Katharina Pahnke

Synthesis of a Bioreversibly Masked Lipophilic Adenosine Diphosphate Ribose Derivative

The design of a bioreversibly protected lipophilic sugar nucleotide as a potential membrane‐permeable precursor of adenosine diphosphate ribose (ADPR) is described. ADPR is the most potent activator of the transient receptor potential melastatin 2 (TRPM2) ion channel. Membrane‐permeable, lipophilic derivatives of ADPR are of great interest as tools for study of the mechanism of TRPM2. The approach described here was based on our recently disclosed “DiPPro” and “TriPPPro” prodrug approaches developed for the intracellular delivery of nucleotides. A lipophilic, bioreversibly masked ADPR analogue containing an enzymatically cleavable 4‐pentanoyloxybenzyl (PB) mask at the phosphate moiety next to the 5′‐position of adenosine, together with O‐acetyl groups, was prepared in high yields. Chemical and enzymatic hydrolysis studies in phosphate buffer (pH 7.3) were performed to assess chemical stability and possible (selective) enzymatic demasking of the ADPR analogue. HPLC‐MS revealed that the PB group was readily cleaved enzymatically. In addition, the formation of partially deacetylated ADPR compounds and also of fully unprotected ADPR was observed.

Corrigendum: Radiocarbon constraints on the extent and evolution of the South Pacific glacial carbon pool.

Nature Communications 7: Article number: 11487 10.1038/ncomms11487 (2016); Published: May092016; Updated: June032016 The affiliation details for R. De Pol-Holz are incorrect in this Article. The correct affiliation details for this author are given below: GAIA-Antartica, Universidad de Magallanes, Punta Arenas 01855, Chile.

Tagging Glycoproteins with Fluorescently Labeled GDP-Fucoses by Using α1,3-Fucosyltransferases.

Fucose‐containing glycans mediate a variety of biological processes, but there is little information on reaction processes and mechanisms mediated by fucosyltransferases. We recently reported on fluorescently labeled GDP‐β‐L‐fucose‐ATTO 550, which enabled monitoring of α1,3‐fucosyltransferase activity. Here we present an extension to the previously described results, based on the synthesis of a fluorescein‐isothiocyanate (FITC)‐labeled and two carboxyfluorescein‐labeled (FAM‐labeled) NDP‐β‐L‐fucose derivatives, and applied all four compounds in labeling of different glycoproteins with the aid of four different fucosyltransferases. The labeling processes were analyzed by in‐gel fluorescence and fluorescence polarization measurements. Comparison with the ATTO‐labeled sugar revealed that the FITC‐labeled fucose was the best of these substrates, and that the bacterial enzyme HP‐FucT tolerated the fluorescent substrates better than human fucosyltransferases.