Product Overview

Fmoc-Ser(tBu)-OH (CAS 71989-33-8; catalog AS0706) is an Fmoc-protected L-serine building block with the side-chain hydroxyl protected as a tert-butyl ether. Its alpha-carboxyl group remains free for peptide coupling. This derivative is used to incorporate Ser into peptides assembled by conventional Fmoc/tBu solid-phase synthesis.

Quality Specifications and Ordering

Purity: Alan Scientific supplies Fmoc-Ser(tBu)-OH at >99% purity.

Catalog pack sizes: 25 g, 100 g, 500 g, and 1 kg.

Quality documentation: See Product Documents below for lot-specific COA request details. Review the analytical methods and results reported for the supplied batch.

Quotation: Email [email protected] with AS0706, the pack size, total quantity, delivery destination, and required date. Confirm availability and dispatch lead time before ordering.

For Gly-Ser spacer projects, calculate Ser consumption separately from Gly. Confirm O-tBu protection and any additional analytical requirements for the selected route.

Hydroxyl Protection during Chain Assembly

The side-chain ether limits unwanted reactions at the serine hydroxyl during the protected synthesis stage. Fmoc is removed during elongation, while the tBu group is retained under routine basic deprotection conditions and removed during a compatible final acidic treatment.

This protection pattern is different from the tert-butyl ester used to mask the side-chain carboxyl groups of Asp and Glu. The distinction helps prevent confusion when reading abbreviated building-block names or matching a structure to an order.

Serine-Containing Peptides and Spacer Sequences

Applications include Ser-containing research peptides, hydroxyl-side-chain analogue studies, and Gly-Ser spacer segments. Serine introduces a hydroxymethyl side chain after deprotection, while glycine contributes an achiral, minimally substituted backbone position. The behavior of a spacer depends on its complete length and sequence.

Fmoc-Ser(tBu)-OH is not a pre-phosphorylated or pre-glycosylated serine building block. Projects requiring those modifications need a defined route and compatible protection strategy. Similarly, keeping the hydroxyl protected does not by itself prevent aggregation in a difficult resin-bound peptide.

For a Gly-Ser spacer sequence, compare Fmoc-Gly-OH as the complementary achiral building block and specify the intended residue order.

tBu and OtBu Do Not Describe the Same Functional Group

The (tBu) notation in Fmoc-Ser(tBu)-OH describes a tert-butyl ether on the serine side-chain hydroxyl group. It should not be confused with the (OtBu) notation used for tert-butyl esters of carboxyl-containing amino acids such as Fmoc-Glu(OtBu)-OH.

These names describe different functional groups and different chemical entities. The products are not interchangeable.

Selection Notes for Serine-Containing Sequences

• Confirm that both the N-terminal Fmoc group and side-chain O-tert-butyl protection match the synthesis plan.

• Distinguish Fmoc-Ser(tBu)-OH from Fmoc-Ser-OH and protected threonine derivatives.

• Verify CAS number 71989-33-8 and the current lot documentation before ordering.

A related hydroxyl-containing Fmoc building block is Fmoc-Thr(tBu)-OH. It contains threonine rather than serine and should not be treated as a substitute.

Product Documents

A Safety Data Sheet (SDS / MSDS) is available for this product to support laboratory handling, storage and safety assessment.

MSDS_Fmoc-Ser-tBu-OH_AS0706

Certificates of Analysis are batch-specific. Please contact us to request a COA, and we will provide it by email.

Frequently Asked Questions

Can I include Fmoc-Ser(tBu)-OH in a Gly-Ser linker procurement list?

Yes. List AS0706 and the protected Ser quantity alongside the separately calculated Gly requirement. The catalog pack sizes are 25 g, 100 g, 500 g, and 1 kg. The two building blocks are ordered individually; this does not imply a pre-mixed linker reagent or a fixed kit.

Is the tBu group in Fmoc-Ser(tBu)-OH an ester?

No. It protects the side-chain hydroxyl as an ether. The alpha-carboxyl group remains free for coupling.

Does this reagent introduce phosphoserine?

No. It introduces a protected serine residue. A phosphate modification requires additional defined chemistry or a different building block.

Research Use Only

For research use only. Not for human or veterinary use.