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Updated: Aug 16, 2026

Single-molecule Super-resolution Imaging of Phosphatidylinositol 4,5-bisphosphate in the Plasma Membrane with Novel Fluorescent Probes
Published on: October 15, 2016
1-Palmitoyl-2-thiopalmitoyl phosphatidylcholine, a highly specific chromogenic substrate of phospholipase A2
C Balet1, K A Clingman, J Hajdu
1Department of Chemistry, California State University, Northridge 91330.
Abstract:
1-Palmitoyl-2-thiopalmitoyl phosphatidylcholine (2-thioPC), a structurally modified phospholipid analog is specifically hydrolyzed by phospholipase A2 to liberate 2-thiolysophosphatidylcholine and palmitic acid. The sulfhydryl group of the product is readily trapped by 5,5'-dithiobis (2-nitrobenzoic acid) allowing continuous spectrophotometric monitoring of the enzymatic reaction. The rates of hydrolysis by bee-venom phospholipase A2 have been determined in a series of Triton X-100 containing mixed micelles. At 1 mM 2-thioPC increasing the concentration of Triton X-100 from 4 to 16 mM changes the specific activity of bee-venom phospholipase A2 from 96.9 to 17.9 mumol/min/mg, about one order of magnitude lower than dipalmitoyl phosphatidylcholine hydrolysis in micelles of similar composition. The chromogenic substrate is the first phospholipid analog exhibiting absolute specificity for phospholipase A2 and should be applicable to spectrophotometric detection and kinetic characterization of both water soluble and membrane-bound forms.
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