Biochemical evidence for the role of alkyl-lysophospholipids on liver sialyltransferase

1. l. Antineoplastic alkyl-lysophospholipids were found to exert a strong inhibitory effect on membranous or solubilized asialomucin-sialyltransferase (CMP- N-acetylneuraminate: d-galactosyl-glycoprotein N-acetylneuraminyltransferase, EC 2.4.99.1) activity. 2. 2. This inhibitory effect was dependent on the presence of the choline moiety in position 3 of the glycerol molecule, as well as on the presence of long ether-linked aliphatic side chain in position 1 and the absence of any large substituent in position 2. 3. 3. As an example, 1-octadecyl-2- O-methyl-glycero-3-phosphorylcholine acted as a mixed-type inhibitor. 4. 4. Such an inhibitory process on sialyltransferase activity might be an additional factor in the tumor cell destructive effect of alkyl-lysophospholipids.