Bis-(O)-acetylated derivative of 4,5-dihydroxy-2,3-pentanedione (DPD): a convenient stable precursor of quorum sensing autoinducer AI-2

International audienc

Synthetic homoserine lactone-derived sulfonylureas as inhibitors of Vibrio fischeri quorum sensing regulator

International audienceA series of 9 homoserine lactone-derived sulfonylureas substituted by an alkyl chain, some of them bearing a phenyl group at the extremity, have been prepared. All compounds were found to inhibit the action of 3-oxo-hexanoyl-l-homoserine lactone, the natural inducer of bioluminescence in the bacterium Vibrio fischeri, the aliphatic compounds being more active than their phenyl-substituted counterparts. Molecular modelling studies performed on the most active compound in each series suggest that the antagonist activity could be related to the perturbation of the hydrogen-bond network in the ligand–protein complexes

A continuous spectrophotometric assay that distinguishes between phospholipase A1 and A2 activities

International audienceA new spectrophotometric assay was developed to measure, continuously and specifically, phospholipase A1 (PLA1) or phospholipase A2 (PLA2) activities using synthetic glycerophosphatidylcholines (PCs) containing α-eleostearic acid, either at the sn-1 position [1-α-eleostearoyl-2-octadecyl-rac-glycero-3-phosphocholine (EOPC)] or at the sn-2 position [1-octadecyl-2-α-eleostearoyl-rac-glycero-3-phosphocholine (OEPC)]. The substrates were coated onto the wells of microtiter plates. A nonhydrolyzable ether bond, with a non-UV-absorbing alkyl chain, was introduced at the other sn position to prevent acyl chain migration during lipolysis. Upon enzyme action, α-eleostearic acid is liberated and then solubilized into the micellar phase. The PLA1 or PLA2 activity was measured by the increase in absorbance at 272 nm due to the transition of α-eleostearic acid from the adsorbed to the soluble state. EOPC and OEPC differentiate, with excellent accuracy, between PLA1 and PLA2 activity. Lecitase(®), guinea pig pancreatic lipase-related protein 2 (known to be a PLA1 enzyme), bee venom PLA2, and porcine pancreatic PLA2 were all used to validate the assay. Compared with current assays used for continuously measuring PLA1 or PLA2 activities and/or their inhibitors, the development of this sensitive enzymatic method, using coated PC substrate analogs to natural lipids and based on the UV spectroscopic properties of α-eleostearic acid, is a significant improvement

Synthesis of Phospholipids under Plausible Prebiotic Conditions and Analogies with Phospholipid Biochemistry for Origin of Life Studies

Phospholipids are essential components of biological membranes and are involved in cell signalization, in several enzymatic reactions, and in energy metabolism. In addition, phospholipids represent an evolutionary and non-negligible step in life emergence. Progress in the past decades has led to a deeper understanding of these unique hydrophobic molecules and their most pertinent functions in cell biology. Today, a growing interest in "prebiotic lipidomics"calls for a new assessment of these relevant biomolecules