Ryosuke Matsubara

Gold–platinum bimetallic clusters for aerobic oxidation of alcohols under ambient conditions

We have developed gold/platinum alloyed bimetallic cluster catalysts supported on a cross-linked polystyrene derivative, which present much higher activity and selectivity than single metal gold or platinum clusters for aerobic oxidation of alcohols under ambient conditions.

Crystal structures of the CERT START domain with inhibitors provide insights into the mechanism of ceramide transfer.

The cytosolic protein CERT transfers ceramide from the endoplasmic reticulum to the Golgi apparatus where ceramide is converted to SM. The C-terminal START (steroidogenic acute regulatory protein-related lipid transfer) domain of CERT binds one ceramide molecule in its central amphiphilic cavity. (1R,3R)-N-(3-Hydroxy-1-hydroxymethyl-3-phenylpropyl)alkanamide (HPA), a synthesized analogue of ceramide, inhibits ceramide transfer by CERT. Here we report crystal structures of the CERT START domain in complex with HPAs of varying acyl chain lengths. In these structures, one HPA molecule is buried in the amphiphilic cavity where the amide and hydroxyl groups of HPA form a hydrogen-bond network with specific amino acid residues. The Omega1 loop, which has been suggested to function as a gate of the cavity, adopts a different conformation when bound to HPA than when bound to ceramide. In the Omega1 loop region, Trp473 shows the largest difference between these two structures. This residue exists inside of the cavity in HPA-bound structures, while it is exposed to the outside of the protein in the apo-form and ceramide-bound complex structures. Surface plasmon resonance experiments confirmed that Trp473 is important for interaction with membranes. These results provide insights into not only the molecular mechanism of inhibition by HPAs but also possible mechanisms by which CERT interacts with ceramide.

Catalytic Carbanion Reactions: Formation and Reaction of Carbanions from Ester or Amide Equivalents Using Catalytic Amounts of Bases

We describe here carbanion reactions using catalytic amounts of bases. The carbanions formed are different from conventional carbanions in which stoichiometric amounts of bases are needed for the formation. Two types of reactions using such carbanions from amide (imido) and ester equivalents are discussed.

C–C Bond Formation Through Addition of C–M to C O, C N, and C N Bonds

This chapter covers carbon–carbon bond formations based on addition of organotransition metal compounds (C–M) to CO (carbonyl compounds and carbon dioxide), CN (imines and isocyanates), and CN (nitriles and isocyanides) bonds. A series of reactions reported between 1993 and 2005 are discussed comprehensively. Not only reactions using a stoichiometric amount of an organometallic compound but also catalytic processes are included, even though their catalytic mechanisms are only postulated in most cases.