The landscape of peptide synthesis is constantly evolving, driven by the demand for more complex and therapeutically relevant peptide sequences. Central to this progress is the selection of appropriate building blocks, particularly protected amino acid derivatives. Among these, Fmoc-Thr(tBu)-OH (N-Fmoc-O-tert-butyl-L-threonine) has emerged as a standard and indispensable reagent for peptide chemists worldwide. This guide aims to illuminate its significance, assist procurement managers in making informed purchasing decisions, and highlight its benefits for R&D scientists.

Fmoc-Thr(tBu)-OH is a derivative of L-threonine, an essential amino acid, that is protected with the Fmoc group at the N-terminus and a tert-butyl (tBu) group on its side chain hydroxyl. The Fmoc group is favored in solid-phase peptide synthesis (SPPS) due to its lability under mild basic conditions, allowing for stepwise chain elongation without damaging the growing peptide. The t-butyl group on the threonine side chain is crucial for preventing unwanted side reactions, such as esterification or alkylation, during the synthesis process. Its stability during the Fmoc deprotection steps is a key advantage. This selective protection strategy ensures that only the desired amino acid residues are incorporated into the peptide chain, leading to higher purity and yield.

For professionals in pharmaceutical R&D and custom peptide synthesis companies, the consistent availability and quality of Fmoc-Thr(tBu)-OH are paramount. When considering a purchase, key factors include the purity of the compound, typically specified by HPLC analysis (often ≥99%), and the reliability of the manufacturer or supplier. Sourcing from established chemical suppliers, especially those with a strong presence in regions like China, can offer a balance of quality and cost-effectiveness. It is advisable to request a Certificate of Analysis (CoA) to verify the purity and specifications of the product before placing a bulk order. Understanding the CAS number, 71989-35-0, is also essential for accurate identification and procurement.

The application of Fmoc-Thr(tBu)-OH extends beyond basic peptide synthesis. It plays a critical role in the development of peptide-based therapeutics, diagnostic tools, and research probes. Its predictable behavior in SPPS workflows allows for the efficient synthesis of complex peptides that may exhibit enhanced biological activity or improved pharmacokinetic properties. By utilizing protected amino acids like Fmoc-Thr(tBu)-OH, researchers can confidently build intricate peptide structures, paving the way for groundbreaking discoveries in medicine and biotechnology. For any researcher or purchasing manager involved in peptide synthesis, ensuring a consistent and high-quality supply of Fmoc-Thr(tBu)-OH is a fundamental step towards achieving project success.