ContentsI. General Introduction 443 II. Aldol Addition with Aldolases 443 1. Introduction 443 2. DHAP-Dependent Aldolases 447 2.1. General Background 447 2.2. Synthetic Applications 449 3. Pyruvate-and Phosphoenolpyruvate-Dependent Aldolases 453 3.1. N-Acetylneuraminic Acid Aldolase and NeuAc Synthetase 453 3.2. 3-Deoxy-D-manno-2-octulosonate (KDO) Aldolase and 3-Deoxy-D-manno-2-octulosonate 8-Phosphate (KDO-8-P) Synthetase 456 3.3. Other Pyruvate-and Phosphoenolpyruvate-Dependent Aldolases 457 4. 2-Deoxyribose-5-phosphate Aldolase 457 5. Glycine-Dependent Aldolases 459 III. Enzymatic Glycosidation 460 1. Glycosidases and Transglycosidases 460 2. Glycosyltransferases 462 2.1. Non-Leloir Glycosyltransferases 462 2.2. Leloir-type Glycosyltransferases 463 IV. Concluding Remarks 469 V. References 469

Human R-1,3-fucosyltransferase V (FucT V), which catalyzes the transfer of L-fucose moiety from guanosine diphosphate -L-fucose (GDP-Fuc) to an acceptor sugar to form sialyl Lewis x (sLe x ), was shown to proceed through an ordered, sequential mechanism by product inhibition studies. The designed azatrisaccharide propyl 2-acetamido- (2), prepared by covalently linking the N-group of -L-homofuconojirimycin (1) to the 3-OH of LacNAc through an ethylene unit, in the presence of GDP was found to be an effective inhibitor of FucT V. In the presence of 30 µM GDP, the concentration of 2 necessary to cause 50% inhibition was reduced 77-fold to 31 µM. Presumably, the azatrisaccharide and GDP form a complex which mimics the transition state of the enzymatic reaction. Given the low affinity of FucT V for its substrate LacNAc (K m ) 35 mM), the designed azatrisaccharide in the presence of GDP represents the most potent synergistic inhibitor complex reported so far.

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Gold nanoparticles have been used for centuries, both for decoration and in medical applications. More recently, many of the major advances in cluster chemistry have involved welldefined clusters containing tens or hundreds of atoms, either with or without a ligand shell. In this paper we report the synthesis of two gold/lead clusters, [Au 8 Pb 33 ] 6− and [Au 12 Pb 44 ] 8− , both of which contain nido [Au@Pb 11 ] 3− icosahedra surrounding a core of Au atoms. Analogues of these large clusters are not found in the corresponding Ag chemistry: instead, the Ag-centered nido icosahedron, [Ag@Pb 11 ] 3− , is the only isolated product. The structural chemistry, along with the mass spectrometry which shows the existence of [Au 2 Pb 11 ] 2− but not [Ag 2 Pb 11 ] 2− , leads us to propose that the former species is the key intermediate in the growth of the larger clusters. Density functional theory indicates that secondary π-type interactions between the [Au@Pb 11 ] 3− ligands and the gold core play a significant part in stabilizing the larger clusters.