Effects of hypochlorous acid on unsaturated phosphatidylcholines

Effects of hypochlorous acid and of the myeloperoxidase-hydrogen peroxide-c hloride system on mono- and polyunsaturated phosphatidylcholines were analy zed by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), Chlorohydrins and glycols were detected a s main products according to the characteristic shift of molecular masses. Mainly mono-chlorohydrins result upon the incubation of HOCl/-OCl with 1-pa lmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, whereas only traces of mono-g lycols were detected. 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine yiel ded a complex mixture of products. Mono-chlorohydrins and glycols dominated only at short incubation, while bis-chlorohydrins as well as products cont aining one chlorohydrin and one glycol moiety appeared after longer incubat ion. Similarly, a complex product mixture resulted upon incubation of 1-ste aroyl-2-arachidonoyl-sn-glycero-3-phosphocholine with hypochlorous acid. Ad ditionally, tris-chlorohydrins, products with two chlorohydrin and one glyc ol moiety, as well as lysophosphatidylcholines and fragmentation products o f the arachidonoyl side chain were detectable. Mono-chlorohydrins of 1-stea royl-2-oleoyl-sn-glycero-3-phosphocholine were detected after the incubatio n of the latter phospholipid with the myeloperoxidase-hydrogen peroxide-chl oride system at pH 6.0. These chlorohydrins were not observed in the absenc e of chloride, hydrogen peroxide, or myeloperoxidase as well as in the pres ence of methionine, taurine, or sodium azide. Thus, mono-chlorohydrins in 1 -stearoyl-2-oleoyi-sn-glycero-3-phosphocholine produced by hypochlorous aci d from the myeloperoxidase-hydrogen peroxide-chloride system can also be de tected by means of MALDI-TOF MS. (C) 2001 Elsevier Science Inc.