Bioorthogonal metabolic glycoengineering of human larynx carcinoma (HEp-2) cells targeting sialic acid

• Arne Homann,
• Riaz-ul Qamar,
• Sevnur Serim,
• Petra Dersch and
• Jürgen Seibel

Beilstein J. Org. Chem. 2010, 6, No. 24, doi:10.3762/bjoc.6.24

• glycan structures of various types forming the individual, dynamic glycocalyx of each cell type. These glycolipids and glycoproteins often carry sialic acids, in humans N-acetylneuraminic acid (Neu5Ac, 1, Scheme 1), at their terminal position which mediate cell-cell recognition and signal transduction

• through the membrane of eukaryotic cells [3]. Neu5Hex (3) is a new substrate for metabolic glycoengineering which is proposed to be incorporated into the cell surface glycan structures. It was shown that carbohydrates in growth media contribute to alterations in glycosylation patterns in human cells [8

• Neu5Hex 3 guarantees its direct incorporation into the cell surface glycan patterns bypassing metabolic bottlenecks. Furthermore, the described genetic feedback inhibition by sialic acid leading to an accumulation of the fed Neu5Hex 3 ensures an efficient integration into the cell surface glycocalyx. A

Acid- mediated reactions under microfluidic conditions: A new strategy for practical synthesis of biofunctional natural products

• Katsunori Tanaka and
• Koichi Fukase

Beilstein J. Org. Chem. 2009, 5, No. 40, doi:10.3762/bjoc.5.40

• conditions enabled the preparation of key synthetic intermediates for oligosaccharides on a multi-gram scale, eventually leading to a total synthesis of the asparagine-linked oligosaccharide (N-glycan) [32]. A significant improvement has also been achieved for dehydration, which resulted in the industrial

• of mammalian N-glycans of the diverse structures, have motivated us to establish a practical and library-directed synthesis of the complex-type N-glycans on solid-support [32]; the initial target of our strategy is a sialic acid-containing N-glycan with asymmetric branching chains (Figure 1), which

• is difficult to obtain from natural sources. To prepare the target N-glycan as well as other diverse structures of this family in an efficient manner, we designed fragments a–d with N-phenyltrifluoroacetimidate as the leaving group, which can be efficiently glycosylated on solid-support to construct