Novel reversible, irreversible and fluorescent inhibitors of platelet-activating factor acetylhydrolase as mechanistic probes

• Verfasst von: Deigner, Hans-Peter [VerfasserIn]
• Verfasst von: Kinscherf, Ralf [VerfasserIn]
• Verfasst von: Claus, Ralf [VerfasserIn]
• Verfasst von: Fyrnys, Beatrix [VerfasserIn]
• Verfasst von: Blencowe, Christopher [VerfasserIn]
• Titel: Novel reversible, irreversible and fluorescent inhibitors of platelet-activating factor acetylhydrolase as mechanistic probes
• Verf.angabe: Hans P. Deigner, Ralf Kinscherf, Ralf Claus, Beatrix Fyrnys, Christopher Blencowe, A. Hermetter
• Umfang: 12 S.
• Fussnoten: Gesehen am 14.09.2017
• Titel Quelle: Enthalten in: Atherosclerosis
• Jahr Quelle: 1999
• Band/Heft Quelle: 144(1999), 1, S. 79-90
• ISSN Quelle: 1879-1484
• DOI: doi:10.1016/S0021-9150(99)00034-9
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1563497239

Abstract

Phosphatidylcholines (1-O-alcoxy-2-amino-2-desoxy-phosphocholines and 1-pyrene-labeled analogs) were synthesized and used to examine interactions with recombinant human PAF-acetylhydrolase (PAF-AH), an enzyme purified from plasma, and with macrophage-like U937 cells. Novel phosphatidylcholines containing a sn-2-carbamoylester group such as 1-O-hexadecyl-2-desoxy-2-amino-methylcarbamoyl-2-methyl-rac-glycero-3-phosphocholine 11 were found to act as site-specific irreversible enzyme inhibitors with Ki-values up to 83 (Kirev) and 177 (Ki(inact)) μm. The compounds exhibit only marginal inhibition of Ca2+-dependent phospholipases. Kinetic data show that phosphocholines carrying a terminal sn-1-pyrene moiety inhibit PAF-AH activity with an effectivity similar to analogs with an aliphatic chain. 1-O-Decyloxy-[10-(4-pyrenyl)-butoxy]-2-desoxy-2-amino-carbamoyl-methyl-rac-glycero-3-phosphocholine 13 could be used for enzyme labeling and to demonstrate an inhibitor-enzyme stoichiometry of 0.7:1. At 8°C, the compound accumulated in the membranes of U937 cells, at 37°C it was internalized into intracellular compartments. Structure-activity studies in a mixed micelle assay indicated that the inhibition power of reversible and irreversible inhibitors increases along with the (sn)-1-chain length similar to the structure-dependent binding of ether phospholipids to the PAF-receptor. Unlike the situation at the (sn)-1-position, increasing chain length at the sn-2-position, or an alkyl branching of the glycerol backbone significantly reduced the inhibitory potency.