Enantioselective Total Synthesis of the Archaeal Lipid Parallel GDGT-0

Archaeal glycerol dibiphytanyl glycerol tetraethers (GDGT) are some of the most unusual membrane lipids identified in nature. These amphiphiles are the major constituents of the membranes of numerous <i>Archaea</i>, some of which are extremophilic organisms. Due to their unique structures, there has been significant interest in studying both the biophysical properties and the biosynthesis of these molecules. However, these studies have thus far been hampered by limited access to chemically pure samples. Herein, we report a concise and stereoselective synthesis of the archaeal tetraether lipid GDGT-0 and the synthesis and self-assembly of derivatives bearing different polar groups.

Enantioselective Total Synthesis of the Archaeal Lipid Parallel GDGT-0

Archaeal glycerol dibiphytanyl glycerol tetraethers (GDGT) are some of the most unusual membrane lipids identified in nature. These amphiphiles are the major constituents of the membranes of numerous <i>Archaea</i>, some of which are extremophilic organisms. Due to their unique structures, there has been significant interest in studying both the biophysical properties and the biosynthesis of these molecules. However, these studies have thus far been hampered by limited access to chemically pure samples. Herein, we report a concise and stereoselective synthesis of the archaeal tetraether lipid GDGT-0 and the synthesis and self-assembly of derivatives bearing different polar groups.

Enantioselective Total Synthesis of the Archaeal Lipid Parallel GDGT-0

Archaeal glycerol dibiphytanyl glycerol tetraethers (GDGT) are some of the most unusual membrane lipids identified in nature. These amphiphiles are the major constituents of the membranes of numerous <i>Archaea</i>, some of which are extremophilic organisms. Due to their unique structures, there has been significant interest in studying both the biophysical properties and the biosynthesis of these molecules. However, these studies have thus far been hampered by limited access to chemically pure samples. Herein, we report a concise and stereoselective synthesis of the archaeal tetraether lipid GDGT-0 and the synthesis and self-assembly of derivatives bearing different polar groups.

Total Synthesis of the Alleged Structure of Crenarchaeol Enables Structure Revision

This study describes the first asymmetric total synthesis of the proposed structure of the archaeal membrane-spanning tetraether lipid crenarchaeol. The synthetic material was compared by NMR and GC-MS analysis with natural crenarchaeol. Detailed NMR analysis ultimately enabled the structure revision of crenarchaeol, identifying one out of 22 sterecenters to be inverted.

Total Synthesis of the Alleged Structure of Crenarchaeol Enables Structure Revision

This study describes the first asymmetric total synthesis of the proposed structure of the archaeal membrane-spanning tetraether lipid crenarchaeol. The synthetic material was compared by NMR and GC-MS analysis with natural crenarchaeol. Detailed NMR analysis ultimately enabled the structure revision of crenarchaeol, identifying one out of 22 sterecenters to be inverted.

Evolution of upper water column structure inferred from paired alkenone and tetraether lipid proxies in the central Japan/East Sea since 25 ka BP

&lt;p&gt;We measure and analyse the alkenone and tetraether lipid records over the past 25 ka, from a sediment core recovered from the central Japan/East Sea. In our results, U&lt;sup&gt;K&amp;#8242;&lt;/sup&gt;&lt;sub&gt;37&lt;/sub&gt;- and TEX&lt;sub&gt;86&lt;/sub&gt;- derived temperatures commonly represent warm signals during the period of 25-16.2 ka BP, indicating fresher and thus a stratified surface ocean. In comparison, the U&lt;sup&gt;K&amp;#8242;&lt;/sup&gt;&lt;sub&gt;37&lt;/sub&gt;- and TEX&lt;sub&gt;86&lt;/sub&gt;- derived temperatures become diverged abruptly after 16.2 ka BP, suggesting a thermal gradient between surface and subsurface water. In addition, the isoprenoidal glycerol dialkyl glycerol tetraethers (GDGT) community structure index, GDGT-[2]/[3] ratio is high during the period of 25-16.2 ka BP and drops sharply along with the TEX&lt;sub&gt;86&lt;/sub&gt;- derived temperatures at 16.2 ka BP, which is likely attributed to changes in the depth of GDGT export and/or in archaeal community structure. Specifically, the high GDGT-[2]/[3] ratio (larger than 8) can be related to strongly stratified surface Japan/East Sea. Moreover, the U&lt;sup&gt;K&amp;#8242;&lt;/sup&gt;&lt;sub&gt;37&lt;/sub&gt;- and TEX&lt;sub&gt;86&lt;/sub&gt;- derived temperatures start converging at 5.8 ka BP, representing the impact of the Tsushima Warm Current until nowadays. Note: This study was supported by the National Natural Science Foundation of China (Grants No. 41420104005, U1606401) and National Program on Global Change and Air-Sea Interaction (GASI-GEOGE-03 &amp;-04).&lt;/p&gt;