Sialidase substrate specificity studies using Neu5Ac-sialosides (black bars) Neu5Acα2–3GalβpNP (17) and Neu5Acα2–6GalβpNP (18), Neu5Ac9NAc-sialosdies (white bars) Neu5Ac9NAcα2–3GalβpNP (1) and Neu5Ac9NAcα2–6GalβpNP (8), as well as Neu5,9Ac2-sialosides (grey bars) Neu5,9Ac2α2–3GalβpNP (19) and Neu5,9Ac2α2–6GalβpNP (20) as substrates.