AAT Bioquest offers a comprehensive selection of FMOC-Asp(Dye) building blocks designed for in-sequence aspartic acid (Asp) labeling during solid-phase peptide synthesis (SPPS). These FMOC-protected amino acid derivatives enable direct incorporation of fluorophores, quenchers, and biotin tags at specific Asp positions within peptide sequences, making them essential tools for developing FRET-based protease substrates, fluorescent peptide probes, and biotinylated peptides for affinity applications.

These fluorophore-labeled FMOC-Asp building blocks enable direct incorporation of fluorescent dyes at Asp residues during SPPS. They are commonly used as FRET donors in protease substrate development, with FAM and EDANS being classic choices for pairing with DABCYL quenchers, while TAMRA and TF3 offer red-shifted alternatives for applications requiring reduced autofluorescence interference.

Dark quencher-labeled FMOC-Asp building blocks are essential components for constructing FRET-based peptide substrates. When incorporated alongside a fluorescent donor, these quenchers efficiently absorb emitted light without generating fluorescence, enabling "turn-on" assays where proteolytic cleavage separates donor and quencher to restore fluorescence.

This PEG-linked biotin FMOC-Asp derivative enables site-specific biotinylation of peptides at Asp residues during SPPS. The PEG spacer provides excellent solubility and reduces steric hindrance, improving streptavidin binding efficiency compared to direct biotin conjugates.