O-tert-Butyl-L-serine is primarily used in the field of peptide synthesis and pharmaceutical research. It serves as a key building block in the creation of modified peptides, where its tert-butyl group provides steric protection to the serine side chain during chemical reactions. This protection is crucial in preventing unwanted side reactions, ensuring the integrity and specificity of the peptide sequence. Additionally, it is employed in the development of peptide-based drugs, where modifications like tert-butyl groups can enhance the stability, bioavailability, and therapeutic efficacy of the compounds. Its application extends to the study of enzyme inhibitors and receptor ligands, where it helps in understanding molecular interactions and designing targeted therapies.