title: Synthesis of sn-1 functionalized phospholipids as substrates for secretory phospholipase A2.
abstract: Secretory phospholipase A2 (sPLA2) represents a family of small water-soluble enzymes that catalyze the hydrolysis of phospholipids in the sn-2 position liberating free fatty acids and lysophospholipids. Herein we report the synthesis of two new phospholipids (1 and 2) with bulky allyl-substituents attached to the sn-1 position of the glycerol backbone. The synthesis of phospholipids 1 and 2 is based upon the construction of a key aldehyde intermediate 3 which locks the stereochemistry in the sn-2 position of the final phospholipids. The aldehyde functionality serves as the site for insertion of the allyl-substituents by a zinc mediated allylation. Small unilamellar liposomes composed of phospholipids 1 and 2 were subjected to sPLA2 activity measurements. Our results show that only phospholipid 1 is hydrolyzed by the enzyme. Molecular dynamics simulations revealed that the lack of hydrolysis of phospholipid 2 is due to steric hindrance caused by the bulky side chain of the substrate allowing only limited access of water molecules to the active site.
authors.affiliation: Department of Chemistry, Technical University of Denmark, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Linderoth
authors.forename: Günther H
authors.initials: GH
authors.lastname: Peters
authors.forename: Kent
authors.initials: K
authors.lastname: Jørgensen
authors.forename: Robert
authors.initials: R
authors.lastname: Madsen
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Andresen
mesh_terms: D000447:Aldehydes / Q000737:chemistry; D005994:Glycerophosphates / Q000138:chemical synthesis / Q000737:chemistry*; D054501:Group II Phospholipases A2; D006868:Hydrolysis; D010741:Phospholipases A / Q000737:chemistry*; D054467:Phospholipases A2; D011487:Protein Conformation; D013228:Stearates / Q000138:chemical synthesis / Q000737:chemistry*; D013379:Substrate Specificity
chemical_list: C520733:2,3-dihydroxypropyl 2'-octadecanoyloxy-3'-hexadecyloxy-4',4'-dimethylhex-5'-enyl phosphate; C520732:2,3-dihydroxypropyl 2'-octadecanoyloxy-3'-hexadecyloxyhex-5'-enyl phosphate; D000447:Aldehydes; D005994:Glycerophosphates; D013228:Stearates; D010741:Phospholipases A; D054501:Group II Phospholipases A2; D054467:Phospholipases A2