The Study on Phosphatidylinositol-Specific Phospholipase C from Bacillus thuringiensis : Synthesis of Homogeneous Substrates, Substrate Specificity and Other Properties

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The properties of phosphatidylinositol-specific phospholipase C (PI-PLC) from Bacillus thuringiensis were studied in detail. The enzyme was extremely thermostable in 0.1% bovine serum albumin and retained 73% of its activity at 100℃ for 10 min, while it was labile in the absence of albumin. The enzymatic activity was inhibited by HgCl_2 or p-chloromercuriphenylsulfonic acid and restored by dithiothreitol. The kinetic parameters (k_m and V_<max>) of PI-PLC were determined for the mixed micelle of yeast phosphatidylinositol (PI)/Triton X-100 or sodium deoxycholate. Four PIs having different acyl chains : dilauroylphosphatidylinositol (DLPI), dimyristoylphosphatidylinositol (DMPI), dipalmitoylphosphatidylinositol (DPPI) and dioleoylphosphatidylinositol (DOPI) were synthesized from yeast PI through the processes of deacylation and reacylation, identified by infrared (IR) and Fourier transform nuclear magnetic resonance (FT-NMR) spectra, and subjected to the action of PI-PLC. All the syntheric PIs were hydrolyzed by this enzyme, with DLPI and DMPI being the best substrates. PI-PLC did not catalyze the hydrolysis of the phosphatidylnucleosides 5'-phosphatidylcytidine, 5'-phosphatidyluridine, 5'-phosphatidylthymidine, 5'-phosphatidyladenosine and 5'-phosphatidyl-2'-deoxyadenosine.
公益社団法人日本薬学会の論文
1992-08-25