A β-D-lactose ligand equipped with an amine-functionalized linker through a short ethyl spacer. The primary amine can be covalently coupled with N-hydroxysuccinimide (NHS) activated esters to form stable amide bonds, providing a straightforward route to conjugate the ligand onto NHS-activated molecules and surfaces. This compound provides a lactose (Galβ1-4Glc) building block for glycoconjugate synthesis and the construction of probes for galactose-recognizing proteins, including galectins and the hepatic asialoglycoprotein receptor. It is a substrate for sialyltransferases and other glycosyltransferases.