Conversion of glycosylphosphatidylinositol (GPI)-anchored alkaline phosphatase by GPI-PLD.
Enzymatic conversion of brain glycosylphosphatidylinositol-linked alkaline phosphatase (GPI-AP), amphiphilic, was examined. When GPI-AP was incubated with glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD), a negligible conversion of GPI-AP to hydrophilic form was observed. The inclusion of monoacylglycerols enhanced the enzymatic conversion, although the action of monoacylglycerols differed greatly according to the size of acyl group; the enzymatic conversion was enhanced considerably in the presence of monoacylglycerols possessing acyl group of longer chain length (C10-C18), while monoacylglycerols with acyl moiety of shorter length (C4-C8) did fail to augment the enzymatic conversion. Noteworthy, monooleoylglycerol was much more effective than the other monoacylglycerols in promoting the enzymatic conversion, indicating a beneficial role of the unsaturation in acyl chain. Meanwhile, ionic amphiphiles such as monohexadecyllysophosphatidylcholine and palmitoyl-carnitine decreased the enzymatic conversion of GPI-AP in a concentration-dependent manner, with monohexadecyllysophosphatidylcholine being more inhibitory than palmitoylcarnitine. Separately, when GPI-AP was exposed to various oxidants prior to the incubation with GPI-PLD, a remarkable decrease of the enzymatic conversion was observed with hypochlorite and peroxynitrite generators, but not H2O2. In further study, hypochlorite was found to inactivate GPI-PLD at low concentrations (3 to approximately 100 microM). From these results, it is suggested that the enzymatic conversion of GPI-AP by GPI-PLD may be regulated in vivo system.
College of Pharmacy, Chungnam National University, Taejon, Korea.
Y G
YG
Moon
H J
HJ
Lee
M R
MR
Kim
P K
PK
Myung
S Y
SY
Park
D E
DE
Sok
D015720:5'-Nucleotidase / Q000378:metabolism*; D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005989:Glycerides / Q000737:chemistry / Q000494:pharmacology; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D066298:In Vitro Techniques; D016877:Oxidants / Q000494:pharmacology; D010739:Phospholipase D / Q000494:pharmacology*
D005989:Glycerides; D017261:Glycosylphosphatidylinositols; D016877:Oxidants; D000469:Alkaline Phosphatase; D015720:5'-Nucleotidase; D010739:Phospholipase D; C065017:glycoprotein phospholipase D