Kanda P, Wells MA. D-dihexanoylphosphatidylcholine is not a pure competitive inhibitor of phospholipase A2 hydrolysis of L-dihexanoylphosphatidylcholine.
Chem Phys Lipids 1985;
37:251-6. [PMID:
4042254 DOI:
10.1016/0009-3084(85)90013-1]
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Abstract
The inhibition of Crotalus adamanteus phospholipase A2 hydrolysis of L-dihexanoylphosphatidylcholine by D-dihexanoylphosphatidylcholine was investigated with inhibitor and substrate in the monomeric concentration range. The results showed that the D-enantiomer acts as a partial (not pure) competitive inhibitor of the enzyme. These results suggest that an ESI complex exists, in which hydrolysis of the substrate still occurs. Thus, binding of the D-enantiomer to the enzyme decreases the affinity for the substrate by a factor, alpha, while Vmax is unaffected. The value of alpha was determined to be 4.70 +/- 0.14. These findings complicate the use of D-phosphatidylcholines in mixed micelles with the L-enantiomer as a possible method to investigate the mechanism of interfacial activation of this enzyme.
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