Wan C C, Muldrey J E, Li S C, Li Y T
J Biol Chem. 1976 Jul 25;251(14):4384-8.
beta-D-Mannosidase (EC 3.2.1.25), a useful tool for the structural studies of heterosaccharide chains, has been isolated in a highly purified form from the fruiting bodies of the mushroom Polyporus sulfureus. This mushroom is unique among reported sources of this enzyme in that it has the advantage of being almost free of alpha-mannosidase activity. The purification procedure involves ammonium sulfate fractionation followed by Sephadex G-100 filtration and chromatography on columns of DEAE-cellulose and hydroxylapatite. The final enzyme preparation gives essentially a single band on disc gel electrophoresis. The purified enzyme liberates the beta-D-mannopyranosyl unit from various natural substrates such as the core glycopeptide, Man(GlcNAc)2-Asn isolated from ovalbumin, from Taka-amylase A, and from human alpha1-acid glycoprotein. It also hydrolyzes (Man)2-GlcNAc from the urine of an alpha-mannosidosis patient, 1,4-D-mannobiose and mannotriose isolated from ivory nut mannan, 4-O-beta-D-mannopyranosyl-L-rhamnose, 6-O-beta-D-mannopyranosyl-D-galactose and 4-O-beta-D-mannopyranosyl-N-acetylglucosamine. The molecular weight of this enzyme is estimated to be about 64,000 by gel filtration. For p-nitrophenyl-beta-D-mannopyranoside, the pH optimum is between 2.4 and 3.4 and the Km is 1.6 mM.
β-D-甘露糖苷酶（EC 3.2.1.25）是用于杂糖链结构研究的一种有用工具，已从硫黄多孔菌的子实体中以高度纯化的形式分离出来。在已报道的该酶来源中，这种蘑菇很独特，因为它几乎没有α-甘露糖苷酶活性。纯化过程包括硫酸铵分级分离，随后进行葡聚糖凝胶G-100过滤以及在DEAE-纤维素和羟磷灰石柱上进行层析。最终的酶制剂在圆盘凝胶电泳上基本呈现单一谱带。纯化后的酶能从各种天然底物中释放出β-D-甘露吡喃糖基单元，如核心糖肽、从卵清蛋白中分离出的Man(GlcNAc)2-Asn、从高峰淀粉酶A以及从人α1-酸性糖蛋白中分离出的该单元。它还能水解α-甘露糖苷贮积症患者尿液中的(Man)2-GlcNAc、从象牙果甘露聚糖中分离出的1,4-D-甘露二糖和甘露三糖、4-O-β-D-甘露吡喃糖基-L-鼠李糖、6-O-β-D-甘露吡喃糖基-D-半乳糖以及4-O-β-D-甘露吡喃糖基-N-乙酰葡糖胺。通过凝胶过滤估计该酶的分子量约为64,000。对于对硝基苯基-β-D-甘露吡喃糖苷，最适pH在2.4至3.4之间，Km为1.6 mM。
