Identification of a calcium-independent phospholipase A2 in rat lung cytosol and differentiation from acetylhydrolase for 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine (PAF-acether).
The 100 000 X g supernatant of total rat lung homogenate was found to contain at least three phospholipase A2-type activities. Gel filtration separated a low molecular weight and Ca2+-requiring phospholipase A2 from Ca2+-independent acylhydrolase peak with an apparent higher molecular weight. Upon DEAE-cellulose chromatography this fraction was separated into a Ca2+-independent acylhydrolase and a Ca2+-independent platelet-activating factor-acetylhydrolase with no apparent overlap in acyl chain length specificity. The long-chain acylhydrolase was shown to exhibit specificity for the ester bond at the sn-2-position. Ca2+-independent phospholipase A2 activity was inhibited by p-bromophenacylbromide and was resistant to diisopropylfluorophosphate. In contrast, the Ca2+-independent acetylhydrolase activity was inhibited by diisopropylfluorophosphate but was unaffected by p-bromophenacylbromide.
J G
JG
Nijssen
C F
CF
Roosenboom
H
H
van den Bosch
D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D003600:Cytosol / Q000201:enzymology; D003840:Deoxycholic Acid / Q000494:pharmacology; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D005459:Fluorides / Q000494:pharmacology; D008168:Lung / Q000166:cytology / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D010972:Platelet Activating Factor / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000098:Acetophenones; D010972:Platelet Activating Factor; D003840:Deoxycholic Acid; D004228:Dithionitrobenzoic Acid; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D008274:Magnesium; C006821:4-bromophenacyl bromide; D005459:Fluorides; D002118:Calcium