56881-52-8Relevant articles and documents
Characterization of the single-subunit oligosaccharyltransferase STT3A from Trypanosoma brucei using synthetic peptides and lipid-linked oligosaccharide analogs
Ramírez, Ana S.,Boilevin, Jérémy,Biswas, Rasomoy,Gan, Bee Ha,Janser, Daniel,Aebi, Markus,Darbre, Tamis,Reymond, Jean-Louis,Locher, Kaspar P.
, p. 525 - 535 (2017/06/09)
The initial transfer of a complex glycan in protein N-glycosylation is catalyzed by oligosaccharyltransferase (OST), which is generally a multisubunit membrane protein complex in the endoplasmic reticulum but a single-subunit enzyme (ssOST) in some protists. To investigate the reaction mechanism of ssOST, we recombinantly expressed, purified and characterized the STT3A protein from Trypanosoma brucei (TbSTT3A). We analyzed the in vitro activity of TbSTT3A by synthesizing fluorescently labeled acceptor peptides as well as lipid-linked oligosaccharide (LLO) analogs containing a chitobiose moiety coupled to oligoprenyl carriers of distinct lengths (C10, C15, C20 and C25) and with different double bond stereochemistry. We found that in addition to proline, charged residues at the +1 position of the sequon inhibited glycan transfer. An acidic residue at the -2 position significantly increased catalytic turnover but was not essential, in contrast to the bacterial OST. While all synthetic LLO analogs were processed by TbSTT3A, the length of the polyprenyl tail, but not the stereochemistry of the double bonds, determined their apparent affinity. We also synthesized phosphonate analogs of the LLOs, which were found to be competitive inhibitors of the reaction, although with lower apparent affinity to TbSTT3A than the active pyrophosphate analogs.
Rationally designed short polyisoprenol-linked PglB substrates for engineered polypeptide and protein N-glycosylation
Liu, Feng,Vijayakrishnan, Balakumar,Faridmoayer, Amirreza,Taylor, Thomas A.,Parsons, Thomas B.,Bernardes, Goncalo J.L.,Kowarik, Michael,Davis, Benjamin G.
supporting information, p. 566 - 569 (2014/02/14)
The lipid carrier specificity of the protein N-glycosylation enzyme C. jejuni PglB was tested using a logical, synthetic array of natural and unnatural C10, C20, C30, and C40 polyisoprenol sugar pyrophosphates, including those bearing repeating cis-prenyl units. Unusual, short, synthetically accessible C20 prenols (nerylnerol 1d and geranylnerol 1e) were shown to be effective lipid carriers for PglB sugar substrates. Kinetic analyses for PglB revealed clear KM-only modulation with lipid chain length, thereby implicating successful in vitro application at appropriate concentrations. This was confirmed by optimized, efficient in vitro synthesis allowing >90% of Asn-linked β-N-GlcNAc-ylated peptide and proteins. This reveals a simple, flexible biocatalytic method for glycoconjugate synthesis using PglB N-glycosylation machinery and varied chemically synthesized glycosylation donor precursors.
Selective C - S bond formation via Fe-catalyzed allylic substitution
Jegelka, Markus,Plietker, Bernd
supporting information; experimental part, p. 3462 - 3465 (2009/12/05)
In contrast to the formation of C - O and C - N bonds it was only recently that the selective C - S bond formation by means of transition metal complexes moved more into the center of research. This is somewhat surprising given the fact that the sulfur at
