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Characterization of phospholipase A 2 from rabbit lung microsomes
Author(s) -
Filgueiras Octávio M. O.,
Possmayer Fred
Publication year - 1987
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02533973
Subject(s) - lipidology , microsome , clinical chemistry , rabbit (cipher) , chemistry , chromatography , biochemistry , enzyme , computer science , computer security
A phospholipase A 2 activity associated with the microsomal fraction of rabbit lung homogenates was studied. The enzyme showed specificity for the sn −2 ester bond of phosphatidylcholine, had an alkaline pH optimum and required Ca 2+ for activity. Other divalent cations were unable to support hydrolysis. In the absence of detergents, exogenous phosphatidylethanolamine was deacylated at a rate sevenfold higher than phosphatidylcholine. The activity toward both substrates could be enhanced by sodium deoxycholate or, more effectively, by sodium taurodeoxycholate. Phosphatidylethanolamine required higher detergent/phospholipid molar ratios than phosphatidylcholine. Under these conditions, the preference for the former substrate over the latter was nearly abolished. The zwitterionic detergent 3‐[(3‐cholamidopropyl) dimethylammonio]‐1‐propanesulfonate (CHAPS) and the nonionic detergent Triton X‐100 were either ineffective (phosphatidylcholine) or inhibitory (phosphatidylethanolamine). Addition of KCl produced opposite effects on the activity depending on the bile salt used to disperse the substrate. The phospholipase A 2 activity was inhibited by p ‐bromophenacyl bromide but remained unaffected after treatment with diisopropylfluorophosphate or NaF. N‐Ethylmaleimide, but not other thiol reagents, partially inhibited the activity.