Interfacial catalysis by phospholipases at conjugated lipid vesicles: colorimetric detection and NMR spectroscopy.
BACKGROUND
Self-assembled conjugated polymers are rapidly finding biological and biotechnological applications. This work describes a synthetic membrane system based on self-assembled polydiacetylenes, which are responsive to the enzymatic activity of phospholipases - a ubiquitous class of enzymes that catalyze the hydrolysis of phospholipid molecules embedded in cell membranes.


RESULTS
We show that phospholipases are active at bilayer vesicles composed of the natural enzyme substrate, dimyristoylphosphatidylcholine (DMPC), and a synthetic pi-conjugated polymerized lipid based on polydiacetylene (PDA). In addition, the enzymatic reaction induces an optical transition in the surrounding PDA matrix, visible to the naked eye. Nuclear magnetic resonance spectroscopy confirms the occurrence of enzymatic catalysis and reveals the fate of the cleavage products.


CONCLUSIONS
The results indicate that the structural and color changes of the PDA matrix are directly related to interfacial catalysis by phospholipase. This novel biocatalytic method of inducing optical transitions in conjugated polymers might lead to new approaches towards rapidly screening new enzyme inhibitor compounds.
Jelinek
R
R
Department of Chemistry Ben Gurion University of the Negev Beer-Sheva 84105 Israel.
Okada
S
S
Norvez
S
S
Charych
D
D
D000114:Acetylene / Q000031:analogs & derivatives; D002384:Catalysis; D003124:Colorimetry; D007202:Indicators and Reagents; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes; D009682:Magnetic Resonance Spectroscopy; D008567:Membranes, Artificial; D008855:Microscopy, Electron, Scanning; D010740:Phospholipases / Q000737:chemistry*; D000078789:Polyacetylene Polymer; D011108:Polymers; D053279:Polyynes; D013056:Spectrophotometry, Ultraviolet
D007202:Indicators and Reagents; D008055:Lipids; D008081:Liposomes; D008567:Membranes, Artificial; D000078789:Polyacetylene Polymer; D011108:Polymers; D053279:Polyynes; C082361:polydiacetylene; D010740:Phospholipases; D000114:Acetylene