Bouquelet S, Spik G, Montreuil J
Biochim Biophys Acta. 1978 Feb 10;522(2):521-30. doi: 10.1016/0005-2744(78)90084-0.
The beta-D-mannosidase (beta-D-mannoside mannohydrolase, EC 3.2.1.25) from culture filtrate of Aspergillus niger has been purified in large amounts by fractionation with (NH4)2SO4 and DEAE-cellulose chromatography. The removal of traces of alpha-D-galactosidase was performed on a Sepharose-epsilon-aminocaproyl-galactosylamine column. The final enzyme preparation (specific activity 188 units) has no other glycosidase activity and is judged homogeneous. The enzyme has a molecular weight of 130 000 +/- 5000 and an isoelectric point of 4.7. The amino acid composition of the enzyme is characterized by high proportion of acidic amino acids and no cysteine residues and a single chain structure of the enzyme is suggested. The enzyme shows maximum activity on p-nitrophenyl-beta-D-mannopyrano-side at pH 3.5 and at 55 degrees C. The presence of 80% of beta-sheet structure in the protein and 20.8% of monosaccharides (Gal : 1.3; Man : 7; GlcNAc : 1) could explain this relative high heat stability (up to 2 h at 55 degrees C). Enzyme activity is inhibited by mannose (Ki = 7.85 mM) and the specificity is examined.
黑曲霉培养滤液中的β-D-甘露糖苷酶（β-D-甘露糖苷甘露水解酶，EC 3.2.1.25）已通过硫酸铵分级分离和DEAE-纤维素色谱法大量纯化。在琼脂糖-ε-氨基己酰-半乳糖胺柱上去除痕量的α-D-半乳糖苷酶。最终的酶制剂（比活性为188单位）没有其他糖苷酶活性，且判定为均一。该酶的分子量为130 000±5000，等电点为4.7。该酶的氨基酸组成特点是酸性氨基酸比例高，没有半胱氨酸残基，提示该酶为单链结构。该酶在pH 3.5和55℃时对对硝基苯基-β-D-甘露吡喃糖苷表现出最大活性。蛋白质中80%的β-折叠结构和20.8%的单糖（半乳糖：1.3；甘露糖：7；N-乙酰葡糖胺：1）的存在可以解释这种相对较高的热稳定性（在55℃下可达2小时）。酶活性受到甘露糖的抑制（Ki = 7.85 mM），并对其特异性进行了检测。
