Purification and Properties of an α-l-Fucosidase from Rat Epididymis

An α-l-fucosidase has been purified from rat epididymis by fractionation of extracts with ammonium sulfate and subsequent chromatography on ion exchange celluloses. It is a glycoprotein with a molecular weight of 210,000 to 220,000 and dissociates in the presence of mercaptoethanol and guanidine hydrochloride or sodium dodecyl sulfate. The dissociated material behaves as two components with molecular weights of approximately 47,000 and 60,000, thus suggesting two pairs of dissimilar subunits. A preliminary amino acid and carbohydrate composition is reported. Other glycosidases of rat epididymis, α-d-mannosidase, β-d-N-acetylglucosaminidase, and β-d-galactosidase have been partially purified from the same extract. All were active against a variety of glycoprotein and glycopeptide substrates. The purified fucosidase preparation is stable, is essentially free from other glycosidases with the exception of small amounts of N-acetylglucosaminidase activity, and it catalyzes the hydrolysis of p-nitrophenyl-α-l-fucoside. Studies with glycopeptides show quantitative release of fucose by the purified enzyme from the tryptic glycopeptide of the hormone-specific chain of bovine luteinizing hormone and from a peptide of horse immunoglobulin G. A general method has been developed for quantitative determination by gas-liquid chromatography of the monosaccharides released by enzymic hydrolysis of glycoproteins and glycopeptides.