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Inhibition of the Clostridium perfringens phospholipase C hydrolysis of a thiophosphate analog of lysophosphatidylcholine by micelle‐bound ammonium and sulfonium cations
Author(s) -
Young Paul R.,
Snyder William R.,
McMahon Rosemary F.
Publication year - 1991
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/bf02535984
Subject(s) - chemistry , bromide , micelle , lysophosphatidylcholine , hydrolysis , medicinal chemistry , mole fraction , organic chemistry , stereochemistry , phosphatidylcholine , phospholipid , biochemistry , membrane , aqueous solution
Cetyltrimethylammonium and n ‐octadecyldimethylsulfonium bromides inhibit the Clostridium perfringens phospholipase C‐catalyzed hydrolysis of 1‐ S ‐phosphocholine‐2‐ O ‐hexadecanoyl‐1‐mercapto‐2‐ethanol (1) at pH 7.5, 37°C, μ=0.15 with KCl. Mixed micelles containing 1 and either inhibitor are substrates for the enzyme and the fraction of activity remaining is a monotonic, but nonlinear function of the mole fraction of inhibitor. Simple saturation kinetics are observed as the concentration of 1 is increased in mixed micelles containing a constant mole fraction of inhibitor. Inhibition constants for cetyltrimethylammonium and n ‐octadecyldimethylsulfonium bromides are 0.66±0.04 and 0.25±0.02 mM, respectively. The data suggest that the significant inhibition previously observed for soluble alkyldisulfonium salts ( K 50 for dodecamethylene‐ bis (dimethylsulfonium) bromide, 27μM) is dependent upon bifunctional cationic interactions rather than hydrophobic binding.