1. National Glycoengineering Research Center, Shandong Provincial Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, Jinan City, Shandong 250012, China
2. Key Laboratory of Chemical Biology of Ministry of Education, School of Pharmaceutical Sciences, Shandong University, Jinan City, Shandong 250012, China
3. Department of Chemistry, University of Konstanz, Konstanz D-78457, Germany