Hydrolysis of a fluorescent substance formed from an oxidized phospholipid and an amino compound by phospholipase A2

Phosphatidylcholine hydroperoxide produced a fluorescent substance (FS-III) through reaction with 1-aminopentane after preincubation with heme methyl ester as a model system. The FS-III was retained at the 2-position of the glycerol backbone of phosphtidylcholine without breakdown into low molecular weight compounds. Phosphatidylcholine oxidized by catalysis with ferrous ion and ascorbic acid also produced the same fluorescent substance (FS-III). Phospholipase A₂ specifically hydrolyzed the FS-III attached to the phospholipid, making it possible to elute the same fluorescent substance (FS-II) as that obtained from oxidized methyl linoleate. The release of FS-II by hydrolysis of FS-III attached to phospholipid increased with greater phospholipase A₂ activity. It is suggested that, with aging, the accumulation of fluorescent lipofuscin pigments in biomembranes may be related to changes in the peroxidized phospholipid content and that phospholipase A₂ may play a role in decreasing the formation and accumulation of fluorescent phospholipids in biomembranes.