Legrand P

References (2)

Title : Effect of preduodenal lipase inhibition in suckling rats on dietary octanoic acid (C8:0) gastric absorption and plasma octanoylated ghrelin concentration - Lemarie_2016_Biochim.Biophys.Acta_1861_1111
Author(s) : Lemarie F , Cavalier JF , Garcia C , Boissel F , Point V , Catheline D , Legrand P , Carriere F , Rioux V
Ref : Biochimica & Biophysica Acta , 1861 :1111 , 2016
Abstract : Part of medium chain fatty acids (MCFAs) coming from dietary triglycerides (TGs) can be directly absorbed through the gastric mucosa after the action of preduodenal lipase (lingual lipase in the rat). MCFA gastric absorption, particularly that of octanoic acid (C8:0), may have a physiological importance in the octanoylation of ghrelin, the orexigenic gastric peptide acting as an endogenous ligand of the hypothalamic growth hormone secretagogue receptor 1a (GHSR-1a). However, the amount of C8:0 absorbed in the stomach and its metabolic fate still haven't been clearly characterized. The purpose of the present study was to further characterize and quantify the importance of preduodenal lipase activity on the release and gastric absorption of dietary C8:0 and on the subsequent ghrelin octanoylation in the stomach mucosa. Fifteen days old rats received fat emulsions containing triolein or [1,1,1-(13)C]-Tri-C8:0 and a specific inhibitor of preduodenal lipase, 5-(2-(benzyloxy)ethoxy)-3-(3-phenoxyphenyl)-1,3,4-oxadiazol-2(3H)-one or BemPPOX. The fate of the (13)C-C8:0 was followed in rat tissues after 30 and 120min of digestion and octanoylated ghrelin was measured in the plasma. This work (1) demonstrates that part of C8:0 coming from Tri-C8:0 is directly absorbed at the gastric level, (2) allows the estimation of C8:0 gastric absorption level (1.3% of the (13)C-C8:0 in sn-3 position after 30min of digestion), as well as (3) the contribution of rat lingual lipase to total lipolysis and to duodenal absorption of dietary FAs (at least 30%), (4) shows no short-term effect of dietary Tri-C8:0 consumption and subsequent increase of C8:0 gastric tissue content on plasma octanoylated ghrelin concentration.
ESTHER : Lemarie_2016_Biochim.Biophys.Acta_1861_1111
PubMedSearch : Lemarie_2016_Biochim.Biophys.Acta_1861_1111
PubMedID: 27317984

Title : Role of aspartate 70 and tryptophan 82 in binding of succinyldithiocholine to human butyrylcholinesterase - Masson_1997_Biochemistry_36_2266
Author(s) : Masson P , Legrand P , Bartels CF , Froment MT , Schopfer LM , Lockridge O
Ref : Biochemistry , 36 :2266 , 1997
Abstract : The atypical variant of human butyrylcholinesterase has Gly in place of Asp 70. Patients with this D70G mutation respond abnormally to the muscle relaxant succinyldicholine, experiencing hours of apnea rather than the intended 3 min. Asp 70 is at the rim of the active site gorge 12 A from the active site Ser 198. An unanswered question in the literature is why the atypical variant has a 10-fold increase in Km for compounds with a single positive charge but a 100-fold increase in Km for compounds with two positive charges. We mutated residues Asp 70, Trp 82, Trp 231, Glu 197, and Tyr 332 and expressed mutant enzymes in mammalian cells. Steady-state kinetic parameters for hydrolysis of butyrylthiocholine, benzoylcholine, succinyldithiocholine, and o-nitrophenyl butyrate were determined. The wild type and the D70G mutant had identical k(cat) values for all substrates. Molecular modeling and molecular dynamics suggested that succinyldicholine could bind in two consecutive orientations in the active site gorge; formation of one complex caused a conformational change in the omega loop involving Asp 70 and Trp 82. We propose the formation of three enzyme-substrate intermediates preceding the acyl-enzyme intermediate; kinetic data support this contention. Substrates with a single positive charge interact with Asp 70 just once, whereas substrates with two positive charges, for example succinyldithiocholine, interact with Asp 70 in two complexes, thus explaining the 10- and 100-fold increases in Km in the D70G mutant.
ESTHER : Masson_1997_Biochemistry_36_2266
PubMedSearch : Masson_1997_Biochemistry_36_2266
PubMedID: 9047329