Nakao Y, Kozutsumi Y, Funakoshi I, Kawasaki T, Yamashina I, Mutsaers J H, Van Halbeek H, Vliegenthart J F
Department of Biological Chemistry, Faculty of Pharmaceutical Sciences, Kyoto University.
J Biochem. 1987 Jul;102(1):171-9. doi: 10.1093/oxfordjournals.jbchem.a122030.
The carbohydrate portions of beta-galactosidase from Aspergillus oryzae were found to be composed of two types of sugar chains. They were released equally well with endo-beta-N-acetylglucosaminidase H, but were distinct in their chain length. The long sugar chains (fraction I), corresponding to 4% of the total carbohydrate chains, were composed of galactomannan-type oligosaccharides, which consisted of mannose, galactose, glucose, and glucosamine in the molar ratios of 30.0, 16.4, 1.4, and 2.1 per mol of aspartic acid, respectively. The short sugar chains (fraction II), corresponding to 96% of the total carbohydrate chains, consisted of mannose, galactose, glucose, and glucosamine in the molar ratios of 9.4, 0.6, 0.3, and 1.7 per mol of aspartic acid, respectively. Both types of sugar chains were fractionated into neutral and acidic subfractions. The neutral subfraction of fraction I (I-N), corresponding to 1% of the total carbohydrate chains, was very heterogeneous in length and was resistant to digestion with alpha-mannosidase and beta-galactosidase. The neutral subfraction of fraction II (II-N), corresponding to 91% of the total carbohydrate, was composed of a mixture of oligosaccharides with oligomanneoside chains (Mann GlcNAcol). The major components were similar to high mannose-type oligosaccharides of mammalian origin in their composition and size (n = 5-9). However, digestion of II-N with alpha 1,2-mannosidase produced considerable amounts of Man6GlcNAcol, an unusual product in the case of high mannose-type oligosaccharides of mammalian origin, in addition to the common one, Man5GlcNAcol.
米曲霉β-半乳糖苷酶的碳水化合物部分被发现由两种类型的糖链组成。它们被内切β-N-乙酰葡糖胺酶H同等程度地释放，但链长不同。长糖链（组分I），占总碳水化合物链的4%，由半乳甘露聚糖型寡糖组成，每摩尔天冬氨酸中甘露糖、半乳糖、葡萄糖和葡糖胺的摩尔比分别为30.0、16.4、1.4和2.1。短糖链（组分II），占总碳水化合物链的96%，每摩尔天冬氨酸中甘露糖、半乳糖、葡萄糖和葡糖胺的摩尔比分别为9.4、0.6、0.3和1.7。两种类型的糖链都被分离为中性和酸性亚组分。组分I的中性亚组分（I-N），占总碳水化合物链的1%，长度非常不均一，且对α-甘露糖苷酶和β-半乳糖苷酶的消化具有抗性。组分II的中性亚组分（II-N），占总碳水化合物的91%，由具有寡甘露糖苷链（Mann GlcNAcol）的寡糖混合物组成。其主要成分在组成和大小（n = 5-9）上与哺乳动物来源的高甘露糖型寡糖相似。然而，用α1,2-甘露糖苷酶消化II-N除了产生常见的Man5GlcNAcol外，还产生了相当数量的Man6GlcNAcol，这在哺乳动物来源的高甘露糖型寡糖中是一种不寻常的产物。
