Squalene-Hopene Cyclase: Mechanistic Insights into the Polycyclization Cascades of Squalene Analogs Bearing Ethyl and Hydroxymethyl Groups at the C-2 and C-23 Positions
作者:Ikki Kaneko、Yuri Terasawa、Tsutomu Hoshino
DOI:10.1002/chem.201801668
日期:2018.8.1
Squalene‐hopene cyclase (SHC) catalyzes the conversion of squalene 1 into 6,6,6,6,5‐fused pentacyclic hopene 2 and hopanol 3. To elucidate the binding sites for the terminal positions of 1, four analogs, having the larger ethyl (Et) and the hydrophilic CH2OH groups at the 23E or 23Z positions of 1, were incubated with SHC. The analog with the Et group at the 23E position (23E‐Et‐1) yielded two tetra‐ and three pentacyclic
Triterpenoid chlorin esters: Water column transformation products of chlorophyll a
作者:Paul J. Harradine、Torren M. Peakman、James R. Maxwell
DOI:10.1016/0040-4020(96)00800-9
日期:1996.10
The (22R)-30a,30b-dihomohopan-30b-yl and tetrahymanyl esters of pyrophaeophorbide a, chlorophyll a transformationproducts resulting from zooplankton herbivory, occur in an extract of surface sediment from Lake Valencia (Venezuela). The former was identified by HPLC-PDA-MS comparison with a standard and the latter after reduction of the extract and GC-MS analysis of the released alcohols.
From bio- to geohopanoids: an efficient abiotic passage promoted by oxygen in the presence of cuprous chloride
作者:Philippe Bisseret、Michel Rohmer
DOI:10.1016/0040-4039(95)01408-a
日期:1995.9
In the presence of cuprous chloride, the representative biohopanoid la was smoothly converted by oxidation in pyridine into aldehydes, ketones and carboxylic acids with the same skeletons as those of molecular fossils ubiquitously found in the organic matter of sediments.
Novel hopanoid derivatives released by oxidation of Messel shale kerogen
作者:Christine Reiss、Philippe Blanc、Jean M. Trendel、Pierre Albrecht
DOI:10.1016/s0040-4020(97)00261-5
日期:1997.4
Oxidation of Messel share kerogen using ruthenium tetroxide yielded several series of hopanoid triterpenes which have been identified by synthesis. These compounds could originate from hopenes or hopanes of bacterial origin linked to the kerogen; their structures indicate that incorporation processes into macromolecular entities of their biological precursors must occur at a rather early stage of diagenesis. (C) 1997 Elsevier Science Ltd.