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Boc-Tyr(tBu)-Aib-Aib-OH is a protected tripeptide fragment containing Tyr followed by two consecutive Aib residues. The Tyr α-amino group is Boc-protected, the phenolic oxygen is tert-butyl-protected, and the C-terminal Aib carboxyl group remains available for further coupling.
Consecutive Aib residues are intentionally conformationally demanding. A related fragment, Fmoc-Aib-Aib-Aib-OH, extends this concept to three Aib residues under Fmoc protection.
Product Information
| Product Name | Boc-Tyr(tBu)-Aib-Aib-OH |
| Catalog No. | AS4159 |
| CAS No. | 194716-59-1 |
| Molecular Formula | C26H41N3O7 |
| Molecular Weight | 507.63 g/mol |
| Building Block Type | Boc/Tyr(tBu)-protected Tyr-Aib-Aib tripeptide fragment |
| Primary Applications | Aib-rich peptide synthesis; conformationally constrained peptide fragments; fragment coupling; helical peptide design |
Why Two Consecutive Aib Residues Matter
Aib (α-aminoisobutyric acid) is α,α-disubstituted and commonly used to favor compact helical or turn-like conformations. Two adjacent Aib residues can substantially reduce backbone conformational freedom relative to ordinary Ala-rich sequences. The effect should be evaluated in the complete peptide rather than assumed from the fragment alone.
A Preassembled Fragment Avoids Two Difficult Aib Junctions
Aib is sterically hindered at the α-carbon. Installing a preassembled Tyr-Aib-Aib fragment can remove repeated downstream formation of highly hindered Aib-containing peptide bonds. This can be useful when the same motif is used across an analog series.
Mixed Protecting Groups Define the Route
Boc on the N-terminus and tBu on Tyr are both acid-labile, but they serve different functions. The free terminal carboxyl supports fragment coupling. Before use, confirm that the next coupling and later deprotection conditions fit the complete protection scheme.
Procurement and QC
Confirm CAS 194716-59-1, sequence order Tyr-Aib-Aib, formula C26H41N3O7, MW 507.63 g/mol, and the Tyr(tBu) / N-Boc protection map. Sequence identity cannot be inferred from mass alone.
For Aib-rich or conformationally constrained targets, fragment use versus stepwise assembly can be evaluated in the context of the SPPS workflow and the complete sequence.
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 is Aib?
Aib is α-aminoisobutyric acid, an α,α-disubstituted noncanonical amino acid.
Why use a preformed Tyr-Aib-Aib fragment?
It fixes sequence order and can avoid repeated formation of sterically demanding Aib-containing peptide bonds.
Is Tyr already protected?
Yes. The phenolic hydroxyl is protected as Tyr(tBu), and the N-terminus is Boc-protected.
Related Technical Resources
Discuss constrained custom peptide synthesis