure and, where the project requires it, chiral or optical evidence.
Using a Preformed D-Ala-L-Ala Fragment
The protected fragment removes one downstream coupling and makes the D/L assignment explicit before longer assembly. This can be useful in solution-phase synthesis, convergent routes and libraries containing matched stereochemical controls. When the final target contains multiple D residues or other non-standard modifications, our stereochemically defined custom peptide synthesis service can evaluate the full sequence rather than the fragment in isolation.
Procurement and QC Considerations
Confirm CAS 74202-01-0, C14H18N2O5, MW 294.31 g/mol and D-Ala-L-Ala identity. If D- and L-containing variants are stored together, labeling discipline and structure-specific COA review are more useful than relying on mass or routine achiral HPLC 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
Is Z-D-Ala-Ala-OH the same as Z-Ala-Ala-OH?
No. They have the same formula and nominal mass but differ in the configuration of the N-terminal alanine.
Can LC-MS distinguish the two products?
No. Mass spectrometry alone does not distinguish enantiomeric or diastereomeric configuration when elemental composition is unchanged.
Why use the preformed dipeptide?
It provides a separately characterized D-Ala-L-Ala motif and removes one peptide-bond-forming step from downstream assembly.
Related Technical Resources
For other stereodefined fragments and unusual residues, browse Specialty Peptide Building Blocks.