Human milk contains a variety of biologically important oligosaccharides which reflect the lactating mothers Lewis blood group. [1] Antigens N3, known as N3 major and N3 minor, are examples of such milk-derived octasaccharides (Scheme 1). [2] N3 major, difucosyllacto-N-hexose (1), is the major component of N3 antigens containing Le a and Le x moieties. N3 minor, difucosyllacto-N-neohexaose (2), contains two Le x units and a lactose unit. The trisaccharide Le x is one of the carbohydrate determinants of blood groups and is known to be a tumor-related antigen. [3] The N3 antigens containing one or two Le x units were also overexpressed in various tumors, including gastrointestinal cancer cells. Although the synthesis of 1 and 2 has been reported, [4,5] little is know regarding the function of 2. We describe here the synthesis of 2 by using the one-pot strategy based on anomeric reactivity, [6] and the use of this glycan as a model to develop photocleavable arrays on porous silicon suitable for direct characterization by mass spectrometry.
Carbohydrate arrays are becoming powerful tools in glycobiology and glycomics. [7] We have recently reported the formation of a covalent array of complex oligosaccharides on glass slides [8] and microtiter plates for high-throughput analysis of sugar-protein interactions. [9] The microplate