Molecular basis for glycan recognition and reaction priming of eukaryotic oligosaccharyltransferase.

Oligosaccharyltransferase (OST) is the central enzyme of N-linked protein glycosylation. It catalyzes the transfer of a pre-assembled glycan, GlcNAcManGlc, from a dolichyl-pyrophosphate donor to acceptor sites in secretory proteins in the lumen of the endoplasmic reticulum. Precise recognition of the fully assembled glycan by OST is essential for the subsequent quality control steps of glycoprotein biosynthesis.

Dinuclear thiolato-bridged arene ruthenium complexes: from reaction conditions and mechanism to synthesis of new complexes.

Several dinuclear thiophenolato-bridged arene ruthenium complexes [(η--MeCHPr)Ru(μ-SCH-R)] (R = H, NO, F) could so far only be obtained in fair yields using the synthetic route established in the early 2000s. With much less reactive aliphatic thiols or with bulky thiols, the reactions become even less efficient and the desired complexes are obtained with low yields or not at all. We employed density functional theory (DFT) calculations to gain a fundamental understanding of the reaction mechanisms leading to the formation of dithiolato and trithiolato complexes starting from the dichloro(-cymene)ruthenium(ii) dimer [(η--MeCHPr)Ru(μ-Cl)Cl].