There has much discussion on social media about which sugar is the most biologically and chemically exciting. Most people opt for the sialic acids, whilst a select group favour fucose. Mannose, which plays myriad biological roles and whose chemistry is dominated by its axial O2 group is a strong candidate. Mannans play key structural and recognition roles in biology and cellular function. β-linked mannans are exemplified by robust plant structural polysaccharides, α-linked mannans form the cell wall of yeast and the core of eukaryotic N-glycans (and of the viruses that infect them).
In this lecture I shall review some conformational aspects of mannoside enzymology with examples from α- and β-mannosidases before going on to discuss new, currently unpublished, work in three areas of mannoside chemistry: the enzymology (both mannoside phosphorylases / GDP-Man dependent mannosyltransferases) of the synthesis of β-1,2 linked mannogen in the Leishmanial parasite, the development of new activity-based probes for α-mannosidase inhibitor discovery and the unusual catalytic mechanism of N-glycan processing endomannosidases where evidence for a 1,2 anhydro “epoxide” intermediate will be discussed.