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Z-Gly-Gly-Gly-OH is an N-Cbz-protected triglycine fragment with a free C-terminal carboxyl group. It provides a defined Gly3 unit for protected-fragment synthesis and is particularly useful when a short, low-bulk peptide spacer is required.
Gly3 is often treated as a generic “flexible linker,” but linker length can affect the spacing and conformational sampling of the groups attached to it. A three-glycine segment therefore deserves the same sequence-level planning as any other peptide motif.
Product Information
| Product Name | Z-Gly-Gly-Gly-OH |
| Catalog No. | AS4092 |
| CAS No. | 2566-20-3 |
| Molecular Formula | C14H17N3O6 |
| Molecular Weight | 323.31 g/mol |
| Chemical Identity | Cbz-Gly-Gly-Gly-OH |
| Building Block Type | Cbz-protected tripeptide fragment |
| Primary Applications | Flexible peptide spacers, fragment coupling, linker-containing peptides and convergent assembly |
Why Gly3 Is Used as a Short Flexible Spacer
Glycine has no side-chain carbon beyond hydrogen, so a Gly3 segment introduces very little steric bulk while allowing broad backbone conformational sampling. This can help separate a peptide pharmacophore from a label, carrier or secondary binding element. A longer spacer is available as Z-Gly-Gly-Gly-Gly-OH (Gly4) when an additional glycine residue is preferred.
Gly3 Is Not Chemically Equivalent to PEG
Gly3 and short PEG linkers can both increase spacing, but they differ in polarity, hydrogen-bonding behavior, enzymatic susceptibility and conformational preferences. We recommend selecting between peptide and PEG spacing according to the final construct rather than treating them as interchangeable lengths.
Why Use a Preformed Gly3 Fragment?
A preassembled Gly3 unit removes two individual peptide-bond-forming operations from the downstream route and provides a separately characterized chain length. This can be useful in solution-phase assembly or when the same linker motif is used across a series. For longer targets, our SPPS practical guide explains how small per-cycle inefficiencies can accumulate with chain length.
Procurement and QC Considerations
Confirm CAS 2566-20-3, C14H17N3O6, MW 323.31 g/mol and the exact Gly3 chain length. LC-MS is valuable for distinguishing neighboring oligoglycine lengths, while HPLC helps assess deletion or extension-related impurities.
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 Gly3 the same as a PEG3 linker?
No. Both provide spacing, but their chemical composition, flexibility and enzymatic behavior are different.
Does the fragment have a free carboxyl group?
Yes. The C-terminal glycine carboxyl remains available for activation and further coupling.
When should I consider Gly4 instead?
Gly4 may be useful when a slightly longer and more flexible peptide spacer is needed, but the final construct should determine the linker length.
Related Technical Resources
Alan Scientific can incorporate Gly-rich spacers into labeled, conjugated or otherwise modified sequences through our custom peptide synthesis and modification service.