Synthesis of acylthioester phospholipids and their hydrolysis by phospholipase A2

✍ Scribed by A.J. Aarsman; C.F.P. Roosenboom; G.A. van der Marel; B. Shadid; J.H. van Boom; H. van den Bosch

• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 775 KB
• Volume: 36
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(85)90004-0

✦ Synopsis

This paper describes the synthesis of short-chain phospholipid analogs with an acylthioester bond exclusively at the sn-2-position for use in spectrophotometric assays of phosphoripase A 2 in the presence of thiokeagents. 1-O-Octyl-2-deoxy-2-S-hexanoyl-sn-glycero-3-phosphocholine (thioC6PC), l-O-octyl-2-deoxy-2-S-heptanoyl-sn-glycero-3-phosphocholine (thio-C7PC), l-O-octyl-2-deoxy-2-S-hexanoyl-sn-glycerc~3-sulfate (thioC6 sulfate) and l-O-hexadecyl-2-deoxy-2-S-acetyl-sn-glycero-3-phosphocholine (thioacetyl PAF) were prepared by total synthesis starting from 1,2-isopropylidene-sn-glycerol. The thioester bond in these substrates was introduced by a Walden-inversion by reacting l-O-(4'-methoxytrityl)-3-O-octyi-2-tosyl-snglycerol with potassium thioacetate. Complete hydrolysis of the substrates by the stereospecific phospholipase A 2 from porcine pancreas confirmed the expected stereochemie, gl configuration. Although space Idling models of thioC7pc showed a great resemblance with those of 1,2-dioctanoyl-sn-glycero-3-phosphocholine (diC8PC) the hydrolysis rate for the thioester substrate was lower by at least two orders of magnitude. Studies with mixed micelles of these two substrates suggest that the reduced hydrolysis rate of thioester is more likely caused by subtle changes in the architecture of the substrate molecules per se than by a decreased quality of the interface.