The Hydrolysis of Phosphatidyl-Alcohols by Phospholipases A2: Effect of Head Group Size and Polarity

摘要: The ability of a variety secretory phospholipases A2 (sPLA2: EC 3.1.1.4) to bind and hydrolyse series phosphatidyl-alcohol substrates, in the absence detergent, was explored by both fluorescence-based kinetic interfacial binding assays. enzymes used were sPLA2 from porcine pancreas, Naja naja venom recombinant human non-pancreatic enzyme. Four dioleoyl phosphatidyl-alcohols with different headgroups, methanol, ethanol, propanol butanol. Comparative analyses phosphatidyl-choline, phosphatidyl-glycerol wheat germ phosphatidyl-inositol are also described. With series, as headgroup acyl-chain length increased susceptibility hydrolysis decreased. This effect much more pronounced than pancreatic Maximum activity this assay system observed phosphatidyl-methanol (1440 +/- 167 micromol/min/mg). We demonstrate that slow rate phosphatidyl-propanol enzyme (4.56 0.90 micromol/min/mg) is not due lack binding. mixtures phosphatidyl-choline various molar proportions suggests good mixing two phospholipids minimal phospholipid domain formation under these conditions. present strong evidence for stimulation presence little 1 mol% (<40 fold total enhancement). Overall, results rates anionic vary considerably close structurally related family. tight poorly hydrolysable vesicles provides novel mechanism inhibition sequestration.