Used in solid-phase peptide synthesis to introduce a biotin-labeled lysine residue into peptides. The Fmoc group allows for orthogonal protection, enabling stepwise assembly of complex peptides on resin. Once incorporated, the biotin tag facilitates detection, purification, or immobilization of the peptide via streptavidin-biotin interaction, which is widely used in assays like ELISA, pull-down experiments, and surface binding studies. The D-configuration provides resistance to proteolytic degradation, making it useful in designing stable peptide probes or enzyme inhibitors. Commonly applied in drug discovery, biochemical research, and diagnostic tool development.