The nature of the phospholipases A of lung lamellar bodies.
Phospholipases A1 and A2 from rabbit lung lysosomes have maximal activity at pH 4.0 (Fig. 1). Lamellar bodies from rabbit lung contain phospholipases A which resemble the lysosomal enzymes in being active at pH 4 and showing sensitivity to inhibition by calcium ions (80% inhibition at 10 mM Ca2+). Lamellar body phospholipases hydrolyse dipalmitoyl phosphatidylcholine (containing 10% phosphatidylglycerol and thus approximating the phospholipid composition of mature lamellar bodies) at only 1% of their rate of hydrolysis of unsaturated molecules (Tables 1 and 2). This substrate preference corresponds to that shown by phospholipases from lysosomes.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008168:Lung / Q000201:enzymology* / Q000648:ultrastructure; D009940:Organoids / Q000201:enzymology; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D011817:Rabbits
D010740:Phospholipases; D010741:Phospholipases A; D002118:Calcium