4-Pentynoic acid NHS ester，50MG，SML4321-50MG，Sigma

Biochem/physiol Actions

4-Pentynoic acid NHS ester is a cell-permeable, bifunctional clickable label that combines an NHS ester and a terminal alkyne, enabling precise bioconjugation. The NHS ester selectively conjugates with primary amines on proteins, peptides, and other biomolecules, forming stable amide bonds in aqueous conditions. Its terminal alkyne supports click chemistry, specifically Cu(I)-catalyzed azide-alkyne cycloaddition, allowing covalent attachment to azide-modified tracers with minimal interference in biological systems. This dual reactivity makes it an ideal tool for selective labeling and tracking of biomolecules in complex biological systems, facilitating advanced bioconjugation strategies for cell imaging and the study of biomolecular interactions.