Maras M, De Bruyn A, Schraml J, Herdewijn P, Claeyssens M, Fiers W, Contreras R
Laboratory of Molecular Biology, Flanders Interuniversity Institute for Biotechnology and University of Ghent, Belgium.
Eur J Biochem. 1997 May 1;245(3):617-25. doi: 10.1111/j.1432-1033.1997.00617.x.
We have characterized the primary structures of the predominant N-linked oligosaccharides on cellobiohydrolase I from the filamentous fungus Trichoderma reesei RUTC30. Different enzymatic and chromatographic techniques were used to analyze six oligosaccharides. The combined data showed that the fungal carbohydrates have a core structure that is identical to the mammalian N-linked core. In the bulk of the N-glycans, the alpha-1,3 arm is extended with two mannoses and a glucose, suggesting incomplete processing of the oligosaccharides in the endoplasmic reticulum. The alpha-1,6 arm shows a remarkable heterogeneity: in addition to alpha-1,2-Man and alpha-1,6-Man, the presence of a terminal mannose alpha-1,6-phosphodiester was observed. This latter substituent has not been characterized before on mannosidase-processed N-glycan and its function and synthesis pathway are entirely unknown. The predominant N-glycans on cellobiohydrolase I can be represented as follows: GlcMan8GlcNAc2, GlcMan7GlcNAc2, Man7GlcNAc2, ManPGlcMan7GlcNAc2, GlcMan5GlcNAc2 and Man5GlcNAc2.
我们已对丝状真菌里氏木霉RUTC30的纤维二糖水解酶I上主要的N-连接寡糖的一级结构进行了表征。采用了不同的酶法和色谱技术来分析六种寡糖。综合数据表明，真菌碳水化合物具有与哺乳动物N-连接核心相同的核心结构。在大部分N-聚糖中，α-1,3臂延伸有两个甘露糖和一个葡萄糖，这表明寡糖在内质网中的加工不完全。α-1,6臂表现出显著的异质性：除了α-1,2-甘露糖和α-1,6-甘露糖外，还观察到末端甘露糖α-1,6-磷酸二酯的存在。这种后一种取代基在甘露糖苷酶处理的N-聚糖上之前尚未得到表征，其功能和合成途径完全未知。纤维二糖水解酶I上主要的N-聚糖可表示如下：GlcMan8GlcNAc2、GlcMan7GlcNAc2、Man7GlcNAc2、ManPGlcMan7GlcNAc2、GlcMan5GlcNAc2和Man5GlcNAc2。
