Exo-alpha-sialidase that catalyzes the hydrolytic cleavage of the terminal sialic acid (N-acetylneuraminic acid, Neu5Ac) of a glycan moiety in the catabolism of glycolipids, glycoproteins and oligosacharides (PubMed:14613940, PubMed:22228546). Recognizes sialyl linkage positions of the glycan moiety as well as the supramolecular organization of the sialoglycoconjugate. Displays preference for alpha-(2->3)-sialylated GD1a and GT1B gangliosides over alpha-(2->8)-sialylated GD1b, in both monomeric forms and micelles. Hydrolyzes monomeric GM1 ganglioside, but has no activity toward the miscellar form (PubMed:14613940). Has lower sialidase activity for glycoproteins such as fetuin and TF/transferrin that carry a mixture of alpha-(2->3) and alpha-(2->6)-sialyl linkages. Cleaves milk oligosaccharide alpha-(2->3)-sialyllactose, but is inactive toward alpha-(2->6)-sialyllactose isomer. Has no activity toward colominic acid, a homomer of alpha-(2->8)-linked Neu5Ac residues (PubMed:14613940). Hydrolysis of alpha-(2->3)-, alpha-(2->6)-, alpha-(2->8)- glycosidic linkages of terminal sialic acid residues in oligosaccharides, glycoproteins, glycolipids, colominic acid and synthetic substrates. ganglioside GD1a + H2O = ganglioside GM1 + N-acetylneuraminate ganglioside GM1 + H2O = ganglioside GA1 + N-acetylneuraminate ganglioside GT1b + H2O = ganglioside GD1b + N-acetylneuraminate ganglioside GD1b + H2O = ganglioside GM1 + N-acetylneuraminate ganglioside GD3 + H2O = ganglioside GM3 + N-acetylneuraminate ganglioside GM3 + H2O = beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1)-ceramide + N-acetylneuraminate ganglioside GM2 + H2O = N-acetyl-beta-D-galactosaminyl-(1->4)-beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1')-ceramide + N-acetylneuraminate a neolactoside IV(3)-alpha-NeuAc-nLc4Cer(d18:1(4E)) + H2O = a neolactoside nLc4Cer(d18:1(4E)) + N-acetylneuraminate H2O + N-acetyl-alpha-neuraminosyl-(2->3)-beta-D-galactosyl-(1->4)-D-glucose = lactose + N-acetylneuraminate Optimum pH is 5.6. Expressed in skeletal muscle, fetal liver and embryonic carcinoma cell line NT2-D1. Belongs to the glycosyl hydrolase 33 family.